Hydraulic Power steering problem

[Prankstar]

I'm having a weird problem with my New Holland 1530 compact tractor. The power steering cylinder/ram is bending shafts like crazy. I'm on the 3rd bent shaft. When I'm steering all the way to the left and hit the lock the shaft wants to keep pushing out of the cylinder and ultimately bends the shaft as if it were hollow. I did an inline (in series) power steering pressure test and the pressure is jumping real high when the steering gets to the locks. I saw the gauge staying fairly steady at 1400 psi and below while turning the wheel and then jump upwards of over 4000 psi when it's on the lock. I back off immediately as it scares me to see that much pressure. I'm not sure if it would go any higher.
That seems like excessive pressure to me so I took the relief valve out of the steering motor under the steering column to inspect it. It's a very simple valve and doesn't appear to be sticking. I could be wrong though. I did see some slight wear on it but not much.
I'm assuming that this pressure is way to high, and it is just a simple system that consists of a steering motor (I don't understand this part very much)that connects directly to the steering wheel, a pump, and a steering cylinder/ram.
Any help would be greatly appreciated.

 

[beenthere]

Duplicate post in the New Holland board.

 

[J_J]

If you saw that kind of pressure, the relief for the steering must not be working. Did you check it or just observe the pressure?

 

[AKKAMAAN]

Post that "says more than 1000 words-picture" of the cylinder when it is in the position when it bends including linkage etc...fully out..??

Is this a cylinder with double rods, one in each end of cylinder??

3rd bent rod.....trouble shoot outside the hydraulics....sounds like you have a mechanical problem with steering linkage out of sync and alignment....

 

[Prankstar]

How can I check the relief valve? I took it out of the steering motor but didn't see much wrong with it and wasn't really sure what to look for.

The tractor does have a front end loader, and a 3 pt hitch in the rear, mid pto, rear pto.

The power steering has its own system on this tractor. I don't believe that it controls the other hydaulics. There is a hydraulic pump on the side of the engine, but there is a power steering pump mounted perpindicular on it and I believe it just spins a gear off of it for the power sterring pump. I don't see a relief valve in the p/s pump. The relief valve is located in the steering motor that is mounted under the dash and the steering wheel column mounts directly to it. The only other parts to the system are hydraulic lines and the Cylinder. BTW the cylinder is fixed on one end (and Closed), to the center of the tractor and the rod only comes out one side of the cylinder.

The Manual states that the pressure should be around 1300-1500 psi. But it doesn't say what it might jump up to when the steering hits the locks. The locks are just adjustable bolts on the wheel hubs that hit the front axle when all the way turned.

My feeling is that the steering cylinder rod is pushing out at normal pressure, then the lock hit the axle and the pressure ramps up and the rod still has some travel and it pushes on it so hard that bends the rod. This occurs while turning to the left. When turning to the right everything is ok because the rod is retracting into the cylinder.

I will doublecheck the steering linkage and alignment but it appeared to be good at first inspection.

Why would the pressure reach 4000psi?

 

[V1Rotate]

Check to see that the front wheels are turning equal amounts both to the left and to the right when the steering wheel is turned lock to lock, (carefully so you don't bend another cylinder). It might be possible that the steering lock nut that limits the travel when you turn to the left may have come out of adjustment, causing the steering cylinder to hit the stop prematurely and thus bending the rod.

 

[Jbrink64]

The relief is the problem. You should never see pressures above 1500psi. The passage that leads to the relief valve may be plugged, or, the valve is sticking in it's bore, or, the spring is set too tight.

 

[J_J]

Install a gage in the PS hose and turn the wheel to lock and see if the pressure goes above 1500.

Just about all hyd systems have a relief valve somewhere to protect the system. If the fluid has nowhere to go, and the cyl walls are thick, then the pump will try and pump that fluid against the resistance, which is the rod at the end of the stroke. If that point is an immovable object, then the rod will probably bend or a hose will burst.

The relief is probably on the pump or valve.

I just saw that you had taken the relief valve off and saw nothing wrong. Were all the parts there? Was the spring broken? Did the seat look OK? Was there any trash in the orifice.


Do you have a hyd schematic for your tractor?

 

[Prankstar]

Ok. Thanks for confirming that the pressure shouldn't go over 1500psi.

I will take the relief valve out again tomorrow. I'm probabaly going to end up rebuilding the steering motor also. Hopefully I can get some pictures of it on here for show and tell.

The other awesome problem is that New Holland doesn't sell a replacement relief valve.

 

[J_J]

Does your steering wheel valve look anything like this? My Power-Trac uses a steering valve on the steering like this. The valve operates at a higher pressure. 2500 to 3000 psi.