creepy forks

i have an old hyster, the tag is all smashed so i dont know the numbers on it. it looks like a h40xmm ser. h177g538090b that i worked on awhile back. it has the three mast lift cylinders on it. where can i find id numbers on it? im thinking i need to reseal the cylinders. when i lower the forks they creep down a few inches after i let the lever go. tried all kinds of lever action but it still creeps down a few inches. does it with or without a load. when i raise the forks it may creep down a few milimeters after stopping. it dosent seem to be the valve so im thinking cylinders. it does it on all cylinders. also the center cylinder will go up after the twins go up with a load on it. dont know if that could be a root cause to my problem.

Does it creep a few inches and then stop, or will it keep dropping? If it stops, I'd guess it has some air in the cylinder that you can bleed out through a screw at the top of the cylinder.

On the center cylinder and twins, are you talking about a three stage telescopic cylinder? The different stages going up in different order, is not a problem in itself.

Is it leaking fluid out of the piston seal on the gland ? If not the cylinders are good
Pj

powerjoke said:

Is it leaking fluid out of the piston seal on the gland ? If not the cylinders are good
Pj

Click to expand...

Duh! thanks, don't know how I overlooked that one.

the gland doesnt leak. i cant remember exactly how the piston is setup, but if i remember right there is a poly seal on the piston and some kind of bypass valve to let the oil through to the backside of the piston. they are not telescoping cylinders. if you are familiar with yales and hysters there are three cylinders that provide lift on alot of them. i will quess that the single cylinder goes up 1st cause it has more surface area than the other two combined. also i still need to get some kind of vin number off this machine so i can order parts if need be.

I've never noticed that setup, could you post a pic? If the cylinders only have one port each (one hose) then the seals not leaking still means the cylinder's not leaking. Does it keep dropping?

Sorry, no help on finding a number.

i found the numbers. that setup is used on other brands of lifts too. it is a one hose gravity down system. one hose to each cylinder, fed by a, tee, that could also be some kind of proportional valve.
it does not keep dropping. there are check valves in the bottom of the of the rods where the pistons are. they could be sticking.
i get the feeling that the piston seals are colapsing when i relieve the pressure in the cylinders, making the forks creep down till enough pressure builds up to make the seals expand against the cylinder walls.

managed to get the model. GLP050PGNUAE086. what should my lift pressure be at relief?

Why Don't you consult a mechanic.

Uh....... U saying nobody on here's a mechanic or do you have a bone to pick with this guy inparticular ? Seems that you signed up just to make a post ?

To the OP ops there anyway that chain tension would cause the wrong stage to go up first ? I have a hustler 80xl I wonder if it's the same mast I'll look at it.
Pj

Havent thought or heard about chain tension being a factor in this. I will have to check it the next time I come across this lift.