Construction and other equipment - AC Forklift Hydraulics

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AC Forklift Hydraulics

Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Construction and other equipment
Forum Description: everything else with orange (or yellow) paint
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=159231
Printed Date: 02 May 2025 at 5:53am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com

Topic: AC Forklift Hydraulics

Posted By: Famous
Subject: AC Forklift Hydraulics
Date Posted: 21 Mar 2019 at 1:36am

I have an old AC forklift that has a problem with the tilt cylinders every time that I put a load on it and tilt it back it goes back down. I checked the cylinders and they don't seem to be leaking and they are non serviceable they are welded and don't have a screw out end. I also did change a line that was leaking on one side and the other side has a small leak I think. I also did change the fluid and does anyone know the capacity on these it has no dipstick I measured out 3.5 gallons and put the same amount in. I put ATF in it.

Replies:

Posted By: jaybmiller
Date Posted: 22 Mar 2019 at 6:16am

If you mean when it tilts back,release leaver, it then tilts forward, I think the control valve has a small blockage or bad O-ring or ?? Something that isn't allowing the valve to fully close,so oil leaks internally. You don't say which model lift, but my FPD50 tank cap has a 'dip stick' attached to it. I'd say fillup yours to say 2" below where the stem and top of tank meet.

you can try http://www.liberatedmanuals.com" rel="nofollow - www.liberatedmanuals.com for a manual, 100s of them there.

Jay

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3 D-14s,A-C forklift, B-112
Kubota BX23S lil' TOOT( The Other Orange Tractor)

Never burn your bridges, unless you can walk on water

Posted By: Joe(TX)
Date Posted: 22 Mar 2019 at 5:32pm

It's probably the cylinders leading at the piston seals. It seems to be the most common cause, at least all the forklifts and loaders I've had.

Leaking o rings on the valve cannot cause the problem. They only control external leakage. There are no internal seals in the valve.

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1970 190XT, 1973 200, 1962 D-19 Diesel, 1979 7010, 1957 WD45, 1950 WD, 1961 D17, Speed Patrol, D14, All crop 66 big bin, 180 diesel, 1970 170 diesel, FP80 forklift. Gleaner A

Posted By: Jim.ME
Date Posted: 22 Mar 2019 at 6:14pm

You say you checked the cylinders and they don't seem to be leaking. How did you check them? Visually, as you didn't see a leak out of the cylinder at the rod? The piston packings could be leaking internally which you can't see.

I don't know about those tilt cylinders but it doesn't seem that tilt cylinders would be non-serviceable (100% welded). Are you sure the gland on the rod end doesn't unscrew from inside the tube? If there is a bead of weld on that end I would wonder if someone had a problem and did that as a one time fix, for their use.

How much slop in the valve? If the centering spring was bad the valve spool might not be in center, closed to both sides of the cylinders, when you let go of the handle.

The model info and some photos might help.