I am building a car scissor lift.I had to cut down the length of the used cylinders I picked up off a friend.I replaced the umbrella seals .The bores are 3 inches and the pump I got off my friend is a brown and sharp power unit with. 5 hp 3 ph motor and produces 1700lbs by my new installed guage.
Now the problem.I have this about 90 % done and wanted to give it a test with a car on it?Put my kids car on it and it would start to raise evenly then the right side would stop raising and left would keep on going.I have all new hoses and the feed line feeds a t-fitting and goes to the 2 cylinders so all is even as far as feeding the same.I tried switching lines and no change.I gave up and switched cylinders from side to side to see if something was binding and determined that the cylinder is malfunctioning.Acts same on other scissor so now the head scratcher .I took the cylinder apart and checked everything and all looks ok.When there is no load on the lifts they move fine all the way up and then collapse by just the lifts own weight so no binding .
Is there a way I can test the strength of this cylinder when I put it back together? I just don't see why it isn't pushing as hard as the other cylinder.
The way I proved to myself that it wasnt a mechanical binding was to separate the 2 scissors ."Torque tube tying them together"..
I put my lawn mower on one side and it wouldn't lift a 1000lb mower with the bad cylinder.I then switched the cylinder and the other side that would lift the car fine now wouldn't even lift the mower so no binding was proven.I am really stumped and have a huge oiled up floor from messing with everything.
Any ideas guys?
Ps.there is no oil bypassing the umbrella seals.These were double acting cylinders and The outer fitting is open and no oil is passing the seal.And one other thing.When it would raise part way up and I stopped the pump but kept the pressure on the cylinders it would hold the load and not drift down..makes no sense.