Hi all, I am rebuilding a cylinder on an old forklift. It's probably 60-70 years old and is from a Gladden-Haas tractor conversion. I have it all apart and am working on sourcing new seals however my main question is whether it is plumbed correctly. I believe it is supposed to be a single acting cylinder and should gravity bleed on the down stroke, but it appears to be getting pressure when moving the lever into the down position. Is this harmful to the gland seals? Is there any way to fix it without replacing the control valve? It worked this way for decades but I am told it has always leaked a bit around the rod. Thanks for any info
Not all forklifts are gravity down. Had a Zeteor that had power down. Least I think it was that one.
Whoever decided it needed black pipe/ fittings in the hydraulic system, should get a swift kick in the nuts.
Yeah those are getting replaced as well.
60-70 years ago, hydraulics ran at 500-800 psi. "High pressure" hydraulics ran at 1000psi. Black pipe fittings are quite capable of withstanding 1000psi. I've got a 1953 articulated tractor crane, with an AW-6 IH tractor power unit. The front crankshaft mounted hydraulic pump runs at 800psi for the lift cylinders, and the steering cylinders run at 500psi. The hydraulic system is all black pipe and fittings, and all the seals were originally made of leather!
Common on old stuff. Yeah I know "will kill a bus load of nuns headed to rescue kids at a burning orphange". But, it's worked fine for 60 years, don't fix what's not broke. Hydraulics until maybe 70s? often ran at under 1000psi too.