I need help with a Hyster Forklift. Is there a section on this forum or can someone point me to a forum that could help? Trying to find out year, make, model of a Hyster and I also have a problem with it. The lifting ram has a hard time coming down, it is newly rebuilt. I followed the two lines from the ram back to a block on the right side of the frame. I wanted to know what that was and could it be causing the forks to have a hard time coming down?
Looks like an H60C or an H80C (6000 or 8000 lb cap.) to me. Raise the hood and look along the top of the frame for the serial number. Should be an alpha numeric such as D6D1234, with that I can tell the year. Does it have a 6 cylinder flat head Continental engine? The valve that you are showing is a 2 speed valve, it combines the flow from the top of the cylinder with the in flow from the pump to make raising faster under light loads. More pictures of the cylinder and piping would confirm this.
Just a thought...... The lift cylinder on a forklift is "single acting". In other words, it's under pressure when it lifts but it relys on the weight of the mast & carriage to bring it down. Anything binding or tight or rusty in that whole assembly could cause the problem.
If it's not binding as OFF suggested, another thing to look at, most all vertical mast forklifts have a velocity fuse in the cylinder line to control drop speed if hose was to fail. A malfunctioning velocity fuse will slow the rate the mast/carriage comes down.
Alright, I have these numbers stamped on a plate under the dash on the right side. C5D 5858 K I have not had a chance to go check the frame for other numbers. The machine is equipped with a flat head 6 cyl. There is nothing binding, tight or rusty that I can see holding up the forks. It worked flawlessly up and down previous to me having the ram rebuilt, it just dumped oil out the top of the ram when ever you tried to lift something. the velocity fuse sounds like a direction for me to check where would that be located? Also, take a look at this photo. note the white arrow. There is a 1/4in npt pop valve of some sort, what is it. oil is now coming out from there to. What is that. Thanks for the great replies!
A more accurate description of what is happening. the lifting forks go up just fine. they get stuck on the way down with out weight. you have to jump on them or add weight to get them down. during that action, hydraulic oil comes out from that 1/4" npt poppet valve at the top of the ram. I have also noticed that the hydraulic oil was pretty ugly before rebuilding the ram, it does have new hydraulic oil now in the reservoir, but it is super clean, I know there has to be some of the ugly oil left in the system, but yet when I check the dip stick, it is clean oil, almost like the system is not circulating?
In theory......if the hydraulic filter was on the return line to the tank, and it was plugged up badly.....it could stop or hamper the mast from coming down. The other functions which are "powered" would "by-pass" or force the filter. I've never seen it, but it is possible. That vent at the top of the cylinder should not have oil coming out of it under normal conditions, however anything that gets past the seals on the lift cylinder piston will come out there. On newer machines that vent is connected back to the tank with a low pressure tube. As AtcoEquip mentioned, there's a safety valve at the base of the mast cylinder. It's purpose is to prevent a sudden free-fall should the hose fail between the cylinder & control valve. That could very well be sticking as well. Very small orifices in there. When hydraulic oil is allowed to get to the ugly stage, things start going wrong.:beatsme
First off the serial number indicates the machine was built in 1966. The little plug is a bleeder for the lift cylinder. You mention that the cylinder was repacked. After installation was the air bled from this plug? This is necessary for the valve in your first posting to work correctly. This cylinder will have oil on both ends under operating conditions. At the base of the ram in the piston there is an internal valve, was this checked and cleaned when the cylinder was apart? It is not unusual for these valves to plug with particles from the packings when they disintegrate. This valve along with the valve in the picture need to be operational in order for the cylinder to work properly. What i would do to trouble shoot this problem is first isolate the problem. Did the ram slide smoothly in the total length of the bore when assembled? If yes then mechanical binding can be eliminated as a cause, if no then you need to determine the cause of interference (a dimple in a lift cylinder is not unusual) before we can go any further. The simplest way to troubleshoot this would be to first bleed all air from the bleeder. Loosen the bleeder and SLOWLY at idle pull back on the lift lever until all air is gone or the cylinder reaches full extension. After you have done this stroke the cylinder a couple times and see if operation improves. If not then lower the cylinder and disconnect the steel line at the top. Attach a hose (any low pressure hose will work) to both the steel line and the fitting on the cylinder and run them into a 5 gallon pail. Operate the cylinder and watch the two hoses, you should see some oil from the cylinder and possibly a slight trickle from the steel line but very little. If you see a large flow from the steel line then the external valve has a stuck poppet. If you see a lot of flow from the cylinder line then the ram valve is leaking or stuck. Try these tests, one should give us a hint as to your problem.
The air was not bled from the ram. Where is the air bleed? is it that 1/4" poppet valve at the top that I am pointing at? I will try everything suggested to troubleshoot the problem. Thank you for all the great info.
Yes the bleeder is the one at the top, reseal with teflon tape or any good thread sealer (not locking just sealing).
I should have mentioned, is the bleeder the original two piece bleeder or a plug? If it's two piece it should seal when tightened and not need sealer, if it's just a plug then it will need to be sealed.
This is what I pulled out from the top of the ram. When I bleed the air, do I leave this tight because it has a built in valve or do I still loosen it up?
No wonder it leaks, that is a grease pressure relief vent. It is designed to control pressure in a grease cavity (bearing, bushing etc.) to prevent pressure from blowing out a seal or getting in somewhere it is not wanted. These are generally designed for about 1-25 psi, not hydraulic pressure in a cylinder. You need just a plain pipe plug or a 1/4 turn bleeder. A pipe plug is a little more difficult because you are depending on the area around the threads as a bleed path. But as this is not an everyday usage a pipe plug is fine.
Learning a lot here! Okay, now I know what you mean by a 1/4 turn bleeder. I will pick one up, I agree, it will be easier then depending on the threads to bleed off. Thanks.
Fella's, I'm not convinced about all this. Something is not making sense to me. First of all, the pic shows a rather large and heavy duty pipe going to near the top of the cylinder. That has to be the pressure line to extend cylinder. It's too large and H-D for a vent to tank line. Also, if it were a vent line, then the curious fitting at the top wouldn't be leaking. So, if it's the pressure line, and it's on the top of the cylinder, this would make the cylinder self-purging of air the first time you raise it and lower it because an air bubble would go directly to the top. As soon as you retract the cylinder, the bubble would go out the line to tank. Second, the curious fitting is near the very very end of the cylinder. It is so close to the end of the cylinder that I can't imagine there's room for any type of pressure seal above where it's located. I'm thinking the pressure seal is below where that fitting is, therefore, no fluid should even be where that fitting is. If there is anything above the level of that fitting, it would be a wiper seal. I think it's possible that cylinder has Vee packing held in by an internal gland ring. The Vee packing would be in the area between the pressure line fitting and the leaking fitting being discussed. I'm thinking that special fitting is correct, it's a vent fitting to release leakage and not blow the wiper seal. It's an indicator fitting, indicating there's a problem with the Vee packing not sealing proper. The problem with this, redline said the cylinder has just been rebuilt. Hmmm, something just not making sense to me here. Sorry to muddy the water redline, but something just doesn't look right here to me and I thought I would point this out in case you got a improper rebuild job.
Atco, Nobody said it was a vent line (at least not me), this is a pressure line just like the one at the base of the cylinder except it does a different job. This is a two speed system and both sides of the piston are pressurized although not like most people would recognize.There needs to be a bleeder at the top to purge air whenever the system is open, The fitting at the base of the cylinder goes to the control valve and is the main lift line, the one on the top goes to the valve in the first set of pictures. The cylinder is set up as a quasi regenerative hydraulic circuit, lending extra flow and faster lift times during times of lighter loads. During heavier loads the oil on top of the cylinder is sent back to the reservoir. This is not your typical lift truck lift cylinder system, as a matter of fact Hyster also does it today on their larger lifts although it is now done with electric solenoid valves. I have repaired many of these through the years, a lot of them after someone else had been there.
Wow, that's a cool cylinder set up they have BillG, I like that! I haven't worked on one of those cylinders, but have worked on numerous Hyster forklifts and they make a darn good forklift. Some models were built like an anvil.
I know, I wished the guy lived a little closer. I'd talk him out of it somehow, those H models of this era were in my estimation probably the best lumber yard, brick yard, steel yard or any other yard forklifts of this size ever built.
I used to work on a hyster for a customer that had all the ID plates missing, don't remember the model. It was an older model, very heavy lifter, but compact in size (compared to newer machines of same capacity). It was a heavy little bugger. Along with the counterweight, it had steel ingots along the inside of the frame. More than one wood floor trailer had the rear wheels break through their floor hauling it. Everything about that machine was heavy, and it would lift the world if it could get the forks under it.
Ya know, that was such a common practice years ago. I don't believe many of the lift trucks built today would stand up to this practice. I had one customer that had a 105,000lb Taylor and some knucklehead told them that the 105 was the same as the 120. Well they decided to add counterweight to it so they could do a job a little faster. The problem was that the 105 had no place to add counterweight in the back because of radiator air movement. Well this didn't stop them, there was plenty of room along the inside of the frame. Until some repairs were necessary and I had to pull the engine because I couldn't get the blower off (Detroit). Live and learn.
Alright, I was able to go out and work on the machine today. I did as told and installed a 1/8 bleed valve, I started up the machine, I opened the bleeder and slowly raised the forks, very little air came out then a few drops of fluid came out. I only went up maybe 4ft. then closed the bleeder and back down, did the same procedure again, opened bleeder, raised forks, very little air then a few drops of fluid. then I tried going faster with the hydraulics, same, nothing comes out, then I just took the bleeder out, now its just open threads, same, very little air, just a little psssst and a few drops of fluid. so I put back the bleeder, lowered the ram, opened it back up, then raised the forks all the way up. yep, stuck. the forks would not come back down. I almost had to call back to the yard and have my excavator delivered, but instead I used a long ratchet strap to pull it down as I pushed on the lever to lower it. while we were ratcheting the forks down, I noticed that the lower fork roller was not rolling and was binding on the guide rail, all I had was WD40, so I soaked the wheel and guide rails and started at the bottom, working the forks up and down as I worked up higher. It is a lot better and lowering on its own now. so tomorrow I am going to grease them up real good and see if that takes care of it. I hope all it is was a stuck roller. will see.