Anyone familiar with early hydraulic steering systems?

Hi all,
This is slightly off-topic, but I need to fix the power steering on an
old JCB backhoe loader, and I thought there might be an expert here who
could offer some suggestions. I think the design of this power steering
system dates back a long way. The machine has a regular tractor steering
box, but in between the steering link and the crank which turns the
wheels is a hydraulic ram. One end of the ram is attached to the
chassis, the other end to the steering crank (i.e., the crank at the top
of the king pin) and the link from the steering box attaches to a large
pin on the side of the ram. It appears that when a force is applied to
this pin, it operates a pair of spool valves inside the body of the ram.
A separate pump operates the steering from the pump which drives the
backhoe and loader. I think - but I'm not sure - that the steering pump
continuously forces oil through a small orifice and the spool valves
simply divert a bit of oil into the ram when the steering wheel is
turned. This avoids needing a pressure relief valve I guess. The
steering ram/valve unit is marked "Hydrosteer 33/64. Patents Pending. VC
140017." The steering doesn't work, but the ram isn't leaking or
damaged, and the spool valves seem to move freely enough. I wonder if it
is some kind of adjustment problem. I know the chances are slim, but is
anyone here familiar with this kind of hydraulic steering and what the
common problems are?
Best wishes,
Chris
Reply to
Christopher Tidy
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I have a 1962 Fordson Major tractor with backhoe and loader that uses the Hydrosteer ram system. Have had two cylinders apart and got one working. Other one has major damage and missing parts. I have not found any information except exploded parts diagram and basic disassembly and reassembly. Your understanding agrees with my findings. Oil flows freely through the open valve(s) until moved by steering force. If no pressure and steering aid is evident, the valve is not being closed off, the internal cylinder seals are leaking, or the pump is defective. There may be a relief valve in the pump which must be closed except to relieve excessive pressure build up. Don Young
Reply to
Don Young
Thanks very much for the advice. I was doubtful I'd find anyone with experience of these, but RCM comes to my aid again! I have a spare cylinder, too. One was originally fitted to the machine, but split because an oversize tyre had rubbed against the side for many years and worn away the wall. This cylinder worked fine until it split. Then I got a spare cylinder from a friend and fitted it, but it didn't work, so I assumed that the problem is with the cylinder, but it could be that two problems have developed at once.
Peering into the ports, the valve spools look slightly different in the two cylinders. One has a hole through the spool visible, whereas the other doesn't. It may just be that the spool is free to rotate, so that the hole isn't always visible, but I'm not sure.
There's no sign of steering force at all, and it's pretty well impossible to steer this machine without the power assistance (it's about 7 tons). However, with the front wheels lifted off the ground, it is possible to turn the wheels, even with the engine switched off if I recall correctly. Do you think a defective piston seal is likely? It fits some of the symptoms, but I'm surprised I can't see any steering force at all. These units don't need bleeding when you fit them, do they? I assume the air finds its way out through the reservoir naturally.
By the way, are there any exploded parts diagrams available online?
Many thanks for the help.
Chris
Reply to
Christopher Tidy
Two likely suspects here. One is the pump may not be pumping (for what ever reason). The other is that the seals may be out on the piston of the cylinder. Either would prevent it from working.
Wayne Cook Shamrock, TX
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Reply to
Wayne Cook
These were common as dirt on a variety of trucks & tractors, Ford, Austin, Leyland etc as well as DB, Nuffield, Ford tractors. The majority of problems lie generally in the pump, rather than the ram.
I can send scans of the o/h instructions etc at the WE if you like, a trifle busy at present..
Tom
Reply to
Tom
Read what you just wrote. "It was fine until the cylinder split and when I fitted another (not new) cylinder it wouldn't work" Kinda points to the problem to me.
Reply to
Clif Holland
There are several "Old tractor" web sites, discussion boards, etc. which can be very useful for this sort of question (and for finding parts, if parts are needed). Here is one, there are others.
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My power steering problem is a bit more basic - the end snapped off the ram, and I have not yet been able to get the tapered pin out of the other end of the cylinder to get it out and fix it. The local tractor dealer says they normally burn those pins out, and notes that you need a fire extinguisher handy, since all the oil that collects in that area on my type of tractor tends to light up when the pin is burned out with the cutting torch. I'm trying to avoid that, and it costs too much to have the tractor hauled in for them to work on it, but I'm disproving all sorts of claims for miracle fluids from Kroil, PB blaster, etc...
Reply to
Ecnerwal
Here's a trick I learned to remove ball joints. It may work for you. Ball joints with a tapered pin that is drawn tight into a socket are supposed to be removable with a "pickle fork". When this doesn't work hitting the side of eye where the tapered pin is deforms the eye and the taper lets go. Now, I've only done this on cars. And only when the other methods didn't work. But it has worked every time. If your tractor is set up the same it may work for you. It may also help to heat the area first, being careful about fire of course. ERS
Reply to
Eric R Snow
IIRC you need to raise the front end and crank the steering fron full lest to full right and back several times with the engine running to get all air out. The valve bleeds itself, but the cyl doesn't.
Reply to
nospam.clare.nce
My gut reaction is that there's nothing major wrong with the system. An airlock seems a possible cause, but I've never had problems with airlocks on the machine's other hydraulic systems. I thought larger, powered hydraulic systems didn't usually need bleeding. Now this digger doesn't get used often, and it must be a year or so since I fitted the replacement cylinder. When I replaced the cylinder I did lift the front end and crank the steering from side to side. It didn't work. So I topped up the oil level and I was sure I remembered the steering working, but now I'm not so sure. Next time I used the machine it blew a big hose and lost a lot of oil. I fitted a new hose, topped up the oil, and then noticed the steering wasn't working. The pipe which leads from the reservoir to the steering pump is weird. It goes up in a loop, so that the centre of the pipe is higher than either the reservoir outlet or the pump. I thought this must be the way it was designed, but now I have my doubts. Maybe I should get a shorter hose made so that it is horizontal? An airlock seems a likely culprit now. I would have expected dodgy piston seals to reduce the steering force, but not make it disappear. I'll have another look at the machine this weekend.
Many thanks for all the suggestions.
Chris
Reply to
Christopher Tidy
I think I might (hopefully) be near to solving the problem now, but if you do get chance to scan the diagrams that would be superb. The system is a mystery to me at the moment so it would be great to have some pictures showing how it works.
Best wishes,
Chris
Reply to
Christopher Tidy
If you can get to both sides of the boss that tapered pin is in here is something you can try. Grab two LARGE hammers. Put one on each side of the boss and while holding one hammer tight to the boss give it a GOOD whack with the other hammer. What it does is slightly deform the pin boss for an instant and breaks the pin free. The reason for two hammers is to use the weight of one to offset the force the moving hammer puts through the part. This method works great on ball joints and tie rod ends on most vehicles and is MUCH faster than a pickle fork.
Reply to
Steve W.
>
>> >> >> > This is slightly off-topic, but I need to fix the power steering on >an >> > old JCB backhoe loader, and I thought there might be an expert here >who >> > could offer some suggestions. >> >> There are several "Old tractor" web sites, discussion boards, etc. >which >> can be very useful for this sort of question (and for finding parts, >if >> parts are needed). Here is one, there are others. >> >>
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>> My power steering problem is a bit more basic - the end snapped off >the >> ram, and I have not yet been able to get the tapered pin out of the >> other end of the cylinder to get it out and fix it. The local tractor >> dealer says they normally burn those pins out, and notes that you need >a >> fire extinguisher handy, since all the oil that collects in that area >on >> my type of tractor tends to light up when the pin is burned out with >the >> cutting torch. I'm trying to avoid that, and it costs too much to have >> the tractor hauled in for them to work on it, but I'm disproving all >> sorts of claims for miracle fluids from Kroil, PB blaster, etc... >> >> -- >> Cats, coffee, chocolate...vices to live by >> > >If you can get to both sides of the boss that tapered pin is in here is >something you can try. Grab two LARGE hammers. Put one on each side of >the boss and while holding one hammer tight to the boss give it a GOOD >whack with the other hammer. What it does is slightly deform the pin >boss for an instant and breaks the pin free. The reason for two hammers >is to use the weight of one to offset the force the moving hammer puts >through the part. This method works great on ball joints and tie rod >ends on most vehicles and is MUCH faster than a pickle fork. > > > >
Reply to
Eric R Snow
I had a look at the hose today. The loop isn't quite as extreme as I remembered, and couldn't be reduced much by getting a shorter hose. I still think an airlock is a strong possibility, though. This is where I'll start my investigation this weekend.
Many thanks for the help.
Chris
Reply to
Christopher Tidy
If you can see inside the reservoir just check if oil flow is evident when the pump is operating and there is no force on the booster valves. There should be free flow through the booster when the valves are centralized. You might check the booster for free flow to the outlet port by using an air line at the inlet high pressure port, then for reduced flow and some piston force when the valve is shifted by applying steering effort. That should help localize the problem. Don Young
Reply to
Don Young
Don't run the pump much if there is no oil flow. Take the outlet hose off if you need to be sure. Don Young
Reply to
Don Young
Unfortunately I can't see inside the reservoir - the chassis is made from hollow steel sections and these form the reservoir.
Chris
Reply to
Christopher Tidy
I took the hose off when the engine wasn't running and a fair amount of oil dripped out. A while back I disconnected the hose and turned to engine over with the starter motor to check for flow. I'll do this again.
Thanks for the help.
Chris
Reply to
Christopher Tidy
Could you remove the high pressure hose from the cylinder or the low pressure return hose from the reservoir and stick the end back into the reservoir filler? Or maybe just into a clean bucket? Note that a gear pump works okay at slow speeds but a vane pump generally does not. A simple pump tester is a high pressure valve with a gage between the valve and the pump. Just throttle down the flow and see if the pressure builds up okay. Remember this system is normally free flow through the booster and pressure only builds up when the valves are shifted to divert flow into the cylinder. Don Young
Reply to
Don Young
Is this an integral valve unit, or does it have a separate "tower" and cyl? Fron William Crouse's automotive Mechanics text - In the linkage-type power steering gear the power cyl is not part of the steering gear. Instead the booster cyl is connected to the steering linkage. In addition, the valve assy is included in the linkage, either as a separate unit or integrally with the cyl. In operation the gear works exactly the same as mechanical steering, but the end of the pitman arm is not connected directly to the linkage. Instead, it connects to the valve assy. When the pitman arm moves, it actuates the valve assy which directs oil to the booster cyl where it is applied to one side or the other of the piston. The cvalve assembly works very much like the valve in an inline power steering unit - (early saginaw)
In straight ahead operation the spool is centered by one or more centering springs, and the oil from the pump is applied evenly to both sides of the cyl, cauasing a straight ahead "dead spot". When a turn is made, the pitman arm pushes the spool off center, allowing oil to flow into only one side of the cyl, and allowing the other side to vent back, through the valve, to the pump reservoir.
The integral unit (tower and cyl combined) is very much like a rack and pinion power steering unit, without the pinion.
Reply to
nospam.clare.nce

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