JLG 40HA questions, boom will not raise/lower, and some other questions

[dwhite22285]

A friend and I are buying a 1995 JLG 40HA with the Deutz Diesel engine, I need it to put up a steel building on my property, and he needs it to do some work on the outside of his house. We are paying $1,000 for it so it is worth more than that just to haul off as scrap. I am hoping to trade it off to a guy for a skid-steer once we are done with it.

What I know:
It had been sitting for 5-7 years, I put a new battery in it and it fired up without issue, I think it is locked on hi-idle though as it seems to be idling pretty high, I am guessing low idle was bypassed because it caused issues or something, or maybe the idle selector stopped working. I am not real concerned with this and should be able to fix it or leave it as-is.

It would not go in forward when we started working on it, I found a broken wire at the drive pump and now forward works.
4x4 SUCKS, it only spins one tire if it is in any sort of mud (it was in ALOT of mud, took us 3 hours to get it out)

Our MAIN problem is the tower/upright cylinders don't function properly.

Upright cylinder has not moved at all since we have started working with it, the tower cylinder went up but will not come down. We are wanting to get this thing on a trailer to get it home so it is not sitting in the guy's parking lot, but with the tower up it makes it pretty tall and we are worried about power lines, plus, it won't go into hi gear.

How can I get the tower to come down, and is there a reason the upright cylinder might not be extending?

Thanks for the help!

 

[willie59]

Welcome to HEF dwhite22285. :drinkup


The tower boom has a boom extend as well, if that tower boom is extended any at all the tower boom will not lower, the extension has to be fully retracted. If it still won't come down, it could be a problem with the selector valve located on the tower boom. When tower boom retracts, it contacts this selector valve to allow tower lowering. Look on the bottom side of tower boom, where the extension section comes out and you'll see that valve.

 

[dwhite22285]

Welcome to HEF dwhite22285. :drinkup


The tower boom has a boom extend as well, if that tower boom is extended any at all the tower boom will not lower, the extension has to be fully retracted. If it still won't come down, it could be a problem with the selector valve located on the tower boom. When tower boom retracts, it contacts this selector valve to allow tower lowering. Look on the bottom side of tower boom, where the extension section comes out and you'll see that valve.

This unit does not have an extension on the tower boom section, only on the main boom. It will not extend the Upright cylinder at all either.

(Hydraulic fluid is full)

Thanks for the help

 

[willie59]

Sorry about that dwhite, I got confused with the 60HA which has tower extension. Just to make certain we are on the same page, the tower cylinder raises/lowers the tower boom, the upright cylinder keeps the upright frame vertical as tower boom raises/lowers, and the main lift cylinder raises/lowers upper main boom.

There is no normal control for the upright cylinder, it's controlled by oil from tower cylinder operation, does it's thing as you raise/lower tower boom. However, if I recall correctly, there is a manual valve to "adjust" upright if it gets out of whack, as in "not vertical". I don't recall where the valve is located or what controls it, should be covered in the operators manual.

As for tower went up and won't come down, any number of things could cause this, be hard for us to say exactly what problem is, it's going to take some electrical testing on your end to begin with, testing voltage output of toggle switch at lower controls and see if these outputs are getting to control valve for tower operation. Just to be certain, don't mess with the holding valve cartridges on the tower lift cylinder while that boom is up.

As for idle speed on Deutz engine, they're not set at a "low" idle speed. Low engine is set at 2200 rpm, High engine is set at 2800 rpm. Additionally, if tower or main boom is raised it won't engage high engine speed.

 

[dwhite22285]

The Upright cylinder never moved when I raised the tower, it stayed fully collapsed. The tower cylinder is fully extended but will not retract. The solenoid appears to be working, the hoses tighten/release when toggling the switch up/down. It almost seems like it is not getting enough pressure but I am not sure if that would cause it to not come down (and for the upright to not extend).

Our #1 priority is to get the machine to our shop to keep from having to drive back/forth to work on it. To do that we need to get the tower down so we are not taking down power lines

Thanks for the help

 

[willie59]

Ok, you've got an interesting delima, I'll have to give this one some thought. But you still need to check you're electrical output at ground control switch, see if you sending out a voltage signal to lower tower, and test wire at control valve to see if it's getting voltage to activate valve to lower tower.

 

[dwhite22285]

The solenoid energizes (magnetizes) on the left side for up, on the right side for down, so yes, the switch works.

 

[willie59]

Does it load the engine when you select "tower down"?

You could have a problem with the control valve. Since it went up, confirms the up coil works, you could switch the hose connections at the control valve, then when you select "tower up", see if it comes down.

 

[dwhite22285]

We tried switching hoses, I think I picked the right ones to switch but since it has two hoses on each end of each cylinder I am not 100% sure I got the right ones. But no, it did not make the tower come down.

The more I mess with it the more I think it is lack of pressure. Can I just put a gauge on it there at the quick connect at the pump?

 

[willie59]

No, don't mess with the hoses at the cylinders, switch the hoses at the control valve for tower up/down.

 

[dwhite22285]

That's what we switched. Just meant that I traced the hoses I thought I should switch back from the cylinder. Should I literally just swap the hose coming off the solenoid block and not worry about where they go? Should I swap all four hoses or just the two main hoses? Thanks

 

[willie59]

Well, I don't want to steer you wrong, but this is actually quite simple. If, in fact, the main control valve (tower up/down solenoid valve) made the tower go up, but not come down, forget about all the hoses running to the cylinders, gets way too complex, simply switch the hoses at the up/down solenoid valve, you should be able to bring the tower down by selecting "tower raise". If it doesn't work, you either have a problem with someone has switched up some hose connections, or you have a problem with a holding valve cartridge on the tower cylinder. I certainly hope you get this thing figured out.

 

[dwhite22285]

http://forums.hydraulicspneumatics.com/eve/forums/a/tpc/f/8621030121/m/5927052036

I think that is the problem I have, I thought I mentioned it, but guess I didn't. I had to replace one of the hoses, it would spray when trying to lower the tower. I am going to switch hoses from one end of the upright cylinder to the other, so hopefully it will try and raise the upright when I lower the tower. Then switch them back once it is down.

We did get it hauled home, had to put PVC pipe on the boom to make power lines slide up and over, only hit a couple low hanging lines (telephone, not actual power lines). It was a short trip and we did it