Any Hydraulics Gurus? Strange Problem with Hoist.

[morerevsm3]

if the 1 on your drawing you call primary is the smaller of the 2, it is plumbed correctly, there has to be a method in the primary cylinder to phase them correctly, this is normally done by spiral grooves in the bore right at the end of the stroke or a valve through the piston which is mechanically opened at the end of stroke that allows oil to bypass piston, and carry air with it (back to reservoir). disconnect both cylinders from top of hoist so you can fully extend cylinders without hitting limit switch or floor, hold so oil flows for approx 1 minute, hook it up and try again, should be fixed

[JZK25]

Ok, there is a valve as you have described in the top of the secondary cylinder. Would that need adjusting perhaps?

I am not sure exactly what you are describing here - "disconnect both cylinders from top of hoist so you can fully extend cylinders without hitting limit switch or floor, hold so oil flows for approx 1 minute, hook it up and try again, should be fixed"

There is no limit switch on the rams or carriages, only on the overhead section for vans etc. You can keep the pump going after the hoist is fully raised, it just labours a lot.

Thanks for the info re the grooves/valving. I will talk to the ram rebuilder about it and see if we can sort something out.

[morerevsm3]

hoist is probably on floor before cylinders completely extended, so you would need to let top half go up to reach the end of the stroke to allow system to phase, the phasing valves refered to in above post would be internal

http://www.ptehydraulics.com.au/
click on standard welded cylinders, then slp, you can see "poppet valve", this is to phase cylinders and bleed air out

[BigMuz]

http://members.westnet.com.au/ptehyd/phasing.html

[JZK25]

Thanks Muz and Morerevs, champs.

[BigMuz]

IS this still for sale?