Loader slowly lowers itself when under a load.

[farmiguy]

I have a MT225s with loader and front mount snowblower. Last summer I used the bucket hook and a chain to lift the front of my smaller lawn tractor. After about 15 minutes the bucket had lowered the lawn tractor about 4-5 inches. Today I left the snowblower raised to let the snow melt out after I was done snow blowing and a few hours later it had lowered itself a few inches.

Is this normal? Can an adjustment be made?

The reason that I am questioning it is because I had a Cub Cadet 7305 with loader for over 20 years and only on rare occasions would it lower itself (ie, when carrying 700-800 lb rocks for long distances) the bucket would uncurl slightly.

 

[oldnslo]

Is this drifting down something that has slowly gotten worse or a sudden change?

Note: All hydraulic spool type directional valves leak. Some more than others.

There are two potential leak paths on loader lift cylinder circuit. One is through the directional valve and other is the piston seals on the cylinders. The directional valve is all metal to metal seals and if the centering spring mechanism is not returning to “home” position properly it can allow increased leakage.

 

[KCTractors]

I have a MT225s with loader and front mount snowblower. Last summer I used the bucket hook and a chain to lift the front of my smaller lawn tractor. After about 15 minutes the bucket had lowered the lawn tractor about 4-5 inches. Today I left the snowblower raised to let the snow melt out after I was done snow blowing and a few hours later it had lowered itself a few inches.

Is this normal? Can an adjustment be made?

The reason that I am questioning it is because I had a Cub Cadet 7305 with loader for over 20 years and only on rare occasions would it lower itself (ie, when carrying 700-800 lb rocks for long distances) the bucket would uncurl slightly.

My MT357 does the same thing. I had a MT342 and it did that also. The Dealer said that was normal. I have a Case 530 CK and a Ford Industrial 4031 with Ford 723 loader and both of these tractors will not settle abit. Probably better machining in those older units.

 

[farmiguy]

Is this drifting down something that has slowly gotten worse or a sudden change?

Note: All hydraulic spool type directional valves leak. Some more than others.

There are two potential leak paths on loader lift cylinder circuit. One is through the directional valve and other is the piston seals on the cylinders. The directional valve is all metal to metal seals and if the centering spring mechanism is not returning to “home” position properly it can allow increased leakage.

Problem does not seem to be getting worse. I have not had the the loader on for a couple of months because the S/B has been frequently in use. I did think it was interesting that both implements slowly lowered themselves. Thus, probably the 4 way valve slow leak? It is the only component that both loader and S/B use. Does this thinking make sense?

 

[oldnslo]

If the snowblower is totally separate lift system then yes your thinking is correct on the only common component would be the directional control valve.

 

[GS650GL]

All hydraulic implements will settle over time. Even if the cylinder piston seals and control valve are good, a small amount of oil will seep through somewhere. If it goes down fast enough that you can actually see it move while watching it, then that's too fast. Large farm tractors and some industrial equipment have load check valves in the loader control valve to prevent the implement from lowering unless the lever is moved to the lowering position with the engine running. Small tractors do not have load check valves in the loader control valve, so some oil is going to go between the spools and the bores in the valve. LS had some trouble with certain cylinders on some models. LS does not make these cylinders or loaders. They are made by Taesung or Ansung, depending on the model. Early LL1101 loaders on MT1 tractors had defective bucket cylinders that would leak down rapidly. The cylinder tubes were rusty inside from the manufacturing process. The cylinders are washed before being painted and wash water leaked inside causing rust. They now improved the plugs in the cylinder ports so water can't leak in during the wash process. Recently, some new model snowblower subframes (not for 225S) are having issues with lift cylinders leaking down rapidly.

 

[etpm]

I don't understand how leaky piston seals can cause the cylinder to to leak down. If we take it to the extreme just imagine a cylinder without a piston. Pushing on the rod will try to compress the oil and since the oil is almost incompressible the rod won't move. And pulling on the rod will cause a suction and the only way the rod can move is if the oil starts to vaporize. What am I missing?
Eric

 

[farmiguy]

If the snowblower is totally separate lift system then yes your thinking is correct on the only common component would be the directional control valve.

Yes, it is a separate lift system. It is a nicely designed quick attach system with a single lift cylinder that can be used with either the S/B or a snow plow blade. Not sure but I think a sweeper as well.

 

[oldnslo]

I don't understand how leaky piston seals can cause the cylinder to to leak down. If we take it to the extreme just imagine a cylinder without a piston. Pushing on the rod will try to compress the oil and since the oil is almost incompressible the rod won't move. And pulling on the rod will cause a suction and the only way the rod can move is if the oil starts to vaporize. What am I missing?
Eric

Eric,
A cylinder cannot retract without an external flow path. The reason for this is the volume difference of the rod. That is why if loader is drifting down it must be connected to the directional valve to have a flow path for oil to escape to tank. If the piston seals on the cylinder is leaking the load induced pressure is now transferred to both ends of the cylinder and both ports of the directional valve effectively doubling leakage flow through the directional valve.

A cylinder can extend without an external flow path since rod end volume is less than cap end.

Yes it may draw a little vacuum but it will still extend with external load pulling on the cylinder.

Hope these explanations make sense

 

[flyerdan]

An internal leak will allow the force to push the piston down; the oil in the back is now in the front part of the cylinder. Since they are plumbed together before the valve, the cylinders will tend to equalize, thus the good cylinder will gain and lose oil via the other side until the force is removed and equilibrium is re achieved.