As several of you have noticed already, I'm new to the forum so I'm sorry if this question has been asked before but I did some searching and didn't find anything. I'm a farmer and I recently purchased a JLG 50HT boom lift to do some work on top of grain bins, replacing tall pole lights, working on crib roofs, etc. Most of this will be done on my home farm but occasionally I might want to move the lift to another location (maximum of 5 miles away...usually more like 2 miles). The problem is I really don't have a good trailer the haul it on and I'd really rather not drive it that far (although i've probably done stranger things). My question is this, is there any way to dissengage the drive wheels and brakes so that it could be towed? I know the manual says a stock unit is not designed to be towed but I'm wondering if it's possible every once in a while. when I was shopping around I remember seeing one a guy had a tow bar for that he just hooked it up and pulled it around (i forget which model it was though but it was a normal gas engine boom lift, not one of the pull behind your truck ones). anyway it seems like there are some people here who really know what they're talking about concerning these kind of machines and this is my first time poking around with one so I figured I should probably seek out someone who knows what they're talking about rather that poking around myself and possibly end up screwing something up. thanks
On the end of your drive hubs, there is a little plate with a nub sticking out of it held on with two 1/4" bolts (7/16 head). Take the plate off, turn it over and reinstall with the nub inward. That disenages your hubs. Now what about steering it? Some machines have a push/pull valve with a black handle under the hood made to let the steering "float". Look for one of those. Quick & dirty solution, "Tee" into the two steering hoses right close to the cylinder, run a by-pass hose between them with a valve in the middle. With the valve open the steering will float, with it closed it's business as usual.
Thanks OFF, that gives me something to look into now. I'll have to look at the steering to see what I do with that.
Hey OFF, I have to remind you the steer cylinder won't float completely if all you do is provide a bypass hose with valve between the two steer cylinder lines. The cylinder might extend fully, but won't retract fully because of displacement difference between rod side of cylinder piston and barrel side of piston. In order for the cylinder to float correctly, you have to connect (with some kind of valving) the two steer lines to the case drain line of the drive motors which is a tank line. This allows fluid to move back and forth and account for the displacement difference. Then there is still the problem with connecting a tow bar. Not sure how to do that. The JLG option leaves the steer cylinder in place, tie rod to opposite wheel in place, but adds an additional tie rod from that wheel to a tow bar pivot plate in center of axle. Then there's the problem with roading, I don't remember the top speed you can tow these machines, but I'm near certain it's a slow speed. When you disconnect the drives with the little nub plate, your simply disconnecting the drive hub from the motor/brake assy so it will free wheel, but you still turning the planetary gears in the torque hub. Not sure how fast we want those planetary gears turning. I'm more inclined to just drive the machine. When you have them in hi range and hi throttle they move at a pretty good clip.
Good points Atco. All that's doing in taking the brakes off, you'd want to be carefull not to overspeed. Trailer is the way to go if you can. A work, we used to tow the 40F's & 60F's before we got a trailer (large site, miles across) but always nice & slow.
A heavy duty version of a car dolly would solve all the problems
LoL, I was thinking the same thing. It would have to be a real heavy duty version. The HT model is a zero turning radius counterweight, so they have to be heavy since the counterweight does not have a great deal of offset from center of rotation. The 50HT weighs right around 23,000 lbs. Also, about 25' long, better not have to make some tight turns. The width is 6' 6", not a whole lot of room outside of that to have dolley wheels and stay within 8'. But it would be interesting to see one being dragged on a dolley.
hey guys, a couple other quick questions. I was playing around with the lift for the first real time today and a couple things popped out at me. when I rotate the boom it jerks pretty good starting and stopping. nice and smooth when it's actually moving though. previous owners had just put in a new switch for that control before I bought it. could it just be a new switch that needs to "break in" a little or is it possibly the wrong switch? I just can't feather it like I can raising and lowering the boom. maybe related, I don't think the high/low engine speed switch is doing it's job. when I flip the switch i notice no difference at all. I would think the engine would change rpm, is that correct? speed of different functions is not affected in any way and there is no change in rpm. (this is all with the boom below horizontal) I checked the switch with a multimeter and it appears to be fine. could there be a problem in the wiring or maybe is the switch that is supposed to lock out the high engine speed when the boom is over horizontal not functioning right? any ideas?
First thing we need to know is what type of control does your swing have, is it toggle switch or is it proportional control lever? If it's a proportional control, is it a PQ controller which has a large body on the control panel, or is it an OEM controller which is basically just a lever sticking out of the control panel? The engine speed on your machine should only operate when you work the drive function. The engine speed doesn't change for boom operations.
based on your description I would say it's a PQ controller. it has a black body with a lever coming out of it. you have to pull a release on the lever to move it (locks into place on center position)
Yep, the PQ controller is a black housing mounted on the face of the upper contol panel, the lever is on the side of the housing and has the locking notch. The PQ is properly adjusted with an oscilloscope (like, who has one of those in their tool cabinet?). There is a procedure to adjust without one, but I've never met much success using it. But since it's not working properly, try this. Open your upper control panel and remove the mounting screws for the controller so you can pull it away from the panel, there should be enough harness to do this. If not, you probably have the plug in type harness so you can unplug the wiring and pull it free from the hole in the control panel, then plug it back into the controller so you can make adjustment without fighting the panel. You should see 4 adjusting screws on trim pots labled Lo Range, Hi Range, Threshold (or Mid Range), and Ramp. With a small screwdriver, back out (screw CCW) all trim pots. You may have to scrape away a coating on the screw heads that prevent them from turning. These are 32 turn trim pots, meaning, after they have made 32 revs they are at the end of their adjustment. As your turning them, you want to listen for a very faint "click click" as your turning. That's indicating it's at the end of the adjustment. You have to be in a quite place to hear the clicks. Now your ready to adjust. Engine running, foot on footswitch, creep switch in "creep off" position. Unlatch lever and move it to the point where the side of the locking notch is lined up with the side of the notch in the housing, like two lines meeting. This is notch out. Hold the lever there and adjust (CW) the Lo Range trim until the boom just starts to move. Move the lever to full throw. Adjust the Hi Range trim until the boom moves at the desired full speed. You will need sufficient room for boom to rotate around to do this. Also note that as your turning the screw in, the boom will pick up speed, but it will reach a speed that is max and no more. Don't turn the adjusting screw far beyond that speed point as it doesn't achieve anything and can affect the other speeds. Now adjust your creep speed. This should be a very low speed. The creep is useful when you have the boom in the fully extended range and rapid movement isn't desired. Right now your probably working with boom fully retracted so just keep in mind you have to guess what a slow speed is. Or, you could extend the boom and have a better judge of what a proper creep speed is. Set the creep toggle to the "creep on" position. Move control lever to full throw. Adjust Threshold (Mid Range) until the boom moves at the desired creep speed. Lastly is the Ramp adjustment. The ramp is the length of delay to stop boom from moving. Have the boom fully retracted to do this. To get a feel of "no ramp" (have feet firmly planted), step on the foot switch, move the lever to full throw, then just release the lever so it rapidly returns to center. You'll notice the abrupt stopping of the swing. The ramp will provide a slow down for this motion and will adjust how short or long the slow down is. I think you can turn the screw in at least 10 turns to achieve a pre-set to begin adjusting. Swing the machine again and release lever. Still abrupt stop? Turn the screw 5 more turns. Swing and release. At some point you'll notice the swing slow to a stop instead of abrupt stop. Once you find that, adjust in or out to achieve your desired ramp speed. I all this doesn't work out, we'll figure out a plan B. And I wonder if OFF knows a different method of adjusting PQ controllers? Let us know how this works.
I adjust them almost word for word the same as you do Atco. :thumbsup I used to adjust them using an old style analog multi meter (sweep needle) and jumper harness I made that goes inline where the controller plugs in the harness, following that 6 page procedure you mentioned. But I gave up on that once I learned the feel of what those little screws each did. Now it's all by feel.
Darn it! Well, so much for hoping someone has a better method than the way I do it. :tong PQ controllers are a trick to adjust, I'd much rather adjust OEM controllers because you can do them with a volt meter.