Problem with Lift Tilt Dump...

[SnowRidge]

I think your lift/tilt valve assembly is sticking in bypass.

 

[J_J]

I believe the PT steering assembly has a priority valve that allows steering only when you turn the wheel. When you release the wheel, the steering valve is supposed to center, and therefore, the lift/tilt circuit gets the pressure and volume from the steering and lift pump. If the steering is working, then that part of the steering assembly is OK. Just a small amount of steering will interrupt the lift and tilt. As the steering wheel comes back to center, the priority valve shifts automatically to allow all flow to the lift and tilt. If the steering wheel is sticking anywhere other than center, lift/tilt will not move. If your relief valve is not working, it may stall your engine, or break something or burst a hose. If the relief is relieving all the time, you should not have very much steering or lift/tilt. Yes, you can take the relief valves apart, and clean them, but you really need a gage to adjust the pressure. A test gage in the right place would have already given you the answer. For instance, if the gage is installed at the input of the steering assembly, and you are turning, you would see presssure based on the amount of force required to turn. . If no steering, and the lift/tilt circuit is lifting max load, the gage would show max pressure, and when you stop lifting, no work is being done, the pressure decreases because the fluid now goes back to the steering valve or tank. Your load checks would hold the load.

 

[woodlandfarms]

JJ... Interesting stuff.

The problem is that I am completely dead in the water. Like I am getting no juice to either the Steering or lift and tilt.

I pulled the pressure relief valve and the pump is pumping. Because it is intermittent I think putting a guage in the system is just going to be more frustration... I would need a series of guages and then I would be driving a guage an not a tractor...

Anyway... Will talk to Terry as this 1850 does not match any schematics I have yet to see.

Carl

 

[J_J]

JJ... Interesting stuff.

The problem is that I am completely dead in the water. Like I am getting no juice to either the Steering or lift and tilt.

I pulled the pressure relief valve and the pump is pumping. Because it is intermittent I think putting a guage in the system is just going to be more frustration... I would need a series of guages and then I would be driving a guage an not a tractor...

Anyway... Will talk to Terry as this 1850 does not match any schematics I have yet to see.

Carl

The gage thing is just a quick disconnect in each of the three circuits. the one pressure gage is plugged into the circuit you are trouble shooting.

If you take it to a shop, the first thing they are going to do is put a gage in the circuit with a flow meter.

 

[SnowRidge]

I believe the PT steering assembly has a priority valve that allows steering only when you turn the wheel. When you release the wheel, the steering valve is supposed to center, and therefore, the lift/tilt circuit gets the pressure and volume from the steering and lift pump. If the steering is working, then that part of the steering assembly is OK. Just a small amount of steering will interrupt the lift and tilt. As the steering wheel comes back to center, the priority valve shifts automatically to allow all flow to the lift and tilt............

I was curious about your theory, J_J, so I experimented a bit with my PT-425 today. I was moving my 20 foot trailer around using a ball mount on QA adapter plate. I could not at any point disable the lift by turning the wheel. I was able to raise and lower the trailer tongue with the lift arms at will, all while steadily cranking the steering wheel either right or left.

The theory does not appear to hold up on the PT-425.

 

[ponytug]

It's true for the 1445. Perhaps it is a red thing.

Cranking the steering to the limit trips some relief and preempts lift/curl/QA. Trying to use them drops the cylinders.

It occurs to me that a malfunction in the steering assembly, in lieu of the pump issue, would also cause the same symptom, but Woodlandfarms would be noticing the load. (You would hear some hydraulic noise from either the steering or the relief valve or both.)

All the best,

Peter

I was curious about your theory, J_J, so I experimented a bit with my PT-425 today. I was moving my 20 foot trailer around using a ball mount on QA adapter plate. I could not at any point disable the lift by turning the wheel. I was able to raise and lower the trailer tongue with the lift arms at will, all while steadily cranking the steering wheel either right or left.

The theory does not appear to hold up on the PT-425.

 

[J_J]

I was curious about your theory, J_J, so I experimented a bit with my PT-425 today. I was moving my 20 foot trailer around using a ball mount on QA adapter plate. I could not at any point disable the lift by turning the wheel. I was able to raise and lower the trailer tongue with the lift arms at will, all while steadily cranking the steering wheel either right or left.

The theory does not appear to hold up on the PT-425.

Let me ask you this? How many pumps do you have, and does a single pump provide hydraulic fluid to the steering circuit?

 

[SnowRidge]

Let me ask you this? How many pumps do you have, and does a single pump provide hydraulic fluid to the steering circuit?

Three, not counting the charge pump inside the drive pump case.

I think so, but the manual does not have a proper hydraulic schematic. It also covers multiple versions without naming or describing them. In short, it is pretty useless.

 

[toy]

I was curious about your theory, J_J, so I experimented a bit with my PT-425 today. I was moving my 20 foot trailer around using a ball mount on QA adapter plate. I could not at any point disable the lift by turning the wheel. I was able to raise and lower the trailer tongue with the lift arms at will, all while steadily cranking the steering wheel either right or left.

The theory does not appear to hold up on the PT-425.

It is when the jacks on the steering is fully extended on one side and the opposite side is fully retracted and you continue to try to cut it steeper that it affects the lift and dump. With the bucket loaded and you do this it may not completely stop it from raising but on mine you can tell definitely that it slows it down lifting a load, and if I remember correctly it completely stopped the lift a few times. JJ is right about putting a gauge on it to see what your pressures are and totally forget doing any adjusting the pressure without a pressure gauge it is dangerous to do that and if you do get a gauge and put on your machine remember we have a open center system[ pt 425] and unless you stall the function you are checking you can't get an accurate reading on the gauge. If you have a broke spring in the relief valve it will cause the loss of function in the circuit and in that case you might not hear the shishing sound of the relief valve bypassing. The relief valve is preset at the factory.

 

[woodlandfarms]

talked to Terry. More than likely a bad relief valve. I have the pressure guage and will play with it, but it is either going to have to fail or get replaced by luck for me to really find the intermittent issue.

I pulled the relief valve but it has continued to act up so I think it is the valve itself.

I need some education on how a relief valve works. going to post that request in Hydraulics if anyone wants to weigh in...