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| We have a Ford TW25 that won't build up full hydraulic pressure, looking for ideas. We think the problem came on suddenly, a baler was functioning properly late in the week, then Monday morning the tractor couldn't lift the tail gate more than 1/4 open. A gage on the remotes shows we are only getting around 1300 psi. Dead headed, no flow.
Tractor: TW25, later hydraulic system, has the auxiliary engine mounted pump.
No trailer brake. Normal relief valve setting is 2500 to 2600 psi.
Here are some tests we've done, some tests are per the service manual.
1. pressure tested on lh and rh remotes and is the same on both the raise and lower side.
2. pressure stays at 1300 psi when two remote levers are activated simultaneously.
3. pressure stays at 1300 psi when the 3pt arms are raised.
4. Lifted a 15' 3pt drill half full of seed, acted normal although we don't have a pressure reading on this portion of the circuit.
We removed several of the components from the tractor looking for missing or damaged orings, binding spools or worn surfaces. We did find a couple of damaged orings and one missing oring. New orings were installed in these locations.
Here are the items we have torn down, inspected and repaired:
a. filters changed, old filters cut open and inspected.
b. main relief valve
c. in the valve bank above the pump: Unload check valve, Unload valve, Flow control valve.
d. main hydraulic pump in the rear axle cavity. (torn down and inspected for excess wear or blown orings in the end caps ect...)
Have not inspected:
e. auxiliary pump on the lh side of the engine.
f. the valves in the rear axle cavity situated near the 3pt lift cylinder. (the cab
would need to be pulled)
A couple of tests that are good clues:
g. The main relief valve was removed and shims were added under the spring per the service manual. Pulled 0.050" shims and replaced with 0.080" shims (maximum allowable per the service manual) Service manual says each 0.010" shim added will increase the pressure by 100 psi.
Result: no change, pressure at the remotes still 1300 psi.
f. The system can develop 1300 psi at the remotes at an extremely low idle (and) it does not change when the engine is sped up. This to me indicates that the problem is not a worn gear pump)
Has anyone seen this? Any ideas? | |
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