L2250 Kubota with loader bucket.
Problem: Bucket will not roll back or curl upwards
Bucket will only 'dump' only or curl down; the bucket will not roll back or curl up.
A tree branch struck the control valve arm. Since the impact, the bucket will not curl and the seal shaft into the valve body weeps very slightly, was dry before, now a touch of wetness on top of the valve (a little oil goes a long way).
The dump/rollback control valve moves to its center position and to either spring-loaded end positions, like normal.
Loader arms lift and drop OK and boom cylinders hold position when off. Other hydraulics work OK.
Hoses are in good shape, no leakage.
Tractor is about 30 years old, always stored in a shed. Residential service: 4-6 hours/year of operation
The hydraulic fluid level is well above the line in the sight glass. Filter was changed 3 years ago (20 hours?). Other hydraulic circuits work OK.
My only experience with hydraulics is automotive brakes, a far stretch from powered hydraulics, so I need advice in repairing this.
1. valve or cylinder?
I have heard of a leaking cylinder failing to actuate. There is no visible leakage around the cylinder seals.
How does one isolate the problem to either the control valve or the cylinder, and which (rotation) cylinder?
2. Are spool control valves repairable? Are replacement spool valves available or is only the whole control valve assembly available? Are there 3rd party (non-OEM) valve assemblies?
3. Hydraulics always have a pressure relief valve. Can a pressure relief valve stick open so that pressure fails to build? Can pressure relief valves be replaced independently of the valve body assembly? Are they commercially available?
4. Comments in the manual about running the bucket up and down to purge the hydraulic system of air leads me to believe that when replacing components, air does not need to be bled out of the system; that the moving oil clear the system of air. Is that true?
5. Other than cleanliness, are there considerations for repairing hydraulics?
Problem: Bucket will not roll back or curl upwards
Bucket will only 'dump' only or curl down; the bucket will not roll back or curl up.
A tree branch struck the control valve arm. Since the impact, the bucket will not curl and the seal shaft into the valve body weeps very slightly, was dry before, now a touch of wetness on top of the valve (a little oil goes a long way).
The dump/rollback control valve moves to its center position and to either spring-loaded end positions, like normal.
Loader arms lift and drop OK and boom cylinders hold position when off. Other hydraulics work OK.
Hoses are in good shape, no leakage.
Tractor is about 30 years old, always stored in a shed. Residential service: 4-6 hours/year of operation
The hydraulic fluid level is well above the line in the sight glass. Filter was changed 3 years ago (20 hours?). Other hydraulic circuits work OK.
My only experience with hydraulics is automotive brakes, a far stretch from powered hydraulics, so I need advice in repairing this.
1. valve or cylinder?
I have heard of a leaking cylinder failing to actuate. There is no visible leakage around the cylinder seals.
How does one isolate the problem to either the control valve or the cylinder, and which (rotation) cylinder?
2. Are spool control valves repairable? Are replacement spool valves available or is only the whole control valve assembly available? Are there 3rd party (non-OEM) valve assemblies?
3. Hydraulics always have a pressure relief valve. Can a pressure relief valve stick open so that pressure fails to build? Can pressure relief valves be replaced independently of the valve body assembly? Are they commercially available?
4. Comments in the manual about running the bucket up and down to purge the hydraulic system of air leads me to believe that when replacing components, air does not need to be bled out of the system; that the moving oil clear the system of air. Is that true?
5. Other than cleanliness, are there considerations for repairing hydraulics?