No power steering on a Terramite

[the old grind]

cstamm81, I questioned the hose(s) earlier but still have some doubt, esp if you've fully inspected them. (auto PS experience..) If either had ballooned/blocked there should be some pressure in one direction or the other(?) but if your cylinder moves freely unloaded I doubt it would be too high without being connected (weighted?) or at the end of stroke. It actuates by flow, of course, but some resistance may(?) help you interpret the tests.

Is there any reason S-box pressure output wouldn't be the same with the engine running or not, since the cylinder would be doing the same work either way to turn the wheels??? Whether the box is working would then only be obvious by effort/feedback at the wheel. Either you're getting 'boost' or not. If we can be sure the adapter plate is supplying adequate flow/pressure it would seem to point to the box as the problem. (Oh man, .. do I hope not ...)

I'll have to reread whether this issue just popped up or the T-M came this way. Could moisture/rust have stuck something delicate inside the box's control valving while stored/parked and stiffening/locking-up something? I had water collecting in my column without a center-button on the s-wheel. (doh!) Call me lucky that it hadn't gone inside & froze.

I'm hoping I can help out here without being a pest about it, but IMO us T-M guys could use some team work to get a handle on our steering issues. btw: I hope TerramitConnecticut is tuning in by now. Not sure he's up & running yet ...

 

[wdchyd]

Why when I have the engine off does the turning of the steering wheel pump so much fluid through the lines? I am thinking as I turn the steering wheel either direction it is just working as a diverting valve for the pressure supplied by the trans. But this wouldn't explain why there is pressure with the engine off.

internally in the steering unit there is a rotary valve and a geroler set (similar to a hyd motor).....when steering the geroler section acts like a manual pump with the rotary valve adding pressure to assist in the movement of hyd oil going to the steering cyl, this keeps the steering under you control and not oversteering acting proportional

when the engine is turned off then the geroler set is still "manually" pumping the hyd oil (without help from the hydrostat pump source), this condition is helpful when the engine goes into a stall you still have some steering......with the steering unit developing some steering flow this may confirm there is nothing wrong with the steering unit but rather the flow source (hydrostat)

internally in the hydrostat pump there is a geroler section on that rear cover that incorporates the extra pump for power steering....many times this section of pump is used for charge pressure for the traction loop (main piston pump to wheel motors).....they are probably using the same flow for both

if you're not getting proper flow/pressure out of that port then the next project would be to get the pump out and do some exploring

is there another pump mounted piggy-back on that main pump .....Pix..??

 

[the old grind]

Not speaking for cstamm81, but the 'Main power circuit' flow chart is shown on p 2.12 of the man. IIRC its one that was attached earlier but T-M's site abruptly went offline within the last wk or so & I'm digging for the PDF I printed mine from, a few computers/HDs ago. This popped up recently but doesn't explain a web shutdown, tho' it may portend an update/redo of the site ....New Terramite Owner Has Plans to Revive and Grow the Small Equipment Manufacturer

There is a gear pump at the tail end of things, but the flow chart shows it powering only the loader valve and digging/outrigger spool stack. Up front there's a 'backplate assy' (w/piston pump? ... it's between the HST and that 'adapter plate') that routes to the drive's torque-motor alone. There's a dedicated line shown from the HST to the s-box. At first look it appears the HST is getting its charge pressure independent of steering flow or any shared source/connection.

Many thanks to wdchyd for contributing his expertise. :thumbsup:

btw: I found/downloaded T5C's manual from here: http://www.terramite.co.za/T5CPartsManual.pdf It shows a bit of both steering setups vs my older copy but is mostly a parts guide. Mentally connecting the pages/pics leaves room for some confusion, but mebbe that's just me .... :mur:

 

[wdchyd]

Yep, looks like they are using charge pressure to power the steering

 

[J_J]

If you put your gage in a tee at the input to the steering valve, what pressure do you read?

Run the engine abut mid rpm, and you should get around 350 to 1000 psi, the steering.

The charge pressure on my pump is about 350 to about 450 psi.

That pump is very similar to my Eaton hydrostatic VSP pump, but my steering valve uses a separate pump for the pressure and it is about 3000 psi.

I am also thinking the pressure for the charge pump is stamped on the relief valve using a code. IE, 022 = 220 psi, etc

A flow and pressure test will will tell you more.

These are the fluids recommended for Eaton VSP pumps.

Specific types of fluid that meet these requirements are:
• Premium quality, industrial anti-wear type hydraulic fluid
• Engine crankcase oil — SAE 10w, SAE 20w-20, SAE 30
• Automatic transmission oil
• Hydraulic transmission oil
• Synthetic fire resistant fluid — Quintolubric, Cosmolubric, or equivalent

Note: If the natural color of the fluid has become black or milky it is possible that an overheating or water contamination problem exists.
Take level readings when fluid is cold.

Some people will look at this and say that is just wrong, but this if from the manufacturer. My VSP has been using motor oil since the90's.

 

[J_J]

Operation of Eaton VSP and charge pump.

http://eatonsite.com/HydPLL/pdfs/E-PUPI-TM010-E.pdf

Page 12 also shows the bypass valve so you can tow the machine if broken.

Only recommended for short distances.

 

[cstamm81]

I spoke to TM today. The guy was quick to point the finger at the adapter plate, which is sandwiched between the hydrostat and the rear gear pump. He said I should have between 200 and 300 psi at the adapter plate port. It sounds like this is something that has been known to fail. It does not look too hard to remove, and I wondering if it is repairable. He did have the plate in stock at a little over $400. Pricy but if this will make the power steering work without any jury rigging it is probably worth it.

I am still surprised I have decent flow from that port, but I am going to get a short length of hose and tee in the gauge just to verify pressure. I guess the pump section of that adapter plate just got weak? I may even run a line off the loader valve to the steering box and just crack the valve to make sure the system works at that point.

wdchyd, thanks again for the explanations to these things. the old grind, I appreciate the input it has also been a big help. I just found out my T5 is a 1994 model, what year is yours? There HAS got to be a replacement for that steering box of yours...

 

[cstamm81]

Well, I believe wdchyd was right all along. I've got a whopping 20-40 psi at full throttle coming right off of the adapter plate port. SO, that is definitely the issue. I also ran a line from the front loader into the power steering just to make sure, and when I cracked the valve the steering as boosted.
So, I definitely need the adapter plate. Would anyone have a decent idea if there is something in there that is rebuildable? I am assuming there is some type of pump, impeller, rotors? TM wants 400 for the plate, and 1400 for the plate AND the hydro trans, whole assembly minus the rear pump.
I barely ran this tractor before ripping into it, but I did recognize it did not have quite as much speed in forward as my other TM. There is also a growl from the trans when getting off of the hydrostat pedal. Lastly it seems to coast after getting off the pedal, where my other T5C immediately comes to a stop. I am bringing this all up wondering if this is a sign of a hydro trans on it's way out as well.

 

[wdchyd]

Yea, the coasting is a sign the charge pressure is n/g (the same section that supplies pressure/flow to the steering)

Time to yank that pump, dissect it and post up close-up pix

the aux pump in the rear is not necessary to take apart, but it won't hurt to peek inside

I may have some used parts for that adapter plate.....I'll look 2moro at some used pumps kicking around.......you'd be into replacing the housing and geroler section if indeed the pump is worn

the rotation group (barrel, pistons and shoes) in the front section you'll wanna look real close at any wear......where the piston barrel rides on the valve plate you'll wanna look at that wear close too.....it may need lapping

pay attention to the cleanliness of the oil, sometimes contaminated oil will do this kind of damage without knowing it.....either way, you'll be doing a complete oil/filter change and rinse out the reservoir

 

[cstamm81]

So the replacement of the adapter plate should take care of the steering AND the coasting issue? Will this help with the speed in forward? The tractor seemed to have plenty of torque, as I loaded it up very steep ramps onto my trailer.

Are you suggesting yanking the whole assembly out; trans, adapter, gear pump in one? TM service told me 20 minute job to separate and replace just the adapter plate... maybe if you have done it before. Or, are the inspections you are suggesting just part of the adapter plate?

The other pieces you want me to inspect, is this going to be fairly straight forward or could I quickly have a nightmare on my hands? I am a pretty competent mechanic, rebuild engines etc but I do know I have my limits.

I would love to replace or repair everything, but spending around 2K (I am guessing) isn't really feeling great to me, on a tractor I only paid 3700 for. I hate to half a** things though, so if I could rebuild things while I am at this I am all for it.

As for the hydraulic system oil, previous owner just had it changed. Said he put in 10W-30, too bad as the manual calls for 15W-40 or straight 10W(?). Who knows what has been run through this thing it's entire life...