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The JLG 40F Boom Lift Dilemma

A2jake

New Member
Joined
Jun 30, 2020
Messages
2
Location
Missouri
I have owned it for 25 years or more, used to by parts from ASAP in Pa. but that’s no longer an option.
I would just call and they would send what ever I needed so I never needed a parts book.
Never used the machine for hire, just around our personal property and could absolutely Not live without it, so convenient and safe to get where you need to go, (up high).
 

OFF

Senior Member
Joined
Sep 30, 2009
Messages
1,047
Location
Alberta, Canada
Occupation
HD Mechanic
I've been told that the first two digits of a JLG serial number are not the year of manufacture. There is really no way to tell, other than to contact a friendly JLG dealer and get him to run your serial number. Even the older machines seem to remain in their system.
 

thelandscaper9726

New Member
Joined
Oct 27, 2020
Messages
3
Location
mass
Popping in to say how glad I am to see this forum is still alive... I'm the proud owner of a brand New-to-me JLG 40f from 1979..... Has the Bertea valves on it, needs new hoses going up to basket tilt and needs a complete overhaul on the wiring:rolleyes:. Hopefully I can get it it brought back to life again, as things are definitely not running quite right. I've only made it through 11 pages of the 80 so far, so I'm not going to ask any questions until I finish reading through everything, so much information to digest! One thing for sure I'll need is the wiring schematics, and it seems like OFF is the one that holds these magical documents in their possession. I hope it wouldn't be too much trouble to ask for those
 

Missingsoldier

New Member
Joined
Sep 2, 2020
Messages
4
Location
Arkansas
I have a new to me 1977 40f and it keeps blowing the seal on the turntable gear. I know it’s blowing fluid out of the drive motor but cannot locate the problem. There are two hoses that come from the pump, two that go to the tank, and two that go to a pipe looking thing up top. I don’t know where to start. I do not know what the purpose is for the pipe looking thing but it doesn’t seem to have fluid in it. If it’s supposed to then I may have a restriction in the lines. If not is there a pressure relief valve somewhere that I need to replace? Any help would be greatly appreciated. If I can’t figure it out soon I think I can take out the fill plug on the gear drive and put in a nipple. From there I can run a hose to the top of the tank and let it recirculate the fluid. It runs and operates fine it is just making a mess
 

thelandscaper9726

New Member
Joined
Oct 27, 2020
Messages
3
Location
mass
I have a new to me 1977 40f and it keeps blowing the seal on the turntable gear. I know it’s blowing fluid out of the drive motor but cannot locate the problem. There are two hoses that come from the pump, two that go to the tank, and two that go to a pipe looking thing up top. I don’t know where to start. I do not know what the purpose is for the pipe looking thing but it doesn’t seem to have fluid in it. If it’s supposed to then I may have a restriction in the lines. If not is there a pressure relief valve somewhere that I need to replace? Any help would be greatly appreciated. If I can’t figure it out soon I think I can take out the fill plug on the gear drive and put in a nipple. From there I can run a hose to the top of the tank and let it recirculate the fluid. It runs and operates fine it is just making a mess
Do you have any pictures? I'm not experienced with this problem on this machine, but I have seen instances where hydraulic components blow their internal seals and start making a mess through a weep hole. Usually the weep hole is there to prevent pressure build up from causing further damage
 

Missingsoldier

New Member
Joined
Sep 2, 2020
Messages
4
Location
Arkansas
Do you have any pictures? I'm not experienced with this problem on this machine, but I have seen instances where hydraulic components blow their internal seals and start making a mess through a weep hole. Usually the weep hole is there to prevent pressure build up from causing further damage


I don’t have any pictures at the moment but the hydraulic motor that sits on top of the turn table gear is blowing fluid past the shaft seal. It is bolted to the top of the turn gear so it fills it with hydraulic fluid until it pushes the lower seal out. I replaced the shaft seal on the motor but it still blows fluid out. The seal is only rated for low pressure so it is definitely Over pressuring the seal.
 

thelandscaper9726

New Member
Joined
Oct 27, 2020
Messages
3
Location
mass
From what I've learned from reading through this entire thread, I believe that the rotate motor is the same as the drive motors, and that some of them came without drain back to tank line. This would cause them to blow a seal after they started to wear down a bit. One solution was to add a drain back to tank on it, but some people have found that on their drive motors there isn't a threaded hole to add a line to relieve the pressure so it would take some strategic know-how to figure out where/if you could add one.... Somebody more knowledgeable than I will have to chime in though, I am a novice when it comes to this.
 

7fixer

New Member
Joined
Nov 6, 2020
Messages
3
Location
Council, ID
Hey all. Just joined.
Ive read through the first 12 pages so far and have learned a bit. Still getting a grasp on the valve function and which are which.
Im helping work on, what I'm pretty sure is a 40G. The owner says that he thinks it was pieced from two machines. Ive borrowed it for some work on my roof and it has symptoms that show up after several hours of use. it does pretty good until certain functions stop working from the basket. Specifically lower and rotate L&R. Raise still works. Which is an issue when you can raise, but not lower, LOL .
Two things in common when the problems arise. We been running for 4-5 hrs and Ive used the 110v power to run a skil saw for 15-45 min. I was in the basket when these happen. My helper is able to use the toggle switches on the ground to lower.

1105201154.jpg 1105201153_HDR.jpg 1105201154a.jpg
 

7fixer

New Member
Joined
Nov 6, 2020
Messages
3
Location
Council, ID
Also, we had an extra pedestal so took two PQ joysticks and tried swapping those, they seemed to make no difference.
These symptoms happened twice. About a day after the first time, things were acting normal again. The right rotate has been slower from the beginning and reverse drive has less power than forward
 

Edypaul

Member
Joined
Mar 3, 2018
Messages
24
Location
Florida
Occupation
A&P Mech. Massy 135 ,Case 480-LL , JLG Lift
Good morning All. Need help finding a manual for my JLG 40-45. Not having much luck. I have seen a few posts ,in this thread about 40-45s so hoping to find a Manual Id be willing to pay for one. I would like to rebuild this Machine! 20201108_125650.jpg 20201108_125427.jpg 20201108_125438.jpg

Thx Ed
 

dn29626

Well-Known Member
Joined
Jan 1, 2017
Messages
55
Location
SC
Push button switch at the engine needs replacement. Oh well.
But, the reasons for todays post...The rotating on/off switch at the basket.
I opened the control box to tighten the switch so it will not move while trying to use it and noticed wires hanging loose.
Am i correct...there are 5 places to connect wires, but the switch uses only 3 of them?
 
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OFF

Senior Member
Joined
Sep 30, 2009
Messages
1,047
Location
Alberta, Canada
Occupation
HD Mechanic
Hey all. Just joined.
Ive read through the first 12 pages so far and have learned a bit. Still getting a grasp on the valve function and which are which.
Im helping work on, what I'm pretty sure is a 40G. The owner says that he thinks it was pieced from two machines. Ive borrowed it for some work on my roof and it has symptoms that show up after several hours of use. it does pretty good until certain functions stop working from the basket. Specifically lower and rotate L&R. Raise still works. Which is an issue when you can raise, but not lower, LOL .
Two things in common when the problems arise. We been running for 4-5 hrs and Ive used the 110v power to run a skil saw for 15-45 min. I was in the basket when these happen. My helper is able to use the toggle switches on the ground to lower.

Always with these machines, first thing you check is the available battery voltage in the basket control panel. When/if it drops below 11 volts, all sorts of bad things start to happen. Everything shuts down at about 9 volts. Any yellow wire should have power with your foot on the pedal.
 

OFF

Senior Member
Joined
Sep 30, 2009
Messages
1,047
Location
Alberta, Canada
Occupation
HD Mechanic
Popping in to say how glad I am to see this forum is still alive... I'm the proud owner of a brand New-to-me JLG 40f from 1979..... Has the Bertea valves on it, needs new hoses going up to basket tilt and needs a complete overhaul on the wiring:rolleyes:. Hopefully I can get it it brought back to life again, as things are definitely not running quite right. I've only made it through 11 pages of the 80 so far, so I'm not going to ask any questions until I finish reading through everything, so much information to digest! One thing for sure I'll need is the wiring schematics, and it seems like OFF is the one that holds these magical documents in their possession. I hope it wouldn't be too much trouble to ask for those

40F manuals are yours for the asking. All I need is an email address to send them to. I've sent out probably a hundred of them already. JLG's lawyers haven't contacted me yet, so I'll continue to send them out!
 

dn29626

Well-Known Member
Joined
Jan 1, 2017
Messages
55
Location
SC
I replaced a switch. Engine is spinning over using the ground controls, but not starting.
I want to check parts in the distributor.
The rotor button is stuck. Any suggestions of removing it without damaging it?
I expect all the parts inside the distributor need a good cleaning/sanding.
 
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