jlg 40HA manlift

[eianewb]

anyone out there have any experience with one of these? i seem to be having a couple minor (i hope) electical problems with mine. one i fixed for $13, gatta like fixes like that. i had a broken wire somewhere between the basket and the ground controls... 13 dolla extension cord fixed that.

now i seem to be having something with the valving wrong. i dont know what exactly, but the engine keeps bogging down like it is working hard and i am not doing anything at all with it. i then go to move anything at all (not the drive) and the bogging dissapears and it functions just fine. i know it is not the valving itself because when you go to shut the machine off there is a couple seconds there where the electrical system is shut off, but before the engine dies that the bogging goes away.

any thoughts??

thanks

 

[willie59]

Wow, this is a tricky one for a forum thread. The 40HA is one model I haven't done much work on. Please avoid operating the machine until you get this fixed, you will destroy your pump. I'm working on a 110HX right now that killed one section of a 3 stage Parker pump doing this same thing. There can be a number of causes for this, electrical or valve problem, and it's not going to be easy for me to tell you what to look for. Your problem is with what we call a dump valve, either energized or stuck. The 40HA used one of two valve configurations; electric valve controls or hyd valve controls, and these two use different dump valve arrangements. This is pretty easy; if you have wiring going to the control valves, then you have electric controls and this is the most common arrangement. Assuming you have electric valve controls, it will have a flow control valve that is the main dump valve and a dump valve on the valve body for steering, basket level, basket tilt, and basket rotate. JLG calls this valve body the bang-bang valves. The flow control/dump valve is in the pump pressure line. Follow the line that leaves the pump and you should encounter a Tee fitting. This Tee feeds oil to the control valves on one line and the other line goes to the flow control/dump valve. The first thing I'd do is disconnect the electrical connections to the flow control/dump valve and the bang-bang valve section. You can identify the dump valve on the bang-bang valve section by looking for a single solenoid valve on a section of the valve assembly. All other valves of the assembly have two solenoids opposing each other. If you disconnect the wiring to the two dump valves and you problem goes away, you have something powering one of the two, or both, dump valves. If the problem does not go away, you probably have a problem with one of the dump valves. Be patient, this one is going to take some time to figure out.

 

[eianewb]

yeah, they are the bang bang controls.

the funny thing about it is that it started working just fine at the end of the day yesterday, but if it starts acting up again i will sure check out the dump valve.

thanks

 

[willie59]

Oh you for sure have a problem with one of your dump valves, it's just the question is...what's causing it. JLG builds these hyd circuits with a positive displacement pump (gear pump) and closed center hyd control valves. Since the pump is producing oil flow whenever the engine is running, and the control valves are hyd dead ends, they relieve the flow of oil to the valves by using dump valves that simply "dump the oil back to tank". When you engage a function, say steering, on the bang bang valve, you're doing two things; you 1) power up the dump valve solenoind to close the dump circuit and deliver oil into the steering valve, and you 2) power up the solenoid for the steering circuit selected to deliver oil the the steer cylinder. As soon as you let go of the steer switch, steering valve centers and dump valve opens to again return oil to tank.

 

[eianewb]

do you think it could be a bad ground somewhere? seems like 90% of the time you have an elec prob it is a grounding issue.

do you know... is there a difference in the drive and any other (say the main lift) valve, in the valves themselves? meaning... the drive valve is proportional, not bang bang, but is there a way using the existing valves and adding the prop control to make the main lift proportional as well? hopefully i didn't confuse the heck out of ya. lol. just wondering, i am not a big fan of the bang bang controls.

thanks.

 

[willie59]

I'm busy writing...don't go anywhere.

 

[willie59]

I've been studying the parts manual from the JLG website for the last two days. You've established that you have bang valve controls, that helps narrow things down. From what I'm seeing in the parts manual, the drive is contolled by a Sunstrand hydrostat pump contolled by a controller at the platform, probably a P-Q controller. This makes the drive totally independant of all of the boom functions (bang valve functions), but, can also be a source of your engine loading. If the Sunstrand pump does not maintain "null" when the drive isn't being used, it will load the engine because the brake is engaged. This is a rare problem, though. I'm still leaning to a dump valve problem. Somewhere on the dump valve pressure supply circuit there should be a quick connect fitting to connect a pressure gauge. You need to connect to that port with a 5000 lb gauge so you can monitor what the bang valve dump valve circuit is doing. When the engine is running, and no bang functions are being operated, there should be minimal pressure on the gauge. If you hear the motor loaded when no functions are being used, check the gauge, if it shows pressure (oh man, somewhere around 2,300?), then we know the dump valve is not dumping oil to tank and is the source of your problem. If you hear the motor loaded, and there's minimal pressure on the gauge, then you have a problem with the Sunstrand pump not staying in Null. Check this out and we'll go from there. As for making the bang functions a little more friendly to work with, I haven't done that before, but I'm sure it could be done by adding some form of proportional flow control in the bang valve supply circuit. Terex and Genie lifts use these kind of controls to control function speed of bang valves. It involves a rheostat controller at the platform to vary the voltage to the proportional flow control thereby controlling how fast a bang valve function operates. You would have to have an extra wire (wire not being used) in the cable going from platform to ground controls to rig this up. Like I said, I haven't done this before on these machines, but I'm sure it could be done.

 

[eianewb]

atco, so you obviously are a mechanic, what do you primarily work on? i read on some other post that you would just go get a jlg to get the job done. is that what you prefer? more so than a genie? i have heard that the new genies are the gnats behind, even better than a jlg.

so back to my machine... it has been working perfectly for the past 2 days now, stupid electronic things. at least i got my current job done and can maybe put a pressure gage on. do you have any idea where the quick connect fitting is you speak of?

thanks

 

[willie59]

atco, so you obviously are a mechanic, what do you primarily work on? i read on some other post that you would just go get a jlg to get the job done. is that what you prefer? more so than a genie? i have heard that the new genies are the gnats behind, even better than a jlg.

so back to my machine... it has been working perfectly for the past 2 days now, stupid electronic things. at least i got my current job done and can maybe put a pressure gage on. do you have any idea where the quick connect fitting is you speak of?

thanks

Man where you been???

A mechanic? Well...that is the profession I have chosen to follow for the last 25 years, with a little stint of operating (and mechanic) drill rigs for 7 years in the middle. I am JLG and Versalift certified. I am partial to JLG for two reasons. 1) they do build a very good machine, and they make an attempt to keep a machine simple in it's components and operation. 2) being from the eastern U.S., shipping from JLG is much quicker for me. If I order something from Genie (in Washington state), it is 7 days ground shipping. So if I need a part...it has to come rapid freight...more cost. I have no problem with Genie whatsoever. And I'll give them this; compared to JLG, they do a better job with their schematics, much more easy to read and work with.

As for the quick connections, you just have to look for them. JLG has always done a pretty good job of installing quick connections for pressure gauges to test the main hyd pressure lines. As opposed to many machines that you have to "tee into a line" to check pressure. You should find these connections with rubber caps on them. There should be one somewhere for testing main pump output. I can't remember exactly what the "quick connect" coupler you need is, I've had one for so long I don't remember what style coupler it's called.

Another thing you might want to look at is the hyd filter in the tank. JLG usually has a gauge that shows the pressure of the return oil going into the filter. High pressure shown on the gauge indicates the filter is getting clogged and will open the by-pass valve and oil will by-pass filter. That's one thing you don't want to happen. JLG machines have a lot of orifice's in their hyd circuits and they are very sensitive to debris floating around in the hyd system.

As for your problem, it's hard to say yet what the problem is, as it comes and goes. Until we get something more consitent; as the old saying goes...if it ain't broke, I can't fix it!

 

[John C.]

Just a thought here but it was mentioned that the harness between the basket and the control valves had a patch job put in. I've worked on Grove, Skyjacks and even a Skywitch and seen where in some cases two wires have to be energized to operate one function.

I've had issues with those long harness and found that when the basket is extended the movement on the wires causes some grief at times. The only way I found the fix the problem for good was to replace the harness.

Good Luck!

 

[eianewb]

john, i had thought about that, but i am sure it isn't cheap. any idea what it costs?

maybe you'd know atco.

thanks

 

[willie59]

Just a thought here but it was mentioned that the harness between the basket and the control valves had a patch job put in. I've worked on Grove, Skyjacks and even a Skywitch and seen where in some cases two wires have to be energized to operate one function.

I've had issues with those long harness and found that when the basket is extended the movement on the wires causes some grief at times. The only way I found the fix the problem for good was to replace the harness.

Good Luck!

Your absolutely right John C. That's usually where these kind issues take you; the control cable going from ground controls to platform. I just haven't got there on this one yet, but I'm considering it. It can be caused by some kind of damage to control cable (usually at tip of boom where platform mounts) and the very common occurance of cable failure at the power track, that's that big chain link looking thing that's rolls out cable and hose assemblies when telescoping. Over a period of time, the constant bending and relaxing of the wires inside the cable bundle cause wires to either break or two wires to rub together until the insulation of the wires are compromised and cross over to each other. And no, it's not really cheap, heah...any form of copper ain't cheap nowdays. And some folks try to get by using improper replacement cable, such as a typical "SO" or "SJ" rubber cable. It won't work because these cables aren't designed for constant flexing. You have to use some form of robotic or pendant cable, something made for constant flexing. But do give a JLG dealer a call. The last few cable jobs I have done, JLG's price is right there with local wire/cable suppliers. I think this is because JLG buys miles of this cable in a years time for manufacturing their machines, so they probably give a good price for it. As for cost? Not for sure. I recently did an 80HX+6, that's roughly 120 feet of cable, and I did all three cables. It used a 16/32, a 12/4, and a 12/3. So your talking three cables 120' long, the cost was around $1,800. But since yours is a 40' lift, you probably won't need more than maybe 60'. And you may get by with replacing the control cable and not the 12/4 power supply cable. A wild guess...you may be looking at 300 - 500 bucks. Have you got a JLG dealer in your area that you work with?

 

[eianewb]

300-500 isn't horrible. i was trying to troubleshoot something last year, and i think they got tired of talking to me, lol. they printed me off the entire owners manual and parts manual for it. lol. anyways, i think that the schematics from jlg sure have something to be desired.

i ended up replacing a pilot valve that, as it turns out, was ok but we had it narrowed down to that or the controller and the controller didnt fix it. and then the valve didnt fix it. so i finally figure that the controller is ok and the valve was ok, and i check the continuity of the wire a it was broken somewhere. so yeah... i fixed it with an extension cord to get by. i figured that someday ill fix it right. and if it is only 300-500 i might get one ordered for when something else goes wrong.

i have since found that where the basket attaches there have been several wires spliced there. i am sure that someone hooked them on something and didn't know it and then moved the machine. it is kind of a stupid design having them all exposed the way they do right there.

 

[willie59]

Yeah, the cables are kinda exposed there...but that's the way it is on pretty much all brands. The cables and hoses there have to have enough slack in them to allow for basket rotating and tilt. One thing you could try is just assume you have a problem with the wire that's going to the dump valve circuit. If your machine has the original JLG cable and everything is proper, that should be the red/orange wire of the 16/30 cable connected to terminal #23 of the platform terminal strip. Just figure that wire is bad. You should have extra cables that you can switch out and use at terminal 23 instead of the red/orange. I'm seeing a couple of "spare" wires on the diagram; red - terminal #2, orn/blk - #9, and orn/red - #14. You could just switch over to one of these spares by connecting them to the proper terminals in the upper and lower control boxes and see if your problem goes away.

 

[od1]

Hi All
This is a question about a JLG 40F Manlift. I'm looking for a wiring diagram. Sorry for posting it here. You can email me at od@intersat.cc

Thanks

 

[willie59]

Welcome to the forum od1. :usa

Make 3 posts to the forum, then you can start your own thread about your question and we'll see if we can help you out. I don't know if I can even find my 40F diagram, I haven't worked on one in years, but we'll see if we can figure out something.

 

[od1]

Thanks for your time on this project. The 40F is in pretty good shape for its age. The wiring has been spliced 5 times and needs to be redone. Some of the wire is aluminum 20 awg spliced into copper 16 awg. Two of the controllers were wired with bell tel. wire. Unreal. The hoses look original as well. JLG in PA don't return calls. I contacted Gates to find out what hoses to use. Someone told me to stay away from Gates. They suggested Parker or Aeroquip. I'm not sure of the lenths needed or what type of connectors to use. I got a great deal on some ultra flex T1 cable. Good ruged cover rated 600 volt 25 numbered cables with fine copper wire 16 awg. I don't know which valves are on this so I bought 80 feet to be safe.
Any input you have will be put to good use. You seem to have a lot of knowledge. Thanks in advance for your time and effort.
Regards
OD1

 

[od1]

I just had another thought about saftey. Is there a safty valve on the 40F ? Like if a hose failed will the lift lock or would it just collapise. If it has nothing could something be fitted ?