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adatesman
climber
philadelphia, pa
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Topic Author's Original Post - Jan 31, 2013 - 03:55pm PT
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Howdy Folks!
I've been quiet in the What You're building thread because the 1850's schoolhouse renovation hit a snag, which lead to a long story involving buying a 1950's Case 310 Loader/Backhoe.
Lots to catch up on the details, but right now anyone know much about spool valves? This spool is from the (currently non-functioning) power steering, and I'm unsure if the pitting at the end will cause me problems. Replacement is not an option (part was specific to this model, which is long since our of stock). Turning and sleeping is an option, but I don't have a toolpost grinder for the lathe so have concerns about surface finish for the o-ring seal...
If it makes a difference, the spool valve is bolted to the end of the steering cylinder, which runs the width of the front axle (as opposed to the rotary type on the steering column). I tried an old tractor forum with no success, so tossing the question here in hopes the wide scope of experience turns up a solution.
Oh, and I'be basically rebuilt the pump at this point, complete with remachining the bore for the gerotor. What a PITA that was...
Thx, and hopefully someone chimes in with an answer quick... I've got a weather window to get this assembled and working, at which point I have to put in 250 feet of French drain 5 feet deep. All to get the indoor plaster repairs to stop popping off...
-Aric.
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Juan Maderita
Trad climber
"OBcean" San Diego, CA
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Jan 31, 2013 - 05:03pm PT
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Disclaimer: I don't know anything about the specific part.
I'd take it to a competent machine shop. The surface is round and steel. So it should be no problem to weld new material and turn it down to specs on a lathe. Good as new for a few dollars.
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pud
climber
Sportbikeville & Yucca brevifolia
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Jan 31, 2013 - 05:05pm PT
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Can you replace the steering box (pump) with another?
Not enough info in your post to know whether or not this is feasible.
If so, they can be had cheap at most used farm equipment yards.
You can also check some of the bigger manufacturers to see if they can tool it for you. Machine tolerances in the 50's were quite different than today. You may be able to have a local machine shop turn it for you.
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hillrat
Trad climber
reno, nv
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Jan 31, 2013 - 05:17pm PT
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If an o-ring rides on that surface you will definitely develop a leak there. Generally the outer passages of a spool valve are on the low pressure return side, but that can still run a couple hundred psi, so the leak could be significant. If its not a very hard assembly/disaspembly process you might smooth it down some and try it to see just how bad it is.
Otherwise, its probably better to turn it down and sleeve it as opposed to welding and turning. Spool valves are often very close tolerances and any warpage from welding heat will be likely to make it stick in the bore.
Good luck!
Oh yeah, don,t ever try to find a hydraulic leak with your hands- risks oil injection. And dont trust yer life to a load suspended by a hydraulic system.
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Jan 31, 2013 - 10:37pm PT
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Was wondering if this would get a response, and not only thanks for the input, but thanks for input from folks this long-time-lurker has never heard of.
Juan- welding not an option, as it'll warp the spool and I have no way to grind it back to concentric.
Pud- It's an Eaton pump, which they last made ~1960. Neither replacements nor parts are available. And flipping through Grainger and McMaster for a 1200psi 6gpm pump I'm looking at $400, so given I paid $2600 for the whole shebang that's not really an option (especially since I'll be selling it when I'm done with this project).
Hillrat- best advice I've yet seen on ST. pressure + oil = bad juju. Learned that long ago. Not knowing whether the problem is the pump, the linkage, the spool valve or the cylinder I've gone ahead and replaced all the seals and bolted everything back together.
Naturally the factory seal kit included an o-ring I didn't need, and the parts diagram detailed a relief valve that isn't physically there...
Ah, the joys of old machinery......
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FRUMY
Trad climber
SHERMAN OAKS,CA
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Jan 31, 2013 - 10:43pm PT
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Why not sleeve it? If you have a lathe cut it past the pitting & turn a sleeve then press the sleeve on .
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TGT
Social climber
So Cal
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Jan 31, 2013 - 10:46pm PT
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Have it hard chrome plated up past size then ground back down and and polished.
good as new!
shrinking a sleeve on it might not be a bad option either.
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hillrat
Trad climber
reno, nv
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Jan 31, 2013 - 11:34pm PT
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Guessing you don't have a schematic? I'm fair at hydraulic diagnosis when I've got the machine in front of me...
Non-functioning power steering makes for a long day in the field. If I knew how the thing was built (the schematic, naturally) I might point you in a direction to check.
So the valve is bolted to the end of the steering cylinder? How is it actuated and what does it do? It's a pretty short spool, and just from looking at it I assumed the pitted area is exposed to the elements. Too much to guess about being unfamiliar with that particular tractor. Newer ones have priority valves and such; but that's not necessarily what you've got.
One thing you can do is eliminate the steering cylinder itself by checking for internal leakage:
1. bottom out the cylinder in either direction
2. figure out which end should have the pressure going to it if you were to try to bottom it out further
3. remove the hose to the NON pressure side and cap off the hose, leaving the cylinder open
4. continue to try bottoming out the cylinder. No oil should pass through and come out the open cylinder port. If it does, the piston seals are leaking. Assuming the valve does not directly feed into the cylinder, which would complicate things.
It's a pretty easy test if you're good with hydraulics. If you're not, it can make a mess in a hurry. And of course you run risks opening the system and pressurizing things with an open line. That's really the abbreviated version. Remember things can move unexpectedly when you open a system, fluid under pressure is dangerous, don't get crushed, etc. Hell, probably best to get a textbook that covers the test in detail instead of trying to follow my advice.
Also would be a great idea to T in a gauge somewhere in the steering system and see if you've got pressure.
But, ya know... Heavy equipment is dangerous. Like climbing.
Yer gonna die!
Is it just the steering that doesn't work? The rest ok? Brakes, loader, backhoe?
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 1, 2013 - 01:09am PT
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TGT- repair along what you describe will cost more than I paid for the whole thing, so that's out.
Hillrat- You're exactly who I was hoping to smoke out... :-)
Only thing I have is a really bad parts diagram, which is a Java applet, so won't even bother to link. The "rebuild kit" I received today totaled 5 o-rings, but there's at least a dozen used in that general area. In hindsight, I now see all but 5 had part numbers, but they could at least have told me while I was on the phone with them.
Anyway, where I'm at is that I'm not sure the pump is even making pressure. After fiddling with it there is max .006" clearance between the ring and rotor (gerotor pump). Not much pitting/wear on either, and I machined the depth of the bore to allow .001" clearance. Lathe was a Clausing 5917 and I grew up working in a machine shop, and dear lord was that setup a PITA.... I really need a proper sized 4 jaw chuck, as that would have cut the setup time in half.
What I've done is "as it was", many, many iterations of left/right/left/right/left/right/why is the reservoir full of foam?, at which point I switched from "tranny fluid" (per the manual) to power steering fluid (supposedly less foamy, and seems to be the case).
Going by your numbering, 2: matched the pressure line per the parts diagram. Done that, not sure it's right given there's a mistake or two in the parts diagram. FWIW, Case has been bought out a half dozen times, and getting parts diagrams for the old equipment is not high on the priority list.
3. if I'm reading right, it's an open headed spool, and I'm getting oodles of flow even with the spool centered. Lots of foam though, and I'll be (once again) tearing the rexervoir apart tomorrow (today?) and replacing all of the gaskets I can find. The pump is getting air somewhere, and be damned if I can figure out where...
4.This is complicated by not knowing if the pump is any good. Will know later today (meaning Friday, at this point), so likely when you're coffee is cooled down enough to drink.
Thanks Hillrat, this is *exactly* the type of help I'm needing,
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 1, 2013 - 01:20am PT
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Also would be a great idea to T in a gauge somewhere in the steering system and see if you've got pressure.
But, ya know... Heavy equipment is dangerous. Like climbing.
Yer gonna die!
Is it just the steering that doesn't work? The rest ok? Brakes, loader, backhoe?
Done that, no pressure. Pulled the pump apart, cleaned and reassembled, got it up to 400psi when the 4L belt slipped. Should hit 1200psi deadheaded/relief opens, but poorly-executed 12V Positive Alternator conversion is not helping things.
Yup, gonna die... eventually. :-)
Loader works just fine, although a bit out of level. Picks up the front just fine. Stabilizers in back pick up the back just fine. Backhoe tries but fails to pick up the back. Found and checked the dipstick, an oil was barely touching it. Added a quart, no change. Another quart, no change. A third, no change. Then went to Google and found it's a 17 gallon tank. Never in my life thought I'd buy a 5 gallon bucket of oil to top something off. But that's next week's problem, as right now no power steering + 1000 pounds in the front bucket = I hit things I shouldn't be anywhere near. :-(
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 1, 2013 - 01:27am PT
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BTW Hillrat, if any of this makes sense and you don't mind, kindly drop me a PM with your phone number and a convenient time to call. I'll likely be tapping maple trees in the AM, but should be over working on the backhoe by the time you (presumably) west coasters are up and about. :-)
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FRUMY
Trad climber
SHERMAN OAKS,CA
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Sleeving it would be easy & not take long at all.
I've sleeved hundreds of input shafts & output shafts & thousands of clutch drums for automatic transmission. It would take no more than two hours to chuck up your shaft cut it down & cut a small piece of 4130 chrome molly to press over the end.
I'm sorry I'm on the road or I'd do it for nothing for you.
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 2, 2013 - 12:34pm PT
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Hey Folks,
Thanks again for the help. I think I'm finally on the road to getting this thing working....
Yesterday was spent installing and testing the pump, and looks like that's working ok. Not great, as it will only hit 800psi before the crank pulley slips, but not too bad since the relief is set to 1000psi or so. I suppose I could do something about the slippage, but the setup is more than a bit hokey... The belt on the crank turns the alternator and water pump, and a double groove pulley on the alt turns the power steering pump. And of course the main hydraulics come off a front PTO on the crank, so changing the main belt means unbolting the PTO coupling, which likely means removing the radiator. Hence deciding 800psi is good enough for now... :-)
Today I tore apart the spool valve again to chart out all of the oil passages, and I now understand completely how this thing works. Looks like it was entirely a problem with how it had been set up, so I'm about to head back over there to reinstall it using this handy chart:
Oh, and while I had it apart I went ahead and sleeved the end of the spool that was so worn and pitted. Much better now.
Actually, I think I'll go assemble it here in the basement as I suspect I'll have to make a new spacer or two to get the spool travel distances right. Nothing sucks more than having your tools scattered between two workshops, as the one you need is always at the other one... :-(
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WBraun
climber
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Thanks for the update adatesman.
I love your your stuff here .....
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tooth
Trad climber
B.C.
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And dont trust yer life to a load suspended by a hydraulic system.
The best advice when dealing with hydraulics. I had a full bucket decide to drop like a rock, it ripped the arm of my jacket on the way down, it was just luck that I wasn't any closer when it let loose - I would have been dead.
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 2, 2013 - 01:17pm PT
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Hey now... good thing I stayed home to put it together! Turns out that I need around 0.340" of spool travel to fully open the ports, and the way the spool's set up it only gets 0.150"! And that combined with the spool being incorrectly spaced to start with completely explains why I had a small amount of power yesterday one direction and not the other!
Here's a pic of how far it currently moves, which doesn't include all the washers, bushings, etc that actually limit the travel:
So yeah, sluggish, restricted hydraulics combined with immediately hitting the end of travel on the spool would completely explain why the steering was so heavy. New plan is to go machine the spool to accept a sleeve on the driven end to extend the length enough to allow full travel of the spool. After all, the slot for the driving pin is long enough to allow an inch of travel and there's no telling if this is actually the original, correct spool.
BTW, the full extent of the documentation I have on this is the following pic:
I'm really tempted to get the service manual, but it's $150 and I kinda doubt it would be much help for this (read: it'll say "replace part with a new one").
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 2, 2013 - 01:21pm PT
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And dont trust yer life to a load suspended by a hydraulic system.
Damned straight. Learned my lesson as a not-quite-teenager working in a machine shop with a 4000 pound rectangular forging hanging from straps on the crane. I didn't have it slung properly and the slings started slipping to center, and it put a 4" deep crater in the cement floor right where my brother had been standing. Quite simply: Never stand underneath *ANYTHING*. Also, machine shops aren't really the proper place for 12 year olds.
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hillrat
Trad climber
reno, nv
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Ah, different than I imagined. So the spool valve bolts to the end of the cyl with three bolts. Are the other two holes oil passages to feed the cylinder? Kinda eliminates the cyl test I described, having no access to the cylinder ports to cap them. Incomplete spool travel can definitely slow things down. Guessing one port on top of the spool valve is pressure, the other is return to tank. Where does steering input go into this thing? G46112?
Sure the ports at the spool are not offset a little differently?
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 2, 2013 - 02:42pm PT
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Hmm... Do you hear a whistling noise, Hillrat? Because that's the sound of your diagrams going over my head.
Ok, not quite... but close. This is my first foray into hydraulics and I have to say it's deceptively simple with a surprisingly steep learning curve. I suspect my problem is I'm completely ignorant of how to draw the diagrams, so no idea how to read them (I've got an excellent book on hydraulic system design from the 1970's, which left me even more confused than I was before I opened it).
That said, once I charted the valve out this morning it started making more sense and I think your #3 is the case (with the addition of an integral relief valve which is inaccessible inside the valve, due to a NLA cap I'm loathe to pop off since it's a press fit piece of aluminum and removal would destroy it).
My completely non-standard flow diagram looks like this:
And opposing views of the valve, including the drive pin:
Oh, and on the bottom pic- that ball bearing is swaged in tight to seal the end of the hole drilled for one of the ports. There's a bunch of them all over the valve body, but the rest are much, much smaller. The lighter colored plug is the aluminum cap for the relief valve, which the parts diagram shows an o-ring going on top of. Looks to me that this valve has been rebuilt to other than spec, but it seems to work to seal the port.
Oh x2- While the CAD drawings above aren't exact, they're good enough for government work as they were drawn to scale in Solidworks as I sat here with a vernier caliper measuring things.
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 2, 2013 - 03:12pm PT
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Hate to poke, Werner, but:
Thanks for the update adatesman.
I love your your stuff here .....
might be the first time I've even seen you say you liked something here on ST. I'm flattered!
:-)
-a.
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 2, 2013 - 04:28pm PT
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Hmmm.... So much for the "lengthening the stroke on the spool" plan. Looks like the stroke is limited by the housing and retaining washer, which allow only ~1/8" of travel. Weird, and has me wondering why they bothered making the slot for the pin so long.
I could get more travel by boring out the sleeve the pin is in, but dunno how much material would be left afterwards. And since the sleeve is clearly original, I'm hesitant to go that route. Perhaps 1/8" travel is all that's needed? And if so, that begs the question of why I didn't have any noticeable power to the cylinder yesterday, as I had the spool snugged up tight and close to where it was supposed to be and didn't see any pressure buildup when the pin was moved either direction....
Think I'll punt on this until tomorrow, as 8 hours on a Saturday is plenty for one day.
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hillrat
Trad climber
reno, nv
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Looking at the pictures helps a bunch. So, the spool is bolted solid to the housing actuated by the pin? Push pin left, spool goes left. Push right, spool goes right. Spring centered, always returns to center (neutral), correct?
As small as the cylinder is in relation to the valve body, and being directly attached, i'd say 1/8th is plenty of motion for the thing to work right. If you're uncovering the ports at all, you should get movement out of the cylinder. Most of the little ball bearing plugs are there for cross-drilling of passages, and yeah, you should really avoid removing them. Also avoid removing the pressed plug for the relief unless there's a way to verify that it's failed.
Remember that on a small cylinder like this, it only takes a very little volume to get a lot of movement, and fluid under pressure flows at a high volume.
The first two drawings represent what you'd likely see in an actual schematic, representing fluid flow. Ignore the first entirely, it's wrong. A reservoir is the only component that there are multiples of even though a machine only has one. (like Ground in an electronic diagram). On the spool valve schematic (2nd) there are 3 boxes that represent what the fluid is doing in the three positions of the spool and the paths the oil actually flows. In reality, the spool floats in between these positions with proportional flow in relation to how much effort you put in the steering and how far you move the spool physically.
The 3rd is like a generic cutaway of the internal guts of the valve, which should allow you to envision what happens as the spool is moved off-center and the ports connect. It's not exact either, but blue would be return to tank on that one, red is pressure, yellow and green are ports to the cylinder ends. I should have probably color-coordinated the lines on the 2nd drawing to match the third.
At this point, if you haven't got the cylinder apart yet, and you're pretty sure the pump is putting out flow (and thus pressure) then you probably ought to get the cylinder apart and replace the seals. Could be very likely that the piston seals are shot and the oil is simply bypassing the piston and flowing back the return to tank without moving it. If the seals are shot, you should be able to see that pretty readily on disassembly. Of course, this is not a gaurantee. Hard to diagnose from across the country. And I have no idea how hard all this is to perform from here.
I'm assuming, in saying that, that the spool is self-centering and firmly attached to the linkage like I asked above. Also assuming that the pump and relief are good at this point.
btw- your non-standard flow diagram looks spot-on.
How is this thing mounted?
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hillrat
Trad climber
reno, nv
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Ok. After re-reading this whole thing:
Your pump is rebuilt and producing up to 800psi. The steering system is separate from the main hydraulics for the loader/backhoe, and doesn't run anything else...?
You've mapped out the ports in the valve, pressure from pump at center, return on the outsides, cylinder ports between. Important to have the pressure/return hoses installed correct, as if they're backward they will exactly counteract whatever direction you try to steer, and the relief would not function at all.
You get lots of flow with everything running and in neutral (no steering input) so the valve is of "open center" design, meaning fluid simply passes through and returns to tank. Most gear-type pump systems run this kind of valve. That also means it's important to have a relief valve in the system so that when the cylinder bottoms out, fluid has a place to go. Gear pumps are positive displacement, meaning for every revolution they move a fixed volume of fluid. This by itself only creates flow. When you restrict flow, like closing a water faucet, pressure goes up. Without the relief, you end up finding the weak link... like slipping belts, blowing hoses, etc.
So if you have flow from the pump and the belts hold enough to create pressure, the plumbing is correct, and the spool is shifting side to side enough to open ports and divert fluid flow to the cylinder, we narrow down the possibilities:
1. The piston seals in the cylinder are shot and fluid is bypassing it, simply flowing through and back to tank.
or
2. The relief valve is stuck open or the spring is weak/broken essentially causing the same effect, allowing fluid to flow through it and return to tank at low psi when it should be moving the cylinder rod instead. Sucks it's under the swaged in aluminum cap.
The whole thing is kind of interesting in design, but without hoses between the valve and the cylinder it's a little harder to check things out. At least that part makes it impossible to cross the lines to the cylinder. Anyway...
relief valve, briefly... pressure acts against the check ball, which is held in place by a spring. When pressure overcomes spring force, the check ball/poppet/plug moves off its seat and allows fluid to flow by. on the right is a schematic representation of a relief valve. Fun stuff. You'd be amazed how a check ball the size of a BB can shut down an entire machine if it gets hung up. And in a fixed displacement pump system, the relief has to handle full pump flow, so if it's stuck open, there goes your pressure.
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 3, 2013 - 01:07pm PT
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I think we found it Hillrat... At least, I'm 100% certain it can't possibly work the way it is currently and have something to fix.
But first, you asked how the thing attaches... In a nutshell, one end of the steering cylinder bolts to a bracket on the front axle, with the other end bolted the steering by way of the pin on the spool valve.
I got thinking about your post from last night and agree; it's got to be a problem with either the rod seal or the relief valve. And given it was 20 degrees out, I opted to drilling out that aluminum plug on the relief rather than heading over to the other house to take apart the cylinder.
Good news is that the aluminum plug will be easy to replace, as it's literally just a plug with an o-ring. New one will take all of 5 minutes to make, and I'll likely drill and tap the one side for a small screw to make removal easier in the future.
This also got me access to the relief valve, which now that I see it I can't imagine how this could possibly work as there's no spring to bias the ball and the oil is free to flow through unrestricted.
What this leaves me with is effectively this:
The way I see it, there's two options:
1. Make a new relief valve that incorporates a spring
2. Say screw it and plug the bypass, relying instead on either the relief on the pump to open or the pulley to slip.
Much as I'd prefer Option 1, I think I'm going to go with Option 2 because the relief in the valve only comes into play at the end of steering travel and because the pump's only putting out 2/3 of its rated pressure (should be 1200psi or so, but the pulley slips at 800). Plus making a plug will take 20 minutes or so, while a new relief will take the better part of the day (calculations, followed by machining, followed making the tooling to wind the spring, followed by actually winding it). The way I figure, if the plug works then I can decide whether to fix it properly or not.
BTW, I haven't yet looked at Grainger to see if they have a relief that will fit, but McMaster didn't.
Anyway, lunchtime!
-aric.
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TGT
Social climber
So Cal
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There's no spring in the exploded diagram.
Sure that isn't a check valve?
If it was a relief valve and had a spring in it, bits of that spring would have to be somewhere.
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 3, 2013 - 01:56pm PT
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Sure does look like a check valve, and there's no evidence of a spring anywhere. That said, the o-rings were in fairly good shape so there's a decent chance it was rebuilt at some point (and possibly parts omitted, although there doesn't look to be any missing per the diagram).
FWIW, the parts diagram calls that bit a "Valve, Relief w/ Ball". And with nothing keeping it closed there's no way to build any pressure in the system short of overwhelming it with volume, which the small steering pump simply wouldn't have the flow for. At least, that's what I make of it....
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 3, 2013 - 04:49pm PT
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Well, lost the bulk of the afternoon to playing with our little one (Helen, 2-1/2) while my wife took a much needed nap, so only got as far as machining the plug to replace the check/relief valve and a new aluminum plug to seal the passage, as well as getting it all assembled.
Pic of the replacement parts, and kindly excuse the overly-large slot on the plug... I already had a 1/8" endmill in the spindle of the milling machine and got lazy. Oh, and I upgraded the aluminum piece with a #6-32 tapped hole to make removal easier next time (happen to have a bunch of #6-32 stainless bolts handy, as well as the tap).
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I'm sure I mentioned it elsewhere, but I'm *REALLY* loving this lathe. It's an old Clausing 5900-series (5917 to be exact), probably 1960's vintage, and 12" swing x 36" bed. Was an "upgrade" to my Atlas 12"x36" last summer (or the one before?), if you can call it that.... The Atlas weighed ~250 pounds. The Clausing is north of 1200 pounds, with the same work envelope. An absolute joy to use in comparison (not to say good work can't be done on the light and flimsy Atlas; just that it's easier and more enjoyable on the much sturdier Clausing). It's in the background of one of the pics above where I have the spool in the bench vice.
Man, I really wish they still taught this stuff in the general curriculum in schools.... Being able to make things is an important skill that everyone needs to have a degree of exposure to, IMO.
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hillrat
Trad climber
reno, nv
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Wow. Yep, the relief valve without a spring would be nothing but a check valve. That spring pressure is what the hydraulic psi has to overcome for the valve to open, and if you got no spring then you got no pressure.
Wouldn't it be nice to throw it back together and have the thing work?
Just don't tighten that belt too much or you'll find the weak link!
Sure is nice to have a lathe eh? I've got an antique (1917 or so?) Walcott in the garage. Too bad it's missing the 1 1/4x6tpi leadscrew and a motor. It was a basket-case when I bought it, so I'm making progress. Meanwhile, I went chukar hunting today. Football? What's that?
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AP
Trad climber
Calgary
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Never stand beneath a hoisted load. Damn right.
I was working in a pipe mill many years ago and the Pettibone operator came in to the shop after a near accident. He had stopped his machine and got out to throw a piece of lumber out of the way of where he was going to set this big scrap bin of steel. The hoist failed, bin crashed down and missed him literally by a hair. His jeans had a 6 inch rip from crotch to upper thigh.
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bajaandy
climber
Escondido, CA
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Man, I really wish they still taught this stuff in the general curriculum in schools.... Being able to make things is an important skill that everyone needs to have a degree of exposure to, IMO.
Not that I can help you with your hydraulics, but you'll be happy to know that we still have a fully functioning set of shop classes at the high school where I teach. We've got two machining classes, two fabrication classes, five woodworking classes, two construction trades classes, one CAD class and one Architecture class. The drafting and wood are my babies, with another instructor for the metal side of the show and one more instructor for the trades classes. In this day and age of schools closing shops left and right, it feels good to work in a district that sees the value of CTE.
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WBraun
climber
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"Being able to make things is an important skill that everyone needs to have a degree of exposure to, IMO."
Just see
A real Yankee, with ingenuity ......
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 4, 2013 - 04:14pm PT
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Not that I can help you with your hydraulics, but you'll be happy to know that we still have a fully functioning set of shop classes at the high school where I teach.
Absolutely ecstatic to hear it, in fact. Way too many of these programs have closed down due to liability issues...
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 4, 2013 - 04:29pm PT
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Well, looks like perfectionism got the better of me again and I spent the day making a new relief valve anyway. I had given up on that approach when I couldn't find a spring anywhere near strong enough that would fit (less than 0.300" OD, 1" long and 30 pounds of force), but this morning I had a realization... The pressure on the ball bearing seal is a function of the size of the hole in front of it, so if I make that hole smaller I'll be able to use a much more reasonable spring.
A quick flip through the McMaster catalog didn't turn up anything, but Grainger sure did... 0.300" OD, 13/16" long, 11.9 pounds of force when compressed to 0.413". Plenty of physical space to fit that in the relief, and if taken all the way to 11.9 pounds of force would make the valve open at ~1500psi! Perfect!!!
So went ahead and ordered that spring and then machined a new relief valve, sporting a much longer body to make room for the spring:
Should be pretty self explanatory except for the little tabs on the back end... I figure I'll put a spacer inside behind the spring to compress it and then fold those tabs inwards to keep everything in place . Much simpler than trying to figure a threaded connection back there... Oh, and the cross-drilled holes are because this valve crosses in front of the main return line and I figured it best to reduce any restriction there.
Anyway, the spring will be here on Wednesday, so guess I'll have time to poke at the main hydraulics a bit... Will update this in a couple days to say whether the repair worked or not.
Thanks for all the help Folks! And Hillrat especially!
-aric.
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FRUMY
Trad climber
SHERMAN OAKS,CA
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adatesman It is an absolute pleasure watching you work through this.
Hillrat you are a treasure.
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hobo_dan
Social climber
Minnesota
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This is better than the super bowl--What's next? Did it work?
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 4, 2013 - 09:40pm PT
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Thanks Frumy. Aside from the freezing temps and deadline, this has been quite an enjoyable project.
And yes, Hillrat's quite a treasure!
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 4, 2013 - 09:44pm PT
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Hobo-Dan- the spring won't be in until late Wednesday, so I won't know if it works or not until Thursday. I do have a nice pile of all sorts of sizes of spring wire sitting here (in both carbon and stainless), but simply have no interest in going through the iterations it takes to find the combination of wire size, mandrel diameter and coil spacing to get what I need. There's a day of trial and error right there, and when I can get a pack of them for $6 and have oodles of other work to do it's just not worth it.
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hillrat
Trad climber
reno, nv
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Well, I'm quite a something-or-other, but treasure maybe giving me a little too much credit. Now if you'd asked me about office management or something, that'd be outa my league. Just hoping the thing works for ya.
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hillrat
Trad climber
reno, nv
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Hey, if this all works out and the thing gets fixed, would you mind if I used this thread for a real-life example in the class I'm about to teach? I think the students could benefit from it. I'd leave out names and alter the content somewhat, so that it can be presented as a problem that they have to work on solving kind of along the lines of what we've been doing here.
Curious as to how this thing turns out when it's all said and done too.
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 7, 2013 - 11:34am PT
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Ok Folks, the moment of truth is upon us. Picked up the spring for the relief valve this morning and finished it off, and by my calculations it should open around 1000psi. Heading over to install it...
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Bill Mc Kirgan
Trad climber
Cedar Rapids, Iowa
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Adatesman, I hope you get that rig running soon. I'm so impressed with the Old Schoolhouse project you've started, and am rooting for your success.
I can't help any, but...jes want to say
This thread is just more proof the the Taco is becoming the great repository of all that should be known about the universe.
On matters of the building trades, or computer repair, programming, photography, cooking bacon, coffee, car repair, chocolate, boat building, beer, MUSIC, ...whathaveyou? I tend to search the Taco first before resorting to the Google box. I don't think I'm the only one making this transition.
Very impressed with the power of the Taco.
Good luck with the hydro repair so you can get to trenching and frenchin' and stabilize the humidity and protect the plaster work in that amazing structure.
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Ferretlegger
Trad climber
san Jose, CA
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Hi guys,
This has been interesting to watch unfold. I hope the new solution works. For those with an interest in machining, especially "old school", and who enjoy crusty craftsmen at work, here is a link to Keith Fenner's page of (hundreds) of Youtube videos of his work. http://www.youtube.com/user/KEF791/videos?view=0. He is a real joy to watch and very generous with his advice and time. Beware: you may not get much sleep after you start watching these!!
Michael
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 7, 2013 - 02:19pm PT
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First the good news- the backhoe's reassembled and it not only builds steering pressure when cranking over, but the wheels move!
The bad news- it didn't like sitting the past couple days and it refuses to start.
So close!!!!
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hillrat
Trad climber
reno, nv
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nice! try not to hold it over relief if you can. theyre usualy designed to handle full pump flow, and with the smaller hole it would be somewhat less. shouldnt be a problem as long as you dont keep it cranked to the stops.
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 7, 2013 - 02:56pm PT
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So close!!!
Got it running finally (forgot I had turned off the idle circuit in the carb), and it keeps a steady ~850psi to the steering valve. Even better, it will turn the wheels when parked with just a single finger on the steering wheel (which is a major improvement from not being able to turn it at all with both arms before).
Thing is, it only steers in one direction. And the direction is almost random, and based on the position of the spool at startup. Going to have to think on that.
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 7, 2013 - 03:08pm PT
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Hmmm... I think I follow, Hillrat.
And actually, I think we might have missed something that explains the goofy behavior. This diagram from before is based on actual measurements of the spool valve (read: relative positions are within a couple thou...), and looking at it again I'm not seeing how it isn't deadheading the pump if the relief is closed.
.... Which leads me to think that the problem wasn't a springless relief valve, but rather modern power steering fluid being a lot less viscous than the original "transmission fluid" called for and not seeing any restriction from the orifice in the original "relief" valve.
Easy enough to test this theory by removing the relief and splicing the gage and ball valve into the exhaust side of the spool valve (and use the ball valve to throttle it down/build pressure).
Not sure if this explains why I can't switch directions though...
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 7, 2013 - 03:32pm PT
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A couple more clues... I'm 99% sure the spool is deadheading the pump and the new relief is not opening, as there's no flow apparent in the reservoir. If either the relief opened or the spool not deadheading, then there would be flow apparent. Additionally, closing the ball valve I have on the output of the pump has no effect whatsoever on the output pressure, so I'm pretty sure the 850psi I'm seeing is the max the pump is capable of (whether in total or by way of its relief valve).
As such I'm really beginning to think this whole mess is an oil viscosity issue rather than something mechanical. Any thoughts, Hillrat or anyone else? Seems to me that finding the right size orifice for the flow/pressure and fluid I'm using would be a simple matter of looking it up on a chart. At least, I hope so as I did terrible in fluid dynamics and really never want to open that book again.
Heading out of town for a couple days, but will be back on this Monday AM.
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 7, 2013 - 03:41pm PT
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Scratch that.... Can't mock it up by throttling down the exhaust port... That would leave no pressure differential to work the cylinder. Crap.
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hillrat
Trad climber
reno, nv
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i almost think its possible that pressure and return are backward at the inlet-
that would cause the cylinder to put more pressure on the valve in the direction it was steering and cause it to run to the stop.
Normally, when you move the wheel it opens the valve until the steering moves enuf to center the valve at which point everything would stop.
by your drawing, it does look like a closed center valve, which would mean pressure runs over relief all the time in neutral. Odd. have to think on that.
in any case, viscosity really shouldnt be a major issue here, and transmission oil vs power steer oil shouldwbe simikar viscosity anyway.
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 7, 2013 - 05:31pm PT
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Yeah, this sure seems a goofy way of doing it. Certainly would explain why they went to the more typical steering-column-mounted rotary setup a couple years later... Then again, the earlier models were all manual steering and this was certainly an easy way to graft power onto it. Unfortunately this model fell right after the change from manual steering, so does not have the steering box geared down far enough to make it work without assist.
Anyway, I just picked up the little one from an overnight at the in-laws and she's completely zonked, so pardon my talking this through while parked in the driveway...
If we assume that the valve is indeed a closed center (thx for the proper term!), then clearly there needs to be a restriction of some sort between the high and low sides to create the pressure differential to work the cylinder. Assuming the original springless relief was correct, it had to be relying on the combination of flow and orifice size to build pressure. From what I've read, the pump was rated at something like 1200psi and 6gpm, but best I can get it is 850psi at an unknown flow (don't have a way to measure it). Clearly the original combination of flow/orifice isn't working, as it wasn't building any pressure after rebuilding the pump. So I guess that leaves me guessing at what pressure it needs to run at, and then decide whether to obtain it by way of sizing of the orifice or spring pressure on a relief valve.
I'm thinking a spring loaded relief is a better option since it'll be relatively constant as the fluid warms, but a sized orifice much simpler.
Hmmm....
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 7, 2013 - 05:33pm PT
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Btw, Hillrat, absolutely feel free to use this in your class! Quite the interesting problem, having to reverse engineer everything to come to the solution. I probably even have more pics and a video or two of remachining the pump...
Oh, and what's the class?
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hillrat
Trad climber
reno, nv
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heh heh..
class is hydraulics.
Hard to say, this whole thing may not be original configuration, and it could be that smeones mixed and matched parts that dont fit together. Gear pump systems almost always use open center designs, unless its tied into the main hydraulics with a priority valve. Constantly ruming over relief in a closed center like this is going to build lots of heat, which will be bad in short order.
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 7, 2013 - 06:25pm PT
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Ha! Kinda figured hydraulics, was meaning more high school/college/etc. :-)
Fwiw, the pump, cylinder and spool valve body all appear to match the depictions in the parts manual (and/or have the correct numbers cast on them). Unfortunately no way to tell on the spool or it's relief, but it's clear someone had been in the pump at one point and did it correctly.
Little one's now awake and watching a movie, so currently throwing some dimensions on some pics to try and make sense of this (and prove one way or another if it's closed center).
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 7, 2013 - 07:18pm PT
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Well, looks pretty decidedly like a closed center valve. Sorry about the goofy dimensions; it was a quick and dirty with a caliper (really doubting that 0.160"). And I've skipped a couple versions of my CAD software and haven't yet figured out how to get this one to do what I want it to, so gave up did it in MS Paint....
Not pictured is a pair of very small chamfers on 2 spots of each side of the center lobe of the spool (orange dots). At most they're 0.015" wide x .100" long, so nowhere near enough for much fluid flow. No chamfers on the other spool lobes. Oh, and one very small (~0.050" dia) hole going underneath each lobe on the spool, connecting the chambers on either side (brown lines).
EDIT- Occurs to me I never posted a pic of the pump... This is after an attempt to stone out the cupping in the mating surfaces, which didn't help with the pressure issues. The cover was subsequently drawfiled/stoned flat and the other piece turned flat and the bore for the gerotor remachined in the lathe, which helped immensely pressure-wise. Oh, and a completely new pump shaft was machined out of some A2 I had in the drawer.
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hillrat
Trad climber
reno, nv
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Were there any valves in the pump?
I don't see any discrepancies in the parts pictures you've got. All looks pretty straight-forward as to how it should be working. Basic kinda system. But I don't see any alternate flow path for the oil in the closed center system, which is weird.
I should have been more clear earlier... if the pressure/return were backward, it would steer in the opposite direction of steering input.
And I see there's a relief in the pump, just wondered if it's a straight relief or if it's something else.
It's a college class. I work as a mechanic by day, and teach a class once in a while part-time. Fifth class so far, 2nd hydraulics class. They've got a bunch of old books (or had some anyway) but i don't know if there's any on this thing. Was supposed to go up there today, but we've all been sick here, so haven't made it.
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 7, 2013 - 08:21pm PT
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Seems I didn't take pics of the finished but not yet reassembled pump. Oops. Here's the back of the housing though, which should make the relief fairly obvious... Basically just a linear valve that connects the high side (output is the flare fitting at the top) to the low side when the pressure on the high side becomes too great. Other than the relief and gerotor, the only parts are o-rings, bearings and the 2 halves of the housing.
And yup, steering direction was correct. Just that it wouldn't reverse without shutting down the engine and repositioning the spool.
Cool about the part time teaching gig. Would think that rather rewarding. Bummer about being sick though.
Oh, and:
But I don't see any alternate flow path for the oil in the closed center system, which is weird.
This is why I was thinking along the lines of the relief valve orifice size/oil viscosity thing. Nowhere else for the fluid to go, other than a small amount to cycle through the pump or the entire volume to cycle through the spool relief. Neither are great options, but the former much worse than the latter.
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WBraun
climber
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This is awesome guys.
Thanks so much for updating and good luck.
I love this stuff and I'm learning from you guys ....
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 7, 2013 - 08:42pm PT
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You're not the only one learning, Werner. :-)
Hillrat must be one heck of a teacher, given his willingness to put this much time into this for me. Thanks again, Hillrat!
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hillrat
Trad climber
reno, nv
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so the relief in the pump is the same style as the spring/ball/seat as in the steering valve? Must be quite a bit larger then...?
Steers in the correct direction, but won't return until engine is shut down. There's no way pressure is getting in behind the end of the spool is there? Leakage, etc? I would think the cavities at each end of the spool should not have any oil in them, or should be vented to the atmosphere somehow so you can't develop a sticking spool somehow.
I'm the guy who hides in the back of the class, so teaching is a continual challenge. And if you want to learn something, try teaching it. Or, you know, threads like this. ha!
You don't have the parts diagram for the pump itself by chance?
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TGT
Social climber
So Cal
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From looking at your parts drawing, the spool is held by hydraulic pressure against the rod that connects to the steering linkage and there's nothing other than hydraulic pressure that keeps it shifted in one direction against the spring.
Am I seeing that correctly?
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 7, 2013 - 09:01pm PT
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Did I not post diagrams for the pump and reservoir? Yikes! Sorry about that!
EDIT- May as well put the other diagrams here as well so I don't have to keep flipping pages...
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 7, 2013 - 09:07pm PT
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Am I seeing that correctly?
Near as I can tell, TGT. Then again, I can't for the life of me figure the purpose of that contraption the steering pin in the spool valve assembly does... There's a spring that keeps the pin captured between the seats and it's a threaded connection to allow the tension to be set, but no way to keep the tension set other than bottoming out the threads. Plus the spacers only allow 1/8" of movement yet the slot for the steering pin is almost 2" long... ???
But yeah, in the diagram of the steering cylinder the pin (part G46112) is held inside part G46109 with a seat on each side and the spring and plunger (parts G46113 and G46115) on the open end. Part G46108 then screws into part G46109 and is connected to the spool by way of the bolt that passes through it prior to screwing in.
Doesn't make a whole lot of sense to me, and were it not for the fact reprint of the Service Manual costs $150+ (and would likely just tell me to replace everything with new) I'd have long since ordered one. Although at this point the frustration level is getting high enough to just order it in hopes it solves the problem....
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hillrat
Trad climber
reno, nv
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G45084 on the top right... that's the relief assembly, right? Is that whole big cartridge mobile in there? It looks like there might be a smaller valve as part of the assembly, and with a couple springs like that, I wonder if that's a pilot operated style full-flow relief assembly that recycles back to the inlet side of the pump?
In that case, it maybe designed to maintain working pressure to the steering valve without sending full pump flow through the small relief on the valve. In which case the failure to steer properly would more or less indicate a sticking steering valve somehow.
Just to verify, the steering input and the valve spool are physically connected... solidly. I see a spring in the (for lack of better term) cartridge (g46109) that the steering input goes in, with the two cups and the spring behind it in the cartridge. So this is all actually bolted to the spool correct?
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hillrat
Trad climber
reno, nv
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Aha... if the spool is not bolted to the steering linkage, this thing wont work.
Bolt through g46108 connects through spool with an nut on the end. G46108 should be connected to g46109 or when you steer right (I think) that 46109 assembly pulls away from the spool, spool stays put, when it should be pulling the spool back to neutral. Or to the right, if you're trying to steer that way.
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 7, 2013 - 09:22pm PT
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TGT- that link makes my head hurt. :-)
Hillrat-
G45084 on the top right... that's the relief assembly, right? Is that whole big cartridge mobile in there?
Here's a better pic:
Yup, part G45084 floats freely in the bore, and is held in place (biased to the low side) by the spring that bears against the output fitting. I did not take G45084 apart, but did clean it out real good with brake cleaner and verified the valved opened when pushed on.
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 7, 2013 - 09:30pm PT
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G46108 should be connected to g46109
I'm afraid they are... The spool is bolted to G46108, and G46108 screws into G46109 against the spring pressure of G46113/G46115.
The whole thing then works by the G46112 pin making the G46108/G46109/spool assemble move relative to the valve body and the G14452 housing. The spring seems to only have an effect in one direction, oddly, and as I mentioned there's only 1/8" of travel available to the spool in spite of how big that slot is. Seems to me allowing more travel would make centering the spool on assembly less critical, so why have so big a slot if it's not used?
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 7, 2013 - 09:39pm PT
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In that case, it maybe designed to maintain working pressure to the steering valve without sending full pump flow through the small relief on the valve.
Perhaps, but that doesn't fit from the perspective of the original spool relief valve not allowing the pump to build any pressure (but allowing gobs of flow).
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 7, 2013 - 09:41pm PT
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Ok Guys, calling it a night here. I've got the little one in the morning, so gotta turn in.
Thanks again!
-aric.
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hillrat
Trad climber
reno, nv
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Well, all right. The steering assembly sounds like it's bolted firmly to the spool. I'd guess that spring is just to keep everything nice and tight on the input pin, maybe to account for wear, etc. Really, the spring should probably have no net effect.
If the original relief in the steering valve is big enough to handle full pump flow, it would explain what was going on for the full flow you were seeing in the reservoir, especially if the relief in the pump is the pilot operated type relief designed to dump full flow and just maintain the working pressure, which the steering valve relief would not be designed to do.
I borrowed one of your valve cutaways you drew. Where I added the light green arrows,
if there are no hydraulic ports to those end grooves on the spool, then it is not hydraulically actuated, and I'd be surprised if it was. More likely, there may be vents to atmosphere or possibly to return. If it's just a dead cavity, then accumulation of leaked oil and/or vacuum there could stick the spool in an applied position.
Centering the spool on assembly should really not be required, since as soon as the engine is started and pressure reaches the valve, the assembly should be self-centering as it would send pressure to move the steering until the valve centers and lack of pressure would stop to the cylinder.
Any chance there's some mechanical binding going on? I mean, now that you've actually got funky power steering, the thing's moving. So we have pressure, and some funky steering. Gettin closer. I assume zero chance of the spool being flipped. I'm probably missing where the spacers and stops are that limit spool travel, and just kind of wondering if they're factory or someone was messing with it. Uncovering the ports only halfway should only really slow down operation, not cause the symptoms you describe.
So, 46115 is just a retainer for the input? The spool, 46108, 46109 constitute a solid assembly, and the spring 46113 only buffers movement of the input pin within 46109 right? The 46109 assembly, with spool etc shouldn't bind up in the housing when assembled. Wondering if that's going on.
Not sure I'm not just getting tired after a long day at work and having been sick recently. Yawn.
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 8, 2013 - 11:56am PT
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Did a bit of digging, and found a handy chart for pressure drop of oil flowing through an orifice:
The pump is supposed to put out 6gpm, so with the orifice in the original relief valve being just shy of 7/32" diameter it's not surprising there wasn't any pressure buildup.
On the relief valve I made, I quite arbitrarily drilled the orifice 0.100" diameter, so between 3/32" and 7/64" diameter. Looks like if the pump is putting out 5gpm or over the spring might not be needed to put me in the ballpark pressure-wise. Think when I get back on Monday I'll drill the plug I made a hair under 3/32" and then give both that and the other relief (minus the spring) a try after attempting to get a ballpark of the flow rate.
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 8, 2013 - 12:05pm PT
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So, 46115 is just a retainer for the input? The spool, 46108, 46109 constitute a solid assembly, and the spring 46113 only buffers movement of the input pin within 46109 right? The 46109 assembly, with spool etc shouldn't bind up in the housing when assembled. Wondering if that's going on.
Yup, just a plunger in the end of the spring to let it bear on the spool bolt properly. I made sure to deburr everything and check for proper movement before reassembly, so I don't think there's binding going on.
More likely, there may be vents to atmosphere or possibly to return.
Another Yup, there's a small tube through each lobe on the spool to connect the cavities on the end to the ones between the lobes. Think I marked them in brown in one of the other drawings.
I'm probably missing where the spacers and stops are that limit spool travel, and just kind of wondering if they're factory or someone was messing with it.
Not missing them, but rather they're oddly implemented... They're actually in the spool assembly we were talking about, and are parts G49035 and G46108. In one direction G49035 runs into the valve body and the other direction G46108 runs into the G14452 housing that the assembly slides in.
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hillrat
Trad climber
reno, nv
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Spacers are supposed to be there then. You cant just leave them out and increase spool travel. Steerings not biased one direction or the other? Said before it was random, based on spool position at assembly. Man this would be easier with pressure taps at both cylinder delivery ports for a gauge.
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hillrat
Trad climber
reno, nv
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I didnt see the link in brown to vent the spool ends. By going to the ports in the grooves on the spool, you mean the low psi return, not pressure or cyl delivery i hope. Psi acting on spool ends would be another headache.
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 8, 2013 - 01:22pm PT
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Quick hit&run as we're just about out the door...
Here's a more complete diagram, which shows the orings and spool bushings. The brown lines under the top of each lobe on the spool are the small holes that connect each side, and the purple lines are the output-to-the-cylinder passages in the valve body (those lines are not in the spool).
Ok, gotta jet if we're to miss rush hour DC traffic....
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hillrat
Trad climber
reno, nv
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Dumb question of the day-
The cylinder rod is hooked to the frame and the valve end to the steering knucle, right?
Those ports look familiar. I glossed over them before. Really small holes? kind of tryng to make sure those are not pressurising the end of the spool and holding it in the applied position. Looks like what i take to be main relief at the pump is not adjustable. About to the point of throwing arms up in the air in a I-dont-know posture. I think i undestand the theory of operation here, but its doing somethn weird. And about all i can think of left is to pull the cylinder apart and make sure the piston seals are good.
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 8, 2013 - 01:46pm PT
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Not a dumb question, and yup. G13942 (in the overall system pic) goes from the steering box to the G46112 pin in the spool assembly, and the end of the G14452 housing the spool assembly slides in connects to G45057 tie rod and the G16667 steering lever. The cylinder end bolts to G1282, which is bolted to the front axle.
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 8, 2013 - 06:25pm PT
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What's the fun in buying replacement parts? Besides, when I priced a power steering pump at the start of this, they wanted over $300 for a salvaged, as pulled, not tested, no guarantee pump. Seeing as I paid $2600 for the whole thing, I don't think replacement parts are worth the cost when most everything is rebuilable with simple tools.
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GhoulweJ
Trad climber
El Dorado Hills, CA
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Ok cool.
I run a wholesale tractor parts company with locations around the world.
I've listened to hundreds of stories like this resulting in buying a part anyway.
I would pay $300 for the part. Seems cheap enough.
That tractor has low resale value BECAUSE of the high price of parts for it so I do understand wanting to avoid expense.
I just put more value on my time than that. Just a pesrsonal choice.
Good on ya for determination, but these tractors can drive u MAD!!!
Oh how I know (said while shaking my head at myself).
Good luck bro
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 8, 2013 - 10:04pm PT
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Part of the problem, GhoulweJ, is that they only made this line for 2 years (4 if you include the mostly-similar 300B series), so they simply didn't make all that many of them in a relative sense and used parts are scarce (and therefore spendy). Fortunately everything on it is pretty simple and straight forward, so it's a good match for my love of tinkering. Case in point, first thing I did upon getting it home was cut out bad repairs on the lower swivel of the backhoe.
This pic was from partway through the exploratory surgery to see how far up the crack went. In the end all of the plates were cut off and that corner weld removed.
And then it was forced back into proper alignment and fixed properly. Both sides needed to be done, and all told it took ~12 pounds of rod (6011 for the roots, then fill with 7018).
Probably shouldn't be surprising that until the little one came along my daily driver was a '66 Volvo 122 and 'fun car' a '59 Triumph TR3 (which had also been a daily driver for a while). So yeah, this backhoe might drive me mad, but it was bound to happen anyway.... :-)
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hillrat
Trad climber
reno, nv
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Kinda concerned this might be going on, but really depends on how big the holes are from one side of the spool lands to the other and whether there's any leakage past the lands back to return. If enough pressure builds up on the end of the spool, it could lock it in place in the applied position.
Edit: this is the valve as you've depicted it. After thinking more on it this morning, I've flipped the illustration, deleted another post where I was working out operation, and added a new one this morning below.
This post is I think what's happening now, thinking the pressure/delivery are crossed, and the delivery to the cylinders I think is wrong as it would be depicted here. Please see the next post, as I think that's what actually should be happening.
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hillrat
Trad climber
reno, nv
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Ok. Thought it over a bit. I think maybe the diagram showing hoses etc is backward. Try reassembly with the original relief in the valve body... I don't think it's actually a relief. I think it's a check valve, intended as a check valve to enable steering when the engine is off or the pump fails.
Reassemble, and reverse the pressure/return hoses and what you may end up with is this:
If in fact pressure and return have been reversed this whole time, you'd get many of the symptoms of poor steering you've been fighting, as the pressure on the end of the spool would be locking it in the applied position. that would cause the assembly to be dependent on spool position as of assembly. Further, the way it's built, when the engine is off and there's no flow in the system, the cylinder would act as a pump, and the check valve would allow oil circulation so that the system wouldn't get hydraulically locked. Even further, in this last configuration, you're steering against the pressure acting on the end of the spool which is trying to center it. So the more force you put on the wheel, the further the spool would travel and the faster your steering would work. This makes more sense to me now. I hope.
Damn if that wouldn't be a trip if all this time the whole problem was crossed lines. For that matter, without full disassembly/assembly you could try crossing the lines first, then if it works, change out the "relief" so it works if the engine stalls.
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hillrat
Trad climber
reno, nv
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Feb 10, 2013 - 12:10pm PT
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Couple more thoughts. If you swap lines so the "relief", which I think is actually a check valve, so that it stops pump pressure from flowing through it, then you shouldn't see any flow back to the reservoir in neutral.
Also, and I wish I'd thought of this before, if you can see flow in the tank, then you can check the cylinder seals that way. Bottom out the steering either right or left, and hold it there continuing to put in steering effort. You should see no flow coming through to the tank. If you do, then you need to reseal the piston.
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 10, 2013 - 11:51pm PT
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Hillrat, you really are a treasure. Thanks so much. No matter how this ends up, got we've got a little something tasty in mind to compensate for the trouble you've gone to. Kindly drop me your snail mail address when you get a chance.... BTW, this is Helen, otherwise known as thelittleone, who is very much looking forward to having her own "digger" that she's "going to drive and Daddy's going to fix". She's not even 3 yet, and I already can't wait to teach her to weld. :-)
As for your posts over the weekend, well.... Much as I agree it makes no sense for there being a check valve that never closes, it also makes no sense for a parts diagram to show an incorrect hose connection and not get updated sometime over the intervening 60 years. Which is to say it doesn't surprise me in the least that this might be the case, given what I've seen on the similar-vintage cars I've had over the years. That said, once I get back over there I'm going to hold off on swapping the hoses because I suspect the bushing I made for the far end of the spool wasn't long enough and allowed pressure to build at the end once the bushing slipped past the end. There is a ~1/4" deep bore in the end of the cylinder for the bushing which had been taken up by an o-ring, but I instead made a bushing that fit properly and looked like the one depicted in the parts diagram. In hindsight given the passages under the lobes on the spool I can see that bushing being forced off an getting jammed at the end, so want to pull it apart and see what happened.
Basically another example of why it's a bad idea to have your tools split between 2 workplaces... all of my wrenches are with the backhoe, which means the one I need when working on the pump at home isn't there, or when I'm over there the measurement tools for this sort of thing are at home.... Which leads to "just machine it to half a thumbnail long", which may or may not work. :-(
Anyway, will be back on this as soon as I can, and frankly I'm liking the hoses-are-reversed answer. But I also liked the "make a new valve with a spring" answer... :-)
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 12, 2013 - 01:16pm PT
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HOLY CRAP!!!!!!! IT WORKS!!!!!!!!!
Hillrat- looks like you were right! The parts diagram shows the hoses reversed! The only thing I did today was remove the spring from the valve I made (0.100" orifice, left the ball in place) and swapped the input and exhaust lines. Pressure stays low with the spool centered and jumps to 600-800psi when moved to either side. And even better, it's possible to turn the wheels while parked on concrete!
Woo-frickin-HOO!!!!!
I'm kinda curious whether it would also work with the hoses hooked up as shown in the diagram, but no way I'm messing with it further.
THANKS SO MUCH EVERYONE!!! And Hillrat in particular!!!
-Aric.
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FRUMY
Trad climber
SHERMAN OAKS,CA
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Feb 12, 2013 - 01:21pm PT
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Hillrat -- you are a treasure.
Glad to see both of you stuck with it till it worked.
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WBraun
climber
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Feb 12, 2013 - 01:26pm PT
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Victory !!!!
Awesome !!!!
And another special thanks to hillrat ........
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 12, 2013 - 01:32pm PT
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Oh, and Hillrat- please pm me your snail mail address.... I really would like to send a proper thank you. :-)
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bajaandy
climber
Escondido, CA
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Feb 12, 2013 - 01:36pm PT
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Ah! The sweet taste of VICTORY! (Although in this case it tastes a bit like hydraulic fluid, I bet.) Glad you got it working.
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hillrat
Trad climber
reno, nv
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Feb 12, 2013 - 01:38pm PT
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Hey- sweet! Not the first time the book has been a little off. Good luck with your project. No special thanks needed, it was a fun little mystery. All the same, I,ll pm you.
My little germ-catcher-
Someday soon she,ll start talking. Then the real fun begins. Lookin forward to when she can walk and talk and tell me things, like yours is doing. Changes yer life, eh?
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adatesman
climber
philadelphia, pa
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Topic Author's Reply - Feb 12, 2013 - 02:24pm PT
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Coolness.. I have no doubt you'll like it, Hillrat, and there's a hint in the pic of our little one as to what it is. :-)
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TGT
Social climber
So Cal
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Feb 12, 2013 - 02:35pm PT
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Hey- sweet! Not the first time the book has been a little off.
In the 70's Fiat's were famous for blowing head gaskets all because of an incorrect torque figure in the manuals.
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hillrat
Trad climber
reno, nv
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Mar 10, 2013 - 03:42pm PT
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adatesman-
Thank You for the gift and the recipe! We finally got a free morning, and it was the perfect start. Hope all is going well for you!
John
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| Messages 1 - 95 of total 95 in this topic |
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