Hello, In the spring of 2019 I paid to have the main mast cylinder for my 1984 Hyster H150F rebuilt. As part of the rebuilding they rechromed the rod (expensive). When that work was done I drained and flushed the system, and thoroughly cleaned the tank. The machine gets sporadic use. I'd say between when the cylinder was rebuilt to the most recent failure there were less than 100 hours of use. I owned it for 10 years without it leaking. Rebuilt it went less than one year before leaking. I'm contemplating rebuilding it myself this time. Any hints of what I should inspect to ensure I don't get a leaky cylinder again. Also I'll note that after rebuild it would always leak down, slowly, but faster than I would like and shorter than it took before it first began to leak before the rebuild. I thought this may have been me not bleeding all the air out. It is now leaking out the top of the cylinder. Thanks!
You might measure the diameter of the rod with a micrometer. Sometimes when people rechrome they go a little undersize which can cause the early failure. I would also recommend looking all the seals over carefully before removing them from the gland nut. Maybe they used after market packing that may have been a will fit. Does the cylinder drift down at all or jump up a little when you go to lower the mast? Might be piston problems in that case as well.
Hi John, Thanks. I guess I'll have to get a micrometer. With or without a load it drifts down over time at what seems the same rate, but I haven't timed it. It takes a while, again haven't measured, but it's not at the point where it isn't usable. I just can't leave something raised for an hour. I can get out of the seat and position dunnage etc without fear of it lowering. When lowering it moves in a controlled way, no jumping. However now that you mention this, I have experienced odd 'jumping' when lifting up on a load. I'll be pulling back on the lever to lift and the load will not move (well under load limit) and then the carriage suddenly jumps up a few inches before moving normally. It started to do this before the rebuild and was hoping the rebuild would cure it. Perhaps one chain is too long causing a bind? Found the bill... Thanks.
Is that a single acting or double acting hydraulic cylinder? does it have just a hose at the bottom? or one at the top also? What you describe with lifting is air in the cylinder, does it still do this with all that leakage? or did it jump only when you had just replaced the cylinder? Definitely get all the air out before lifting any weight with the lift. Does it, or did it ever "jump" when lowering the mast? like hang for a second and then drop a bit, or "chatter" on it's way down? I wouldn't hesitate to rebuild it yourself. Should be fairly straightforward. If it's not, it would be a matter of getting the gland machined to fit new seals if the old ones aren't available.
I don't recall a US made cylinder rod being 3.688 in diameter. I see they also charged you for a honing stone? Another thought is that few if any manufacturers put out packing kits for cylinders anymore. All the cylinders I've had anything to do with in the last ten years only sold individual pieces. You might contact a Hyster dealer parts department and ask some questions.
It has two lines, one at the top and one at the bottom. I seem to remember when I took it out and flushed the system that the top line seem to just lead back to the tank. Which seemed to confuse me. I'll have to double check that. Here's a picture showing the top line took before the first rebuild I believe it still does it with the leakage. I don't typically use it in the winter, so I'm going by memory This brings up a question. What is the correct bleed procedure? It has a bleed port (or what I think is one) up high on the cylinder. What I did was: raise and lower it a few times, then with it lowered crack the bleed port, then raise until fluid came out. When lowering it lowers smoothly, never jumps etc. I can crack the port open just a bit and have it lower nice and smooth. That has always worked well. Could be a clerical error on the invoice, I'll need to measure it myself. I did call the dealer to try to try to get seals for the tilt cylinders and they were no longer available. I'm guessing that will be the same for the mast cylinder. Thanks.
If the top hose goes back to the tank, then that hose is acting as a leak return hose. The cylinder is single acting, which makes sense for a fork lift, no need for downpressure -quite bad. The seals are on the piston then, and the gland seals SHOULDN'T have to hold any pressure at all if the top of the cylinder just returns oil to the tank. I wonder what would happen if you remove that top hose and replace with a short new one that goes right into a bucket? Or blow that line out to see if it's blocked/crushed/plugged. or the oil level is too high in the tank, and the drain gets air locked, or builds pressure because of a blocked vent. The wiper is the top "seal" you see on the rod, that wiper is supposed to wipe the dirt off the rod, not keep the oil in. The seals that keep the oil in are deeper inside the gland, and it's possible they are the wrong size, failed, or were left out entirely because they shouldn't be needed on this cylinder. Sorry, lot of crazy ideas, but not something you'd expect to see, so you got to explain it somehow?
Delmer is correct about the top hose. There may only be a wiper at the top as there isn't supposed to be any pressure there. Make sure that return and the cap and the breather on the tank is open. That little bit of drift isn't a big problem unless that drain hose on the top is plugged or kinked.
Thanks for the ideas. Nice to finally understand why that top line was there. Again going by memory the top seems to leak more after running for a while, so that might point to too full of a tank. I may have filled to the fill level when cold thinking more oil is better I did have the tank breather cap off and looked at the filter in it, I'll have to check it again when things warm up a bit, 8F/-13C right now. The power steering pump really doesn't like cold hydraulic fluid. When I get a warmer day I'll move it next to my shop and try the things Delmer suggests with the top line and check the fill level. Thanks for info and the tips. Greg.
I hope this may help. Perhaps the seals can be cross-referenced.
Thanks Tinkerer, I think I have a copy of that same us military manual. I need to remember to reference it.