Good Morning Forum Users, First time poster here. I have a 2012 Z45/25J electric Man lift a secondary boom lowering problem. First off let me indicate that all other functions and controls appear to working as advertised for the man lift except the secondary boom lowering. If the speed control is set to 5 or faster, there is no apparent problem, but it could just not be as noticeable due to the speed at which the secondary boom lowers. When set to 4 or below, lowering the secondary boom causes the boom to stutter, when in the basket it feels as if you are in a shaker machine of some time. The hydraulic rams on the secondary boom are about 30 inches; during testing, I notice this problem occurs with the ram extended about 15 inches. Any lower than that; you can lower the secondary boom without incident. If you go higher than that, the secondary boom begins to stutter during lowering. If you continue the downward travel while stuttering, the stuttering stops when there is about ¼ of the ram extended. During the lowering process if it starts to stutter and there is less than 15 inches of the ram extended, you can raise the boom a little and start lowering again without incident. Although I did not think it was the problem, I swapped a couple function solenoid valves around to see if there was any change; there was not. Since every other function on the man lift works great, I do not believe it to be a hydraulic pressure issue. I am thinking something with one of the hydraulic rams? Any help or suggestions would be much appreciated. Richard
Update Update. I checked the Boom Function Speed Controller Adjustments to see if that is the issue, just to eliminate it as a suspect; no problems found. Since the lower control panel has no way to control speed via a rheostat, I have disconnected the wire connected to the Proportional solenoid valve in order to manually put the unit into creep mode. I did this so I do not need anyone in the basket at the controls to make it stutter on the way down. All the bouncing is not very nice when you are the one in the air. I really did not feel the flow control valve and coil for the secondary boom down had anything to do with the problem, but I swapped it out with the primary boom down (same valves and coils) with no change in the way the unit reacts and the primary boom works perfectly as before with the secondary boom's valves. The unit stutters the same way via the primary hydraulic pump and the backup hydraulic pump. When looking at the hydraulic rams as it stutters, you can actually see the rams flex outward because of the stress on them. Unfortunately, I have no way to check the hydraulic pressure at the moment because of the apache valve that is used on the test port. I am going to go by John Deere today, hopefully I can buy a female fitting to attach a gauge to check pressure with. I have read about locks in the hydraulic rams themselves, could one of these locks be not releasing properly? Maybe not enough pressure to it? I'm not really sure how they work. Richard
Another update. Well, I was able to find a female quick disconnect fitting on the way home yesterday. Connected it to the system. The book states pressure relief for the secondary boom down pressure should be set at 2100; which it does. Now, when I use creep mode lowering the boom above the half way raised position and the unit starts to stutter (bounce badly). The hydraulic pressure varies from about 475 to 550. When the boom stops stuttering (below the half way raised position) the pressure settles out at 500. I believe this variance in pressure is a result of the boom just bouncing. So I feel the hydraulic pressure is not the culprit in this situation. Would anyone agree with me? I am really leaning towards there being something faulty with the hydraulic ram that appears to be bowing out during the shake. :Banghead Richard
I've made a little video if anyone would like to view it and has any suggestions. https://youtu.be/Xzxgu_hP8Ek
A few things that I have seen that can cause a problem like this. You have already covered the valves as a possibility (although they can still be troublesome). The next thing I would check would be air in one of the cylinders trapped below the piston, on a slow acting cylinder with the right geometry air can do some strange things, and can be difficult to get out without disconnecting it and arranging in such a way so the air travels to the fitting. The last thing would be either a cylinder tube that is distorted in the area where the problem exists, or a bent rod on either of the cylinders causing the piston packings to distort, although it should cause this problem through the complete stroke. I couldn't see the cylinders all that well in the video so you will have to inspect them up close.
Bill, First off let me thank you for the response and assistance. I collapsed both cylinders today and bled the cylinders for some time today ensuring there was no air trapped in the system. I tested the unit again with no change. Even though I had the proportional valve coil unplugged, I removed the coil and the valve itself was corroded a good bit; so we removed the corrosion off of it and reinstalled the coil. I notice that when I have the secondary boom in the raised position and lower it, I can reproduce the exact problem by quickly sliding the coil on and off slightly even at the point where it normally does not stutter. So, now I feel that the problem is the proportional valve itself; I pulled it out and looked at all the O-rings and scarf-cut seals and they appeared to be in good working order. My thought is this, something in the proportional valve is amiss and the reason you don’t notice it with the primary boom function is that there is so much more weight when operating the secondary boom. Does that sound like a plausible theory? This is when I wish I had a second unit here so I could swap it out with a known good one. But, the electrical system does not appear to be at fault, after all, it does it with the proportional valve completed disconnected. The secondary boom lowering valve was swapped out with a known functioning valve and the problem persisted. The cylinders and manifold were bled ensuring no air was in the system. There is a five volt variance at the proportional valve coil between creep mode and the fastest setting. So, considering the troubleshooting steps I’ve completed, would you replace the proportional valve as well? Richard
Have you tried lubing all the pivot points in the arms? I'm not saying this is the problem sounds a bit more in depth, but I've had a few of the smaller z34 pins in the knuckle get worn after 1-2 years working near sea water and the pins corroding and wearing out the synthetic bushes, causing a shuddering on the down function but not the up. Once the units got back to the work shop we replaced bushes and polished pins
Plant_mech, Thank you for responding. I really did not feel as if this pivot points were an issue; so I did not check them. But, since we are near the ocean, why not, though I did not remove them; I removed the bolt and holding rod for each pivot pin and turned each pin 360 degrees with what I would consider little resistance. I would think that eliminates them from the equation? The shuddering is only the secondary boom rams are extended half way or more. Richard
On the old S85 Genies, we used to add Seafoam Power Steering & Hydraulic System additive to the hydraulic oil to stop a similar boom chattering problem. Might be worth a try. We used a couple cans, and took a while to work its way in there. It wasn't instant, but it always worked.