Hydraulic steering help

[ParkerFly]

If any of you all are familiar with tractor pulling, I have one of the sleds that the tractor pulls. It has a set of wheels on the front that lower to pick the pan up and steer to drive the sled around when its not being pulled. This steering setup does not use a tie rod, but an individual cylinder on each wheel and the line going to them runs through a gear type flow divider to keep the wheels in sync. My sled has a cab off of a Case 1660 combine, and the steering valve is the one that was already in the cab. I just put a priority valve in my system to feed the steering valve 4 gpm at 1500 psi.
The problem I have is that when I'm driving the sled, if I'm on smooth hard ground the steering works great. If I am on a soft track, or if a tire hits a dirt clod or something when I'm backing up it will kick the tires out of line. It pushes the fluid right out of the cylinder and the tires will flop around and this is with me holding the steering wheel still. I know this setup works, almost every other sled out there uses one just like this. The only thing I'm not sure of is if they are using a different steering valve? I can't understand why the pressure could be just pushed out of the cylinder like that.
Can anyone give me ideas what may be wrong? Going to a tie rod setup would mean redoing everything I've already done, and I'm not convinced it would solve the problem...I think it would keep the tires in line but still kick them around whichever direction it wanted. I attached a couple of pictures to maybe help people have an idea of what my setup is. Thanks.

Justin

 

[Tx Jim]

Have you ever tried converting the double acting cyl. into single acting such as the parts schematic?

 

[ParkerFly]

I'm a little slow sometimes with them, if you can explain to me what the advantage would be with changing the cylinder over to single acting? Thanks.

 

[davedj1]

I'm no expert but I think what he is saying is "one would pull and one would push" keeping them working together.

 

[Leejohn]

If it was me, I would check and make sure the hoses are the same in lenght and I.D. Then double check the fitting I.D. and make sure they are the same. After that I would bleed the system real good. It sound like to me you have air in the system or picking up air from some where. Then go for the steering valve. Do you know the mfg of the steering valve?

 

[Tx Jim]

I'm no expert but I think what he is saying is "one would pull and one would push" keeping them working together.

That's basically correct. The parts photo I posted came from one JD tractor model that utilizes that type steering

 

[bandaidmd]

I cant seem to find you a link for it but what would work is called a lock valve, sometimes there mounted on a hyd toplink and they wont let the cyl move until full pressure is applied.
I think this is the one but a call to them might help.
http://www.surpluscenter.com/Hydrau...NCE-RD1650-PILOT-OP-CHECK-VALVE-9-8407-50.axd

http://baileynet.com/hydraulics/check_lock_needle_and_flow_control_valves

 

[bandaidmd]

That's basically correct. The parts photo I posted came from one JD tractor model that utilizes that type steering

something up in the valve is what prevents the wheels from moving independently.
My snowplow works pretty much the same way, it has single acting cyls on each side and all the "magic" happens in the valve body in this case via electric valves. It moves when the button is pushed and hydraulically locks when you remove the current.

 

[Tx Jim]

I agree that the steering control valve has some bearing on the correct operation of the steerable wheels.

 

[Xfaxman]

Have you ever tried converting the double acting cyl. into single acting such as the parts schematic?

I'm no expert but I think what he is saying is "one would pull and one would push" keeping them working together.

That's basically correct. The parts photo I posted came from one JD tractor model that utilizes that type steering

That would work if the sled had a tie rod, like the JD tractor has, but it doesn't, so it won't work.