Hydraulics wont lift a load
Posted: Tue May 16, 2017 3:52 am
My grandfathers Dexta
, early model,lights on outside of nose, single stage clutch, has been out of use and laid up in one shed or another from the mid 90's with gearbox issues.
Fixed them in 2004/05 and did a bit of body work, not got around to putting it back together fully till yesterday.
Now she is out the shed and running, first thing I did was put a transport box on that has maybe 20 paving slabs in, no
weight at all really, but it won't even lift it an inch off the ground.
With no weight,the arms lift fully and go all the way to allow trailer hitch release.
Put a pressure gauge on the aux service valve. It initially goes up to 1400 psi, then drops to 800 as inloader valve releases pressure. This seems too low, was thinking 2400 psi sort of figure.... but it was an old ropey gauge.. not sure how accurate , and after 18 or more years since ladt use, cant find the 3000 psi gauge.
Back end oil is good, clear not milky,
I put the transport box back on , and lifted it with a forklift.
Once up, with the engine stopped, the hydraulics do stay up... 20 or so paving slabs in it and it does drop slowly, 6 inches in half and hour.
So that seems to eliminate:
cylinder piston rings leaking
Ram Cylinder safety valve
Check Valve.
I do notice though that the aux service outlet fitting was leaking when the system is under pressure with weight on the lift arms. So I replaced the trailer pipe fitting. But this does indicate I guess that the AUX service push pull valve under the seat is allowing oil out to the aux fitting , even when the valve is in the in (lift arm position)
, early model,lights on outside of nose, single stage clutch, has been out of use and laid up in one shed or another from the mid 90's with gearbox issues.
Fixed them in 2004/05 and did a bit of body work, not got around to putting it back together fully till yesterday.
Now she is out the shed and running, first thing I did was put a transport box on that has maybe 20 paving slabs in, no
weight at all really, but it won't even lift it an inch off the ground.
With no weight,the arms lift fully and go all the way to allow trailer hitch release.
Put a pressure gauge on the aux service valve. It initially goes up to 1400 psi, then drops to 800 as inloader valve releases pressure. This seems too low, was thinking 2400 psi sort of figure.... but it was an old ropey gauge.. not sure how accurate , and after 18 or more years since ladt use, cant find the 3000 psi gauge.
Back end oil is good, clear not milky,
I put the transport box back on , and lifted it with a forklift.
Once up, with the engine stopped, the hydraulics do stay up... 20 or so paving slabs in it and it does drop slowly, 6 inches in half and hour.
So that seems to eliminate:
cylinder piston rings leaking
Ram Cylinder safety valve
Check Valve.
I do notice though that the aux service outlet fitting was leaking when the system is under pressure with weight on the lift arms. So I replaced the trailer pipe fitting. But this does indicate I guess that the AUX service push pull valve under the seat is allowing oil out to the aux fitting , even when the valve is in the in (lift arm position)