Hi Guys. I'm troubleshooting this lift for my boss. Hydro Mech is not my area of expertise. It's an old lift, and the swing drifts a lot. It has a swing break that doesn't seem to engage under any conditions. It did engage once this morning, however, but I'm not sure what we did to make it do so and I haven't been able to make it do so again. It looks like a single caliper with two pistons that bites a rotor which is part of the swing gear assembly. The caliper appears to have one hydro line going to it. Can someone tell me when a swing drive is supposed to engage? Is there a switch or solenoid that engages it? JLG does not have a manual for this lift online. Any ideas on what the possible points of failure might be? Thanks so much, Matt.
Hey Matt, iam having the same issue with my Grove, didnt know it might have a swing brake. Mine is a 92 model but after releasing the left or right it still drifts about 8" or more. I have no idea how it works so iam not any help to you but if you figure it out please post back and let us know if you dont care.
Old White Man, No response yet, but here's where I am in light of general research--on this lift the swing break is engaged by the hydraulic system--some are spring or even electric. The basic idea as I understand it is that the break should be on any time the arm is not swinging. It also runs on the pilot system, which, as far as I can tell, has a separate pump coming off of the main pump and is basically a low volume pump system delivering fluid to various places. For the swing break, there is a joiner box where hoses from the swing controls and the pilot system to the brake meet up. It looks like when fluid is sent to swing it somehow is supposed let off pressure to the swing break. My problem is that pressure isn't there in the first place. Finally, if I lift the boom a bit, and then wait five minutes, the brake will finally engage, it seems from a little bit of bleed off pressure from a boom that sags a bit. Hopefully an expert will take a look and either correct or confirm what I'm saying here. I'll keep you posted, but I'm thinking this forum is my last hope short of living with the swing drift. Matt
Welcome to HEF redheaddiesel. I don't have info on the 33HA myself, but I wager it's not all that different than a 34HA or a 40HA. On those machines the swing brake is spring applied and takes hydraulic pressure applied to an internal piston to overcome the springs and release the brake. This pressure comes from the two hoses that connect to the swing motor. The oil from those two hoses is routed through a shuttle valve, looks like a Tee connection between those two hoses. When you operate the swing, CW or CCW, the oil from those two hose goes through the shuttle valve to apply pressure to release the brake, as soon as you stop swing operation, pressure goes away and springs apply the brake. JLG machines of that vintage typically used a MICO brand swing brake. It's not uncommon for them to suffer from broken springs or moisture inside the swing brake unit causing rust/corrosion which affects movement of internal components which includes causing the piston to seize. I've rebuilt a number of those MICO units in the past, should be able to get the rebuild kit from JLG.
thx redhead, and it appears ours work similar. Looks like our choices are to tear into it or leave it alone as you say "just live with it." Without a breakdown Iam a little nervous on tearing it apart seeing as parts for a grove are through the roof from minpar, but yours on the other hand are probably ready available. and since your getting paid for learning, i would go for it.
Thanks for this info, Willie. From what I can tell this one is different. The caliper rides on two pins and when not engaged it simply floats. It has one hydro hose going to it which applies the break with pressure. This one hose is connected to the pilot system and also to a box that may be a shuttle valve--it's a flat box which has six lines: to control right, to control left, to motor right, to motor left, and two to the pilot system. For some reason, pressure never gets to the caliper unless you lift the boom and wait....then the back pressure from it dropping seems to engage the swing break over a few minutes.
I don't know what they're doing with that setup, not familiar with it, but I would be shocked if they're using hydraulic pressure to "apply" the swing brake, that's unheard of, if that's the case the swing could drift when the engine is shut off and pressure goes away. But then, I really don't have a clue. Could you post some pics of this apparatus?