Problem with curl cylinder?

radman1 · Mar 8, 2009

Tried my 5610 TC with 36" tree spade today. This is the first time I tried it on the TC. I could lift the ball of dirt but the curl cylinder would not hold. As I lifted the spade, the tilt cylinder would extend as I lifted. Never could lift the far end of the spade. I had never seen any cylinder do that before. I assume the oil is bypassing in the hydraulic control valve rather than in the seals of the cylinder. Is that possible? Would a check valve on the cylinder stop the forced extension? With the spade not filled with dirt, the spade would tip/settle rather quickly, faster than I believe it should.

J_J · Mar 8, 2009

radman1 said:
Tried my 5610 TC with 36" tree spade today. This is the first time I tried it on the TC. I could lift the ball of dirt but the curl cylinder would not hold. As I lifted the spade, the tilt cylinder would extend as I lifted. Never could lift the far end of the spade. I had never seen any cylinder do that before. I assume the oil is bypassing in the hydraulic control valve rather than in the seals of the cylinder. Is that possible? Would a check valve on the cylinder stop the forced extension? With the spade not filled with dirt, the spade would tip/settle rather quickly, faster than I believe it should.

Does the curl cylinder have full range, and does it go to the relief mode when you are at the end stops. It almost sounds like a float valve is activated. Are the hoses connected correctly. Perhaps the curl cylinder is switched with the lift cylinders at the valve.

radman1 · Mar 8, 2009

The cylinder otherwise behaves normally. Full extension and retraction. Goes into relief at both ends of range. Haven't changed any hoses, fluids ect. The joystick functions normally. Unit is about 6 months old.

radman1 · Mar 9, 2009

Talked with dealer this am. He thinks it is more likely the cylinder rather than the control valve, but could be either. May have blown a seal in the cylinder or the nut on the cylinder ram could be loose allowing oil to bypass.

J_J · Mar 9, 2009

It would seem like if the cylinder goes into relief on push and pull, then it should not be a cylinder problem. In your first post you said that you could not lift the tip of the tree spade, but if the cylinder is working normally with relief. Was the cylinder extended when you went into the ground, say at a 45 degree angle? Something is not making sense here.
Can you put the tip of the spade on the ground and raise your front wheels by using curl cylinder, and will it stay there ?

DEWFPO · Mar 9, 2009

After we changed out a hose, I was curling up, it stopped and started to 'uncurl' even though I was still trying to curl up and then it finally began to curl up again. I attributed that to air in the system since we had just changed a hose.

My curl cylinder will not hold pressure well, even with the engine running the curl will drop flat within 15 minutes. A royal PITA when driving down the road. I'm really wondering if there's a defect somewhere in the curl cylinder hydraulics. My 5600 is only a few months old.

DEWFPO

J_J · Mar 9, 2009

DEWFPO said:
After we changed out a hose, I was curling up, it stopped and started to 'uncurl' even though I was still trying to curl up and then it finally began to curl up again. I attributed that to air in the system since we had just changed a hose.

My curl cylinder will not hold pressure well, even with the engine running the curl will drop flat within 15 minutes. A royal PITA when driving down the road. I'm really wondering if there's a defect somewhere in the curl cylinder hydraulics. My 5600 is only a few months old.

DEWFPO

There is no reason for a cylinder to move from the position that you set it, other than the quality of the valve, etc. There is a leak somewhere. Extend the cylinder and listen for the relief to come on. and retract the cylinder and listen for the relief to cut in. That tells you the pump is putting out the pressure and if you had a gage, you would know the relief pressure. Fluid is being moved somewhere, unless all the air has not been purged. Some of the guys on here say that the air should be purged after a couple of cycles, but there may be voids that the air will never come out unless the cyl is rotated so that the cylinder fittings are at the highest point. There are times when you are compressing fluid and air, and in effect is acting like an accumulator, so when you release the valve, the compressed air will put a force on the piston. I don't believe the fluid will absorb the air trapped inside the cyl. It has to be bleed off in some way. Could be wrong, what say the others.

radman1 · Mar 9, 2009

J_J said:
It would seem like if the cylinder goes into relief on push and pull, then it should not be a cylinder problem. In your first post you said that you could not lift the tip of the tree spade, but if the cylinder is working normally with relief. Was the cylinder extended when you went into the ground, say at a 45 degree angle? Something is not making sense here.
Can you put the tip of the spade on the ground and raise your front wheels by using curl cylinder, and will it stay there ?

With no dirt in the tree spade, the curl cylinder will tip the front of the spade up and down and not go into relief. With the spade on the ground the curl cylinder is in the midportion of its stroke. When I had dirt in the spade, the the boom could lift the back of the spade. As the boom lifted the back of the spade higher, the curl cylinder would extend at least several inches from the weight of the spade/dirt. It would extend without any input/movement from the hydraulic control. It seems like the sheer weight of the lift was causing oil in the curl hydraulic circuit to bypass somewhere.
I can raise my front wheels with the curl cylinder when tipping the spade down and it will stay there.

radman1 · Mar 9, 2009

DEWFPO said:
My curl cylinder will not hold pressure well, even with the engine running the curl will drop flat within 15 minutes. A royal PITA when driving down the road. I'm really wondering if there's a defect somewhere in the curl cylinder hydraulics. My 5600 is only a few months old.

DEWFPO

I think yours is defective and has a leak either in the valve or cylinder. It should not leak down that fast with a normal load on the cylinder. Mine may have been overstressed. Mine now will tip down faster than before but still doesn't sound as bad as yours.
Dealer told me a way to check if the problem is in the cylinder. He recommended removing any attachment from the bobtach. Tip the bobtach back all the way. Remove the hose from the top cylinder and see if any oil come out of the cylinder when the the bobtach is again tipped back by running the hydraulics. If oil comes out, problem is somewhere in the cylinder.
I think your dealer needs to look at yours.

Mine is only 5-6 months old and took it to the dealer today. If its under warranty, I figure it is their problem.

J_J · Mar 9, 2009

What you are doing in this test is to see if you have blown o-rings on the piston in the cylinder, or the shaft has a slight bend in it. You will have to hold the Bobtac back enough to activate the relief, just to see if it will force fluid past the piston, otherwise, it will not take a lot of pressure just to move the attachment. I didn't realize how much pressure it took to raise a bucket with no load, less than a thousand psi on my Power-Trac. You will only see high psi when working the attachment hard, as in full load.