Loader Joystick - Bucket goes down when trying to lift

[Sportsman762]

LD1, I might not have communicated what I wished to convey clearly.

If the spool in the valve is not actuated no flow from the pump will go to the cylinder locking the cylinder in place by not allowing the fluid to move in or out of the cylinder if all the components are functioning correctly. To extend a double acting cylinder (lift loader) in an open center system the valve when actuated will apply pressurized fluid from the pump to the base end and open the return for the rod end. This allows the pressurized hydraulic fluid to flow into the base of cylinder and exhaust the fluid in the rod end to the tank.

To retract the cylinder (lower loader) the valve allows the pressurized fluid from the pump to the rod end and open up the base end to the tank. This allows the pressurized fluid to flow into the rod end and push the fluid from the base end into the tank.

When the loader is in the air, and the valve is in neutral, there should be no fluid flowing to or from the cylinder. The valve has the two lines going to the cylinder blocked off. The loader should stay stable. If the seals on one of the pistons are bad it will allow for internal leakage. This will cause fluid from the butt end to flow to the rod end of the cylinder due to the weight of the loader pushing down on the cylinder. What you will see is that the loader will drift down. If the seals are very bad you will loose lifting capacity and the loader will start dropping as soon as you release the joystick. In theory with a perfect system the rod would not move.

You could even remove the seals and when the valve is in neutral....it will be rock solid.

However if the cylinder seals are worn, there is going to be other leakage and that will allow the rod to move drifting down. Hydraulic valves all have some slight internal leakage. I have a friend who was a hydraulic engineer with Bosch, the OEM's actually can choose how tight they want their valves. Cross Hydraulic, a supplier of where I work offers two tolerances for cylinders. Ag equipment is a lower tolerance valve. Equipment used in food and textile facilities often are a higher tolerance due to issues with hydraulic seepage.

However OP is having the loader drop just after applying pressure. This is due to a bad check valve. Here is an excerpt from the Massey 32A Service Manual including the spelling errors. This is a completely different machine, however the open center hydraulics are the same concept. This is the only option in the trouble shooting section for loader dropping when valve is actuated.

Lift Arms "Drop" with boom in "Raise" and Bucket activated. Malfunction of the lift check valve (integral to control vlve) - Test control valve per "Tests and Adjustements" and repair, or replace, valve as required.

I had bad seals on the piston on one of the bucket cylinders on my Massey. The cylinder would droop down slowly when just mowing the field, and if you had a bucket of dirt it was so bad you would have to apply constant hydraulic pressure to the bucket to combat the drift. It would dump a full load in less than one minute if you did not apply pressure. I have a similar issue with a Ford backhoe boom lift cylinder, and a Ford lift cylinder on another hoe. Repacking the cylinder was the cure.

The sudden drop would indicate a check valve issue, most likely.

here is how to check the internal packing for a Massey 32A loader. The manual for the Ford 550, and 655C state the same basic procedure.

The double-acting hydraulic cylinders may be checked for faulty piston packing through the following procedures:

1. Operate the cylinder and observe its rod for either “settling” into, or coming out of, the barrel.

It is possible for internal leakage to be in one direction only .. . therefore, operate the cylinder in both

directions and allow enough time for evalutation at each extreme of travel.

2. If it is determined that the cylinder rod “settles” into the barrel, proceed as follows:

a. Actuate the suspected cylinder until its rod is fully extended, then place control spool in neutral and shut-off engine. has raised the boom — support it adequately~

b. Carefully disconnect the hose from the ROD END port of the suspected cylinder. Use care when disconnecting the hose — make sure that the correct one is being disconnected. Observe ALL SAFETY PRECAUTIONS.

c. Operate engine and continue to actuate control spool in SAME DIRECTION TO FULLY EXTEND

CYLINDER while observing the rod end port from which the hose was disconnected

CONCLUSION: Ii. oil comes out the disconnected port, the cylinder packing is faulty.

If no oil comes out the port, but the rod enters the barrel (due to the applied external load of lift arms, etc.) the trouble may be due to a faulty circuit relef valve, or valve spool’

Here is how to check the load check valve on the Massey 32A loader. I cannot assure is the correct test procedure for your tractor.

“Load checks” are installed in the control valves and may be checked through the following procedures.

1. Run the engine at a low rpm (without stalling) and slowly move the control lever to operate the circuit to be checked. Pressurize the cylinders in the direction that requires the greatest amount of force against the mechanical leverage of the Loader.

EITHER

2. Operate the other control lever .,. while still slowly activating the one being checked and observing the action of the cylinders.

OR

3. Shut-off engine and continue to move control lever to pressurize cylinder in same direction as in step #1.



CONCLUSION: If circuit being checked loses pressure ... indicated by a “setting” of the cylinders in the circuit ... the “load check” is faulty. (Checking for this loss of pressure may also be done with a pressure

gauge in the suspected circuit. If the “load check” is baQJ, the gauge should indicate a pressure drop, but may quickly recover if the engine is running ... this is because pump gpm will soon catch up with the activated circuits.)

Sorry if everyone out there feels like I’m wrong on the piston seals being bad, maybe I should just keep things to myself. After all anyone with a keyboard is an expert in guessing.

wdchyd, I am sorry if I was rude to you. I am very sorry. It was not my intention to be condescending.

 

[wdchyd]

“I had bad seals on the piston on one of the bucket cylinders on my Massey. The cylinder would droop down slowly when just mowing the field, and if you had a bucket of dirt it was so bad you would have to apply constant hydraulic pressure to the bucket to combat the drift. It would dump a full load in less than one minute if you did not apply pressure.”


Sportsman, the bucket cylinders (used as a Pull cylinder) will drift out under a load with compromised piston seal. Lift cylinders (used as a push) will hold the load with a bad piston seal (after the pressure equalizes between the two sides in the cyl and valve in center condition).

 

[dm-in-mn]

Found a parts diagram for that loader over at Messicks website.

Here is the exploded view. Check valve consists of the parts #5, #4 and #6. Looks like there is one per spool, located in between the work ports.

As mentioned before, either a broken spring or trash holding the check valve open.

ptsg: I have the same diagram printed of in my packet of manuals for this tractor. My valve doesn't look like that valve, however. After blindly googling "hydraulic joystick valve" I came across one that looks very similar to mine, which pointed me to this youtube video ->

(Identifying Koyker Valve Series for Correct Repair Parts - Used on Tractors Less than 80HP by Short Line Parts, LLC) At the 3:44 mark is very similar to my valve. Mine has the same numbers and letters cast into it as the one in the video, but the back side of mine is slightly different, and there is an extra bit sticking out of one of the lower spool spring covers. I may have to get ahold of that company to see if they can help me further identify.

So, I think my valve is a Koyker Valve (I think they are made by Pace Manufacturing)

I have attached a few pictures of my valve (albeit poor quality pictures)
View attachment 698145View attachment 698146

I can't find much information on these. I'm not even sure where the check valve would be on this valve.

First thing I would try would be Swap the lift and curl. (provided you have non-regen curl). Second thing I would do would be to test the cylinders.

LD1, I will certainly try this if the check valve line of thinking doesn't work. I am not a hydraulics expert, so please forgive me if it does end up being the lift cylinders.

Sorry if everyone out there feels like I’m wrong on the piston seals being bad, maybe I should just keep things to myself. After all anyone with a keyboard is an expert in guessing.
OP please enlighten us when you find the problem.

I will certainly share the solution once its found. If it isn't a check valve issue, I will test the lift cylinders.

LD1, I might not have communicated what I wished to convey clearly.

If the spool in the valve is not actuated no flow from the pump will go to the cylinder locking the cylinder in place by not allowing the fluid to move in or out of the cylinder if all the components are functioning correctly. To extend a double acting cylinder (lift loader) in an open center system the valve when actuated will apply pressurized fluid from the pump to the base end and open the return for the rod end. This allows the pressurized hydraulic fluid to flow into the base of cylinder and exhaust the fluid in the rod end to the tank.

To retract the cylinder (lower loader) the valve allows the pressurized fluid from the pump to the rod end and open up the base end to the tank. This allows the pressurized fluid to flow into the rod end and push the fluid from the base end into the tank.

When the loader is in the air, and the valve is in neutral, there should be no fluid flowing to or from the cylinder. The valve has the two lines going to the cylinder blocked off. The loader should stay stable. If the seals on one of the pistons are bad it will allow for internal leakage. This will cause fluid from the butt end to flow to the rod end of the cylinder due to the weight of the loader pushing down on the cylinder. What you will see is that the loader will drift down. If the seals are very bad you will loose lifting capacity and the loader will start dropping as soon as you release the joystick. In theory with a perfect system the rod would not move.

However if the cylinder seals are worn, there is going to be other leakage and that will allow the rod to move drifting down. Hydraulic valves all have some slight internal leakage. I have a friend who was a hydraulic engineer with Bosch, the OEM's actually can choose how tight they want their valves. Cross Hydraulic, a supplier of where I work offers two tolerances for cylinders. Ag equipment is a lower tolerance valve. Equipment used in food and textile facilities often are a higher tolerance due to issues with hydraulic seepage.

However OP is having the loader drop just after applying pressure. This is due to a bad check valve. Here is an excerpt from the Massey 32A Service Manual including the spelling errors. This is a completely different machine, however the open center hydraulics are the same concept. This is the only option in the trouble shooting section for loader dropping when valve is actuated.


I had bad seals on the piston on one of the bucket cylinders on my Massey. The cylinder would droop down slowly when just mowing the field, and if you had a bucket of dirt it was so bad you would have to apply constant hydraulic pressure to the bucket to combat the drift. It would dump a full load in less than one minute if you did not apply pressure. I have a similar issue with a Ford backhoe boom lift cylinder, and a Ford lift cylinder on another hoe. Repacking the cylinder was the cure.

The sudden drop would indicate a check valve issue, most likely.

Sportsman762, this is what my understanding is, and why I can't see it being a lift cylinder issue. But, again, I know very little about hydraulics. I assume that since the cylinders otherwise have very little "drift" that the seals are OK. The check valve line of thinking makes sense to me. Unfortunately I have no idea where on my valve body the check valve(s) is/are.

“I had bad seals on the piston on one of the bucket cylinders on my Massey. The cylinder would droop down slowly when just mowing the field, and if you had a bucket of dirt it was so bad you would have to apply constant hydraulic pressure to the bucket to combat the drift. It would dump a full load in less than one minute if you did not apply pressure.”


Sportsman, the bucket cylinders (used as a Pull cylinder) will drift out under a load with compromised piston seal. Lift cylinders (used as a push) will hold the load with a bad piston seal (after the pressure equalizes between the two sides in the cyl and valve in center condition).

This seems counter-intuitive to me. If the pressure equalizes on either side of a bad seal, wouldn't the weight of the load create an imbalance which would cause the cylinder to drift down? Wouldn't fluid leak past? Maybe I'm just not understanding (well, clearly not understanding)





Thank you all for the help thus far.

 

[dm-in-mn]

Looks like the above attachments didn't work. Here's a retry.

 

[Sportsman762]

I looked more into what wdchyd posted and discovered I was wrong on some of my understandings on how push cylinders react. Also wdchyd has quite a bit of experience in hydraulics so what he is stating is worth looking into. In my prior posts I list test procedures that should help OP pinpoint issues. Starting with the cylinder test, then going to the load check test.

“I had bad seals on the piston on one of the bucket cylinders on my Massey. The cylinder would droop down slowly when just mowing the field, and if you had a bucket of dirt it was so bad you would have to apply constant hydraulic pressure to the bucket to combat the drift. It would dump a full load in less than one minute if you did not apply pressure.”


Sportsman, the bucket cylinders (used as a Pull cylinder) will drift out under a load with compromised piston seal. Lift cylinders (used as a push) will hold the load with a bad piston seal (after the pressure equalizes between the two sides in the cyl and valve in center condition).

The video shows why push cylinders react the way that wdchyd explains.

This seems counter-intuitive to me. If the pressure equalizes on either side of a bad seal, wouldn't the weight of the load create an imbalance which would cause the cylinder to drift down? Wouldn't fluid leak past? Maybe I'm just not understanding (well, clearly not understanding)

My thoughts were the same as yours DMinMN until I investigated more.
Post what you find out. I am learning here as well.

 

[RickB]

The reported symptoms clearly indicate to me there's a malfunction in the load check valve. Failure of one or both lift cylinder piston seals would exhibit drift at other times and none is reported by the OP. It really is that simple.

 

[LD1]

I looked more into what wdchyd posted and discovered I was wrong on some of my understandings on how push cylinders react. Also wdchyd has quite a bit of experience in hydraulics so what he is stating is worth looking into. In my prior posts I list test procedures that should help OP pinpoint issues. Starting with the cylinder test, then going to the load check test.

The video shows why push cylinders react the way that wdchyd explains.


My thoughts were the same as yours DMinMN until I investigated more.
Post what you find out. I am learning here as well.

Hey....no thanks or recognition needed

I am glad you finally understand. In the future....you will be one less person continuing to spread false info that loader drift = bad seals.

 

[wdchyd]

Dm-in-mn,

Try something for me:

tractor at idle.......empty bucket...operate DCV to lift cylinders.....from full stroke of the valve spool, cylinders extend halfway up stop movement quick.
Have someone watch the cylinders if you can’t see them.

Do the cylinders?:

A..........stop immediately and hold rock solid?

or


B..........stops, slightly creeps down (1/4 -1/2”).....then holds rock solid

 

[dm-in-mn]

This is incorrect information. Bad lift seals will NOT cause the cylinder to drift down. You could even remove the seals and when the valve is in neutral....it will be rock solid.

Bad seals "can" cause the loader to drop a bit though when trying to lift.....especially if you have a heavy load and are trying to lift/move very slowly. Heres why:

The base end of the cylinder is the side you are applying pressure to to lift the loader. The rod side is where fluid is expelled and returns to tank. So moving the joystick does TWO things. 1. Allows high pressure oil to enter the base end of the cylinder. 2. Allows oil out of the rod side of the cylinder to return to tank.

If you have bad seals....and they are leaking FASTER than you are applying high pressure oil.....the oil can go past the seals and return right back to tank.

Lets say you have bad seals that will allow 2 GPM past them. And your tractor is a 8GPM hydraulic system. If you are trying to feather the load (to lift slowly) you might only be allowing 1 GPM to enter the cylinder. But you have also given a path for 2 GPM (past the seals and back through the valve) for oil to exit the cylinder. So when 2GPM leave the cylinder and only 1GPM enter the cylinder....the result is the cylinder drops. ITs not until you move the joystick further and supply MORE than 2 GPM that it will actually start to lift.

The likely culprit is the check valves though. Sometimes called anti-drop valves. But BOTH those and the cylinders are easy enough to test.

First thing I would try would be Swap the lift and curl. (provided you have non-regen curl). Second thing I would do would be to test the cylinders.

I looked more into what wdchyd posted and discovered I was wrong on some of my understandings on how push cylinders react. Also wdchyd has quite a bit of experience in hydraulics so what he is stating is worth looking into. In my prior posts I list test procedures that should help OP pinpoint issues. Starting with the cylinder test, then going to the load check test.

The video shows why push cylinders react the way that wdchyd explains.


My thoughts were the same as yours DMinMN until I investigated more.
Post what you find out. I am learning here as well.

Aaah! That makes total sense now! Sportsman762's video helped tremendously. If the internal seals failed, there can't be any creep, as the actual rod would have to displace more or less fluid, which it cannot because of the valve. I always enjoy learning new things.

I do not think this is my problem, however. I swapped the bucket and arm functions on the loader as a test. After swapping, there was no drift in the arms, but the bucket would drift. I as able to slowly lift the arms as I would expect with minute movements. This tells me that it's the valve, and not the cylinders (unless I'm missing more hydraulic black magic that I don't know about)

I don't actually see a check valve on this valve body. So I called that company that had the video I posted above that was able to help me identify the type of valve I had. I explained my problem, and basically what I was told was to replace the entire valve, it's not worth rebuilding. Does this sound like the acceptable solution here? They said they have lots of experience with these valve bodies, and that most of the time they are just so worn out internally that a rebuild kit does very little. Wow.

Thoughts? My immediate thought is that I'm going to have to live with the drift for now, and buy a good quality replacement in a few months once the budget allows.

Dm-in-mn,

Try something for me:

tractor at idle.......empty bucket...operate DCV to lift cylinders.....from full stroke of the valve spool, cylinders extend halfway up stop movement quick.
Have someone watch the cylinders if you can’t see them.

Do the cylinders?:

A..........stop immediately and hold rock solid?

or


B..........stops, slightly creeps down (1/4 -1/2”).....then holds rock solid

wdchyd, I assume you are trying to get at what LD1 is suggesting. I can certainly try this if my process of elimination above has not proven that its a valve problem, and not a cylinder problem. Again, after swapping loader functions, the problem moves to the bucket instead of the arms.







Again, thank you all for the input.

 

[wdchyd]

That’s great, you’ve found the problem.