OT: hydraulic help needed!

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Messages 61 - 80 of total 96 in this topic << First  |  < Previous  |  Show All  |  Next >  |  Last >>
TGT

Social climber
So Cal
Feb 7, 2013 - 08:58pm PT
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?
adatesman

climber
philadelphia, pa
Topic Author's Reply - Feb 7, 2013 - 09:01pm PT
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...





adatesman

climber
philadelphia, pa
Topic Author's Reply - Feb 7, 2013 - 09:07pm PT
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....
hillrat

Trad climber
reno, nv
Feb 7, 2013 - 09:11pm PT
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?
TGT

Social climber
So Cal
Feb 7, 2013 - 09:14pm PT
I think this is what ya got

http://books.google.com/books?id=s1EVyLn5GT0C&pg=PA53&lpg=PA53&dq=hydraulic+servo+cylinder+valve+combination&source=bl&ots=wfJgAk13_c&sig=IjP3ZFDvGCPoTQhVwniJzJ7FiBE&hl=en&sa=X&ei=Dl8UUcpKpv2JAvSygIgG&ved=0CDkQ6AEwAg#v=onepage&q=hydraulic%20servo%20cylinder%20valve%20combination&f=false

Don't think this helps much though, but if the piston is bypassing too much you might not have enough pressure to shift the valve back to neutral.
hillrat

Trad climber
reno, nv
Feb 7, 2013 - 09:15pm PT
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.
adatesman

climber
philadelphia, pa
Topic Author's Reply - Feb 7, 2013 - 09:22pm PT
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.
adatesman

climber
philadelphia, pa
Topic Author's Reply - Feb 7, 2013 - 09:30pm PT
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?
adatesman

climber
philadelphia, pa
Topic Author's Reply - Feb 7, 2013 - 09:39pm PT
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).
adatesman

climber
philadelphia, pa
Topic Author's Reply - Feb 7, 2013 - 09:41pm PT
Ok Guys, calling it a night here. I've got the little one in the morning, so gotta turn in.

Thanks again!
-aric.
hillrat

Trad climber
reno, nv
Feb 7, 2013 - 10:34pm PT
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,
photo not found
Missing photo ID#288597
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.
adatesman

climber
philadelphia, pa
Topic Author's Reply - Feb 8, 2013 - 11:56am PT
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.
adatesman

climber
philadelphia, pa
Topic Author's Reply - Feb 8, 2013 - 12:05pm PT
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.
hillrat

Trad climber
reno, nv
Feb 8, 2013 - 12:19pm PT
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.
hillrat

Trad climber
reno, nv
Feb 8, 2013 - 12:24pm PT
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.
adatesman

climber
philadelphia, pa
Topic Author's Reply - Feb 8, 2013 - 01:22pm PT
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....
hillrat

Trad climber
reno, nv
Feb 8, 2013 - 01:45pm PT
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.
adatesman

climber
philadelphia, pa
Topic Author's Reply - Feb 8, 2013 - 01:46pm PT
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.
GhoulweJ

Trad climber
El Dorado Hills, CA
Feb 8, 2013 - 02:01pm PT
Just get a good used cylinder/valve.

Unless your time has no value then keep F'ing the dog.

http://www.myerswardtractor.com/
GhoulweJ

Trad climber
El Dorado Hills, CA
Feb 8, 2013 - 02:09pm PT
I see you're in PA.

These guys do a great job at used tractor parts and they're closer to you.

http://www.pleasanthillfarmsupply.com/
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