Problem with Lift Tilt Dump...

[woodlandfarms]

OK, this is a bizarre one. Got up this morning, started the tractor and went to disconnect one implement. Nothing worked. Wheels turned, PTO comes on, lift dump does not work. I wait a minute, restart and it works. OK, So I think ghost in the machine. Well, it did it again. Once it works it appears to work strong. So now I have a weird intermittent hydraulic issue and no idea what to look for.

Any ideas?

 

[Bob999]

Two possibilities come to mind:
1. A problem with the lift/tilt valve or linkage; or
2. a sticking relief valve in the lift/tilt circuit

 

[SnowRidge]

Two possibilities come to mind:
1. A problem with the lift/tilt valve or linkage; or
2. a sticking relief valve in the lift/tilt circuit

I ran those two scenarios through my head, too. I don't know why the relief valve would have been open in the first place, so I eliminated that one. I would have thought that a linkage problem would have been "feelable." Is that a word? You know what I mean. If there was something wrong with the linkage, I think you would feel it.

I have to admit, I don't know much about the big PTs. WoodlandFarms, how is that particular pump driven on your machine? Any chance something is slipping, and the pump isn't starting properly? Does it have its own coupling? Just guessing right now.

 

[woodlandfarms]

Linkage looks good. I mean I look under and things move like they are supposed to. And it is weird. It runs one moment then when I restart it is gone, then it starts. Problem is that there is NO hydraulic diagram for my particular PT. At least that I know of.

There are three pumps, wheels, pto, and steering lift. I have to double check but I think steering works when the lift does not... There is that charging circuit... Man. Call to Terry I guess. Nothing looks like it is leaking. I hit it with a hammer, nothing...

Darnit. My pickup blew up today. Not sure but I think I am cursed this weekend mechanically. Thank god our burn piles did not go out of control I guess...

 

[SnowRidge]

............. Thank god our burn piles did not go out of control I guess...

That last I guess bit instantly reminded me of the Man's Prayer: "I'm a man, but I can change, if I have to, I guess." I repeat it frequently, as a supplication to my wife.

If you don't know what I am talking about, you have missed one of the best shows ever on TV, in my opinion. Even my wife liked it.

 

[Bob999]

I think the 1845 and 1850 have the same basic hydraulic layout. The three pumps are stacked on the front of the motor. The drive connections are internal in the stack and I have never disassembled my 1845 so don't know if a drive connection could be the problem.

The steering is driven by the same pump as the lift tilt and if the steering works when lift tilt doesn't it woud suggest an intermittent blockage in a hose or fitting that is associated with lift tilt but not steering.

If none of the items driven by the pump for lift steering work the other possibility I can think of would be an intermittent blockage in the intake (supply) line for the lift/tilt pump. That would require some fairly large debris in the hydraulic reservoir!

 

[woodlandfarms]

Well, whatever is going on is systemic to the pump system for the steering and lift. My gut tells me that it has to do with the accumulator circuit...

Hmmmmm..... I wonder...... The thing I can't figure out is which pump runs the steering and lift.... The pump at the closest to the motor looks like it runs only the treddle. The second pump is steering. The third pump is PTO...

Grabbing the manual - AKA parts catalogue -

NOW I get it. OK, there are 3 pumps but only 2 pump assemblies. The PTO pump housing is also the housing for steering. I have had HUGE problems with small debris lodging itself in my PTO switch assembly, which is also the where the steering lift pump feeds through. I wonder if debris is lodged in the bypass control valve... Or it is sticking a bit for no good reason...

Well... At least a place to start... Time to get oily

Carl

 

[woodlandfarms]

I took apart the PTO Valve assembly (Again, probably the 10th time) and found nothing obstructing. Put it back together. Did the same thing. Smacked it with a hammer and it worked... So, I think I may have a sticky relief valve. I have no clue how those work, I guess I need to get them from Terry as they are set up at the factory...

Can anyone educate me on how these work. I assum there is a spring in there that when enough pressure is applied the valve "opens".

Its seems very, very, very restrictive. All of these valves have seemed very restrictive for a 18GPM system.

 

[Bob999]

Well, whatever is going on is systemic to the pump system for the steering and lift. My gut tells me that it has to do with the accumulator circuit...
Carl

I don't think so--I think the brake tender circuit--which the accumulator is a part of--is powered off the drive system (the variable displacement pump) See attachment.

As to reliev valves--they are adjustable spring pressure. I THINK all valves used by PT are externally adjustable by loosening a jam nut and then turning the adjustment to vary the spring pressure. You can remove the entire valve from the block it is mounted on without changing the setting to check that the port into the valve is not blocked.

Based on the information you have posted I think the most likely cause of your problem is foreign material somewhere in the lift/tilt/steering system.

 

[toy]

Woodlandfarms This probably isn't your problem but on the 425 if you have the machine cut to an extreme and when you start up the machine you have hold of the steering wheel with pressure to cut it farther that affects the lift and the dump. Did you have the machine fully articulated when this happened? It would be great if something that simple was your problem but as much problems as you have had with busting hoses and the such you probably aren't that lucky. When this occurance happens does the steering perform sluggishly. If a relief valve is stuck open it would cause the problem but you should be able to hear a shishing sound if that is the case. If the steering is ok at all times but the lift and dump isn't I would think that that would be a good sign concerning your pump. I hope you get it worked out soon.

 

[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...