Problem with Lift Tilt Dump...

[SnowRidge]

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..........

Yes, but that's a relief valve opening because the steering rams are at their limits, not a priority valve diverting flow because the steering wheel is being turned, as I understand J_J's theory.

 

[catsco]

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.

My PT-425 (2004, Kohler engine, fuel tank in steel lid) DOES disable steering/lift depending upon which is being used. While moving around, raising the bucket disables steering, and steering disables lift.

Lowering the bucket has no effect on steering, and steering has no effect on lowering the bucket.

Probably one of the many variations of PT design theory!

Regards,
Mark H.

 

[J_J]

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...

Carl,

A relief valve is a simple device with a seat , a shaft that sits on the seat, and a spring, plus an adjusting nut. A strong spring holds the shaft on the seat until the pressure builds up enough to raise the plug and release the pressure. Some relief valves are fixed at a certain pressure, and others are adjustable. The set range may be as low as 500 psi to 3000 psi. The relief should be set to relieve the pressure below the maximum pressure of your hydraulic components.

 

[J_J]

I don't know what valve you have on your particular PT, but I think it is a safety thing to have a priority valve. It could be one of several valves, poppet valve, shuttle valve, slide valve. I do know that my lift operation stops when I turn. You can test this by putting a pressure gage at the input to the joystick valve. At the no turn position, you should have high pressure while trying to lift a heavy load. Now, while trying to lift, turn the steering wheel a little and check the pressure, and turn the steering to the limits, and check the pressure. You will have very little pressure unless you are doing work. If you are lifting a light load, you will have med pressure. You will see max pressure when lifting max load. Now if the gage were at the input to the steering circuit, and you turn the steering to the limit, the relief valve would operate, and show you the relief pressure. You would also be able to hear the relief valve bypassing.

An analogy might be electrical circuits, You can only guess what is happening in a circuit unless you put a meter in the circuit to give expected results, or not. If the test are not correct, you then start the process of trouble shooting, but you need that meter.

In general you have to know how the system works.

 

[J_J]

My PT-425 (2004, Kohler engine, fuel tank in steel lid) DOES disable steering/lift depending upon which is being used. While moving around, raising the bucket disables steering, and steering disables lift.

Lowering the bucket has no effect on steering, and steering has no effect on lowering the bucket.

Probably one of the many variations of PT design theory!

Regards,
Mark H.

Are you sure you disable steering while lifting? Doesn't sound logical. I believe steering always has priority,

What about raising a load while steering. You can always lower a load even with the pump off. In lowering, you are only opening a valve to release fluid back to tank.

 

[J_J]

Just to clear up what I said above. When lowering a load with pump running, the load is lowered by gravity, or a little pump pressure. If you continue to lower past the ground level, IE, raising the front wheels off the ground, then you are using high pressure to accomplish this.

 

[SnowRidge]

My PT-425 (2004, Kohler engine, fuel tank in steel lid) DOES disable steering/lift depending upon which is being used. While moving around, raising the bucket disables steering, and steering disables lift.

Lowering the bucket has no effect on steering, and steering has no effect on lowering the bucket.

Probably one of the many variations of PT design theory!

Regards,
Mark H.

Interesting. In well over four hundred hours of operation, I have never expererienced any interaction between lift/tilt and steering.

 

[woodlandfarms]

I really need a hydraulic schematic. My PT is so different than what you guys must have. these are moments when I want to ring Terry's neck.

Terry and I had a long talk. turns out that it is not the relief valve at the PTO block. The giveaway is that my brakes are working. We now suspect a blocked charging circuit. I have to pull it out, and put a guage on the whole system per JJ's recommendation. I will try to document my activities.

Apparently at the bottom of the charging block is a plug. Under the plug is another plug with a hole in it. This hole may be plugged up.

Carl

 

[MossRoad]

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...

Nice to see you are risking the Kubota's life by the fire and not your Power Trac's!

 

[MossRoad]

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.

Our PT425 will sometimes not lift if I have the wheel all the way to one side. If I just let go of the wheel, it then lifts, but holding it to one side, it will not.

 

[J_J]

I don't know what valve you have on your particular PT, but I think it is a safety thing to have a priority valve. It could be one of several valves, poppet valve, shuttle valve, slide valve. I do know that my lift operation stops when I turn. You can test this by putting a pressure gage at the input to the joystick valve. At the no turn position, you should have high pressure while trying to lift a heavy load. Now, while trying to lift, turn the steering wheel a little and check the pressure, and turn the steering to the limits, and check the pressure. You will have very little pressure unless you are doing work. If you are lifting a light load, you will have med pressure. You will see max pressure when lifting max load. Now if the gage were at the input to the steering circuit, and you turn the steering to the limit, the relief valve would operate, and show you the relief pressure. You would also be able to hear the relief valve bypassing.

An analogy might be electrical circuits, You can only guess what is happening in a circuit unless you put a meter in the circuit to give expected results, or not. If the test are not correct, you then start the process of trouble shooting, but you need that meter.

In general you have to know how the system works.

Today, I cranked up the old 1445, because I plan to use it to unload some shidsteer stuff. I also purchased a Case 1845c ,60 hp skid steer, with bucket, tree digger, 3 set of forks, bush hog, and disk harrow., plus grouser tracks that fit over the wheels. With an adapter I should be able to interchange attachments. It also uses multi-grade motor oil for the hydraulic fluid.

Well anyway I decided to repeat the steering and lift test. No matter how much steering I do, I can still lift slowly with an empty bucket. My test last year, I was lifting a full load. You should have max psi and volume at the joystick valve when lifting a heavy load, with steering at neutral.

I called Keith and he asked Terry, about the priority setup on the steering. The answer went something like this. Steering has priority in any situation. With a little bit of steering, some fluid goes to the steering circuit, and the excess is routed to the joystick valve. The relief for the steering and lift is in the steering assembly. If you are lifting, and then steer just a little, voluming is reduced to the lift valve, and the lift sequence slows down. If you go to the stop on the steering, the relief will relieve pressure, and both circuits will slow down, because there is another outlet for the fluid. .
With my steering at the supposed limit, my steering wheel will keep on turning slowly. This maybe caused by leakage in the steering valve.

The best place to put a pressure gage would be at the pressure line going into the steering assembly. If you are going to do the plug in gage thing, using quick disconnects, another place would be at the pressure line going into the joystick valve.

So, how do you interpret the readings. You should know that you will only see pressure when work is being done. For instance, neutral steering, and no lift or tilt, you would see little or no pressure on the gage. As soon as you steer, the pressure will show an increase, and when you get to the limits, you would see max pressure before the relief valve kicks in. If the gage is at the joystick valve, and neutral steering, you will see pressure only when you are lifting, and will max out at the limits of the cylinder. The max pressure that you should see is the relief pressure in any situation. That's why it is important to only mess with the relief valves using a gage. You could probably tweak it a little bit, to get more lift/tilt, but try and stay below the max pressure of the individual components. Should you have two gages in the steering and lift circuits, they will tell you exactly what is happening, using common sense.

Using that $15.00 gage will allow you to troubleshoot your complete hydraulic system, and perhaps save you many bucks .

Did not mean to get long winded here. Good luck to all.

 

[woodlandfarms]

Nice to see you are risking the Kubota's life by the fire and not your Power Trac's!

The guy in the kubota went back down the hill and brought up his dozer. Made quick work, although we are STILL burning those piles. I keep finding stuff, and I feel like Beavis... Fire Fire Fire

 

[woodlandfarms]

JJ. I love your longwinded ness. that said, I don't get some of the things you say but try to figure them out. I appreciate all the advice I get from you.

 

[woodlandfarms]

That didn't work.

Terry said I should tear the accumulator controller apart. He suggested I pull a hose off the bottom of the accumulator and inside would be a hex key plug with a pinhole in it. He said the pinhole was blocked. Well, it wasn't....

What is weird with my situation is that the brakes work, which are on the the same circuit. So the problem is beyond the PTO / steering relief valve. It is probably in the accumulator. Might be the accumluator charger....

 

[J_J]

That didn't work.

Terry said I should tear the accumulator controller apart. He suggested I pull a hose off the bottom of the accumulator and inside would be a hex key plug with a pinhole in it. He said the pinhole was blocked. Well, it wasn't....

What is weird with my situation is that the brakes work, which are on the the same circuit. So the problem is beyond the PTO / steering relief valve. It is probably in the accumulator. Might be the accumluator charger....

Carl,

Do you not have three pumps, and one of those pumps is for the steering and lift. I could be wrong on this, but I believe the accumulator is in the drive circuit, and has nothing to do with the steering. The pump for the steering and lift should be the smaller of the pumps it terms of GPM. My steering pump is only 1.5 to 3 GPM. I have replaced both the steering/lift, and the PTO pump. The steering was still working, but was leaking internally. I could only lift about half of the rated load, which is 600 lbs.

 

[catsco]

Our PT425 will sometimes not lift if I have the wheel all the way to one side. If I just let go of the wheel, it then lifts, but holding it to one side, it will not.

MR - that's also been my experience as I posted yesterday.

Seems like 425s work differently depending upon the valving available on the day of assembly!

I was ROTFL when people refer to the "owner's manual" and the "hydraulic schematic".

There is little if any similarity between those works of fiction and my machine.

I say that not to diminish the PT - a great machine that's done all I asked, sometimes more. Just can't figure out why a manufacturer would go to such extremes to NOT provide what the self-service warranty requires at a minimum.

 

[SnowRidge]

Just can't figure out why a manufacturer would go to such extremes to NOT provide what the self-service warranty requires at a minimum.

Must be something in the Tazewell water.

 

[woodlandfarms]

Carl,

Do you not have three pumps, and one of those pumps is for the steering and lift. I could be wrong on this, but I believe the accumulator is in the drive circuit, and has nothing to do with the steering. The pump for the steering and lift should be the smaller of the pumps it terms of GPM. My steering pump is only 1.5 to 3 GPM. I have replaced both the steering/lift, and the PTO pump. The steering was still working, but was leaking internally. I could only lift about half of the rated load, which is 600 lbs.

I may also be using the wrong words. But no, I have 3 pumps. One wheels, one PTO one steering, lift and brakes (did not know brakes were in this circuit).

I have a pressure gauge on the brakes so I know I am getting the goods.

Just got off the phone with Terry. Thought is that it might be back to the relief valve in the PTO block. His thought is that the brakes need only a bit of pressure, and that is what gets by the valve, but not enough to drive the steering and lift.

We will see. He wants me to get the tractor cold, start it, and cycle the brakes 5 times. See if the pressure drops.

 

[Bob999]

I may also be using the wrong words. But no, I have 3 pumps. One wheels, one PTO one steering, lift and brakes (did not know brakes were in this circuit).

I have a pressure gauge on the brakes so I know I am getting the goods.

Just got off the phone with Terry. Thought is that it might be back to the relief valve in the PTO block. His thought is that the brakes need only a bit of pressure, and that is what gets by the valve, but not enough to drive the steering and lift.

We will see. He wants me to get the tractor cold, start it, and cycle the brakes 5 times. See if the pressure drops.

Interesting that PT is producing machines that power the brake tender circuit from different pumps. On my 1845 the brake tender is powered from the variable displacement pump--the one that powers the wheels. Earlier in this thread I posted a diagram that shows that. The diagram I posted was labeled as applying to both the 1845 and 1850.

 

[J_J]

The people at POWER-TRAC must be laughing their as* off at us trying to figure out just what and how they did things. If I were a lawyer, I think that I would start a class action suit involving everyone that had ever purchased a PT, demanding that a service manual be provided to every owner with complete theory of operations, pictures, and schematics for every model and modification they have ever done. They rely on one person to answer all our questions. I don't think most of us would have to call and ask questions if we had decent owners/service manuals and parts manual. They must be afraid or ashamed that they do not know how to make/design a good service manual. A good owners manual is availiable all the time, and we don't put them in a lockup over the weekend either. They get a -5 for technical manuals, and schematics. If every new prospective owner would demand a comprehensive and usable manual with their machine before they purchased, PT might get off their as* and provide same.

I have a Kubota manual for my B9200 that is about one inch thick showing everything from front of the machine to back.