JLG 450A problems

[johnbruni]

I have a 1999 450A with a problem on the platform control panel. I replaced the control stick (swing & raise) but I still have a problem once and a while were there will be a loud "click" from the panel and the machine will shut down. If I wait a few minutes (sometimes wiggling some of the switches on the panel) I will hear another "click" and the machine will start up. if I don't hear the click nothing will happen when I try to start it from the basket control.

thanks

jb

 

[VoodooMojo]

A clicking sound loud enough to be heard and will shut down the machine will more than likely be coming from one of the two circuit breakers in this diagram.
After the "click" and everything has shut down, check all terminals of the circuit breakers with a voltmeter (or test light) to see which one is tripping.
They are in the power on and ignition circuits.
If they are tripping, it will be from too much current in a circuit.
We can assist you through the troubleshooting stages if you let us know the outcome of this test.

What engine is in this?

 

[willie59]

I agree, sounds like click of a thermal circuit breaker. Wiggling of switches and controls is coincidence, has nothing to do with breaker re-setting. When a thermal breaker trips, it will make an audible click sound. Likewise, since it a thermal breaker, once the bi-metal contact within the breaker cools, after a few moments, it will once again "click" when it re-sets. You have something tripping that breaker.

 

[johnbruni]

Thank you both for your quick response I will test that as soon as rain stops it is a dual fuel motor

 

[johnbruni]

upon further inspection of the control box I found the following items:

the circut breaker closest to the 7 sec. delay relays is the one that is triping.

I also found rust/corrosion on one side of the contacts on the emergency/red mushroom switch.

Also found rust/corrosion on the relay blocks where the wires connect to the relay terminal blocks.

I guess it would be good to replace all these items to start.

anyone know sources for these items besides JLG?

thanks

jb

 

[VoodooMojo]

any major rental yard in your area may have these parts in stock or will be able to order them for you.
or just google 'jlg parts' for aftermarket parts distributors.

does the circuit breaker tripping thing happen before or after stepping on the footswitch?

 

[VoodooMojo]

JLG had a funky wiring set-up in the FootSwitch.
There were 2 MicroSwitches interwired. One switch supplied Negative and the other switch provided Positive for on-pedal control activation. They were adjustable for simultaneous activation with a set-screw.
If the switch providing Positive activates but the Negative switch doesn't, then the Circuit Breaker will open (hopefully) because of the direct short circuit. No big deal, just be aware...do not eliminate the circuit breaker.

The switches are activated by a spring loaded apparatus that, if adjusted correctly, would provide function lock-out and engine start with the foot pedal not pressed, and provide function power and engine start lock-out when the foot pedal was pressed.

If a switch is not adjusted properly or not operating correctly, it can result in a direct short circuit causing the circuit breaker to trip.

You should hear only one click at these switches when pressing the foot pedal. This would signify that both switches are triggering at the same time.
If you hear two distinct clicks while slowly pressing on the foot pedal this means that one switch is triggering before the other. This will cause the circuit breaker to trip.

Here is a drawing of the switches inside the foot pedal showing the switches with the pedal not pressed:

 

[johnbruni]

well I replaced the two circut breakers, three relays and bases on the din rail that were rusty, along with one contact on the emergency stop that was rusty. Everything seems to function ok, but the function speed knob does not do anything and the functions seem to run a bit slowly. Would i start by replaceing the knob and control under it or that plus the board that controls it?

Thanks to all for all your help this site is awesome!

 

[VoodooMojo]

I would test the potentiometer first.
Attached is a test procedure if you are not familiar with the process.
The resistance change as the potentiometer stem is moved should be smooth and not erratic.
If the potentiometer tests ok, the circuit card may be suspect but before spending the jing on a new circuit card, verify that
the potentiometer tests ok at its connector also.

 

[johnbruni]

seems all of the above problems are solved. Time for a new one. the machine runs but the idle is very rough until you go to shut it down via the platform red kill switch. the machine continues to run for up to 30 seconds but the idle smooths out and runs well until it stops.?

thanks

 

[willie59]

If you're using gasoline and it runs rough, likely caused by this alcohol gas we're using now days. Would it be possible to get your hands on a propane tank and see how it runs on propane?

 

[wisco]

were can i find a parts diagram for a 40h

 

[wisco]

id figure a circuit breaker mine did that too.. not anymore tho. goodlouck

 

[johnbruni]

have a leaky valve assembly under the machine that controls the drive function. It is the one with the two solinoid coils on the side of it. seems to be leaking from the top of the valve (there seems to be three plugs of some sort of there. could it be as simple as a o ring on one of those plugs?

thanks for any help in advance!
jb

 

[willie59]

All of those valve manifolds have various plugs, check valves, solenoid valves, etc, that use an o-ring as a seal. However, it must be a 568-900 series (SAE O-Ring Boss) style o-ring of proper diameter. If you attempt to use other 568-XXX o-rings, they will fail.









Try replacing the o-ring on leaking component first. If it still leaks, and not from failure of new o-ring, look for crack in valve manifold that component threads into, and cracks can be difficult to find in those things.

 

[barklee]

All of those valve manifolds have various plugs, check valves, solenoid valves, etc, that use an o-ring as a seal. However, it must be a 568-900 series (SAE O-Ring Boss) style o-ring of proper diameter. If you attempt to use other 568-XXX o-rings, they will fail.




View attachment 92966




Try replacing the o-ring on leaking component first. If it still leaks, and not from failure of new o-ring, look for crack in valve manifold that component threads into, and cracks can be difficult to find in those things.

Arent those O rings very difficult to get a hold of in a pinch? We had a similar problem last year and had a very difficult time finding them. Do you know of a good source?

 

[willie59]

Arent those O rings very difficult to get a hold of in a pinch? We had a similar problem last year and had a very difficult time finding them. Do you know of a good source?

Not so much their difficult to find barklee, just won't find them at places that don't deal with hydraulic components. If you don't have an o-ring supplier nearby, you can find them on the internet. I use an o-ring boss kit myself, they're out there. And if a person owns a machine that has components that use SAE O-ring Boss fittings, it's a good idea to have one of these kits.

http://www.rtdygert.com/catalog/index.cfm/214/Boss O-Ring Kit

 

[johnbruni]

new issue, when i go to start up the machine rather than the continious beep i get a pulse beep. looked all over in manual but no description.

anyone have a clue?

thanks

jb