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The JLG 40F Boom Lift Dilemma

TheBigDog

Member
Joined
Jun 2, 2021
Messages
11
Location
Ohio
@OFF, I forgot to thank you for the info....it is working again!

Also, is there a place to look up the serial number to verify the year it was made?

Is the starter relay black or silver? Does it have 2 small terminals, or only 1?

black with 3 terminals (only one small terminal) NAPA UNI-ST82
black with 4 terminals (two small terminals) NAPA UNI-ST81

Silver with 4 terminals NAPA UNI-ST85
 

OFF

Senior Member
Joined
Sep 30, 2009
Messages
1,044
Location
Alberta, Canada
Occupation
HD Mechanic
You're very welcome, I'm always glad to help.

The only way I know of to date an old JLG serial number is to contact JLG or have a friendly JLG dealer contact them for you.

All my old contacts are dead by now I'm sure, and we went Genie in about 1990, so I haven't made any new JLG contacts. :)
 

Jwells

New Member
Joined
Sep 27, 2021
Messages
2
Location
Ogdensburg, N.Y.
I am new to this and not really much of a computer guy, but I bought a 40’ jlg lift a year or so ago. It’s a 1980 and now none of the functions are working at all. The local dealer only could tell me about this forum and couldn’t find what he needed for a wiring schematic. A lot of the wires and fuses are burnt up in the box behind the hr meter. Do I have scrap metal now or is there anything out there?
 

OFF

Senior Member
Joined
Sep 30, 2009
Messages
1,044
Location
Alberta, Canada
Occupation
HD Mechanic
Hello JWells. I can email you JLG 40F manuals and wiring diagrams as well as try and answer any questions you may have.

I just need an email address to send the manuals to.

Best way to do that is to click on my name, and in the little box that comes up, choose "start a conversation". That will send me a private message where you can put your email address without the whole world seeing it.
 

OFF

Senior Member
Joined
Sep 30, 2009
Messages
1,044
Location
Alberta, Canada
Occupation
HD Mechanic
@OFF

Also, is there a place to look up the serial number to verify the year it was made?

On units made before 1980, the first two digits on the serial number seems to me to be the year. People have told me that's wrong, but I don't think so. I worked on a lot of JLG's made in the 70's and the age seemed to fit.
 

Jwells

New Member
Joined
Sep 27, 2021
Messages
2
Location
Ogdensburg, N.Y.
Ok thank you! Also is it possible to buy original parts for a machine this old, such as that hr meter box I mentioned? Or do I look for an old dinosaur burial ground to try and get those parts? The local dealer can’t seem to have any luck, and the bigger dealers towards the bigger cities don’t want to help because it’s over 20 yrs old.
 

Missingsoldier

New Member
Joined
Sep 2, 2020
Messages
4
Location
Arkansas
I have a new problem with my 40f. My basket level cylinder was leaking so I rebuilt it and now it will not go in and out. I am getting fluid to it but it will only go out and not back in. Is there a specific way to install it to get the air out?
 

OFF

Senior Member
Joined
Sep 30, 2009
Messages
1,044
Location
Alberta, Canada
Occupation
HD Mechanic
Ok thank you! Also is it possible to buy original parts for a machine this old, such as that hr meter box I mentioned? Or do I look for an old dinosaur burial ground to try and get those parts? The local dealer can’t seem to have any luck, and the bigger dealers towards the bigger cities don’t want to help because it’s over 20 yrs old.

Start by looking up the JLG part number of what you need in the parts manual. Google that part number, you might get lucky. Many places sell obsolete parts and "jobber" parts.
Also give that part number to your JLG dealer so he can run it. Dealers can't look up a part that old, but they can still run the number in the JLG system. Those two methods are all you have to work with.

That main control box is going to be a tough find. However, I did have a NOS 40F basket control box in my dead stock, (I gave it to the person who started this thread) so it's not impossible.
Good luck
 

OFF

Senior Member
Joined
Sep 30, 2009
Messages
1,044
Location
Alberta, Canada
Occupation
HD Mechanic
I have a new problem with my 40f. My basket level cylinder was leaking so I rebuilt it and now it will not go in and out. I am getting fluid to it but it will only go out and not back in. Is there a specific way to install it to get the air out?

Have a look in the service manual for a bleeding procedure for the basket leveling cylinder.
Make sure your lock valve is installed correctly and your hoses are on right. Have you tried tilting the basket from the ground controls? If you get it to move, run it fully extended to fully retracted a couple times and all air should be gone.
 

maple2

Member
Joined
Sep 10, 2014
Messages
15
Location
vermont
Just popped hydraulic hose tonight on the basket up and down. Any tricks in changing this line? Anything to watch out for? Looks like a long hose!
 

OFF

Senior Member
Joined
Sep 30, 2009
Messages
1,044
Location
Alberta, Canada
Occupation
HD Mechanic
It is a long hose alright. What was the reason for the failure? Wear spot? How are the other hoses in the boom looking?

not a nice job for sure. The method is to couple a new hose to one end of the old hose, and pull the new hose in while pulling the old hose out. Problem is that those hoses are often tangled and wrapped up around each other, and not as easy as it sounds.
Somewhere in the archives I have hose lengths, I'll see what I can find.
 

OFF

Senior Member
Joined
Sep 30, 2009
Messages
1,044
Location
Alberta, Canada
Occupation
HD Mechanic
According to the JLG factory 40F build sheets.......you need 550 inches of 1/4" hydraulic hose (#4 hose) for the basket tilt function. The fittings are male 1/4" NPT.
 

TheBigDog

Member
Joined
Jun 2, 2021
Messages
11
Location
Ohio
It is a long hose alright. What was the reason for the failure? Wear spot? How are the other hoses in the boom looking?

not a nice job for sure. The method is to couple a new hose to one end of the old hose, and pull the new hose in while pulling the old hose out. Problem is that those hoses are often tangled and wrapped up around each other, and not as easy as it sounds.
Somewhere in the archives I have hose lengths, I'll see what I can find.
@OFF , if you find the info on all the hose lengths, I could probably use them as I have several that are showing a lot of wear or are starting to crack.
 

TheBigDog

Member
Joined
Jun 2, 2021
Messages
11
Location
Ohio
So when driving the lift, the machine comes to an abrupt stop as soon as you return the joystick to center. Is this normal on this machine or should it be a more gentle deceleration? If it should be more gentle, what would I start looking for as the probable issue?
 

OFF

Senior Member
Joined
Sep 30, 2009
Messages
1,044
Location
Alberta, Canada
Occupation
HD Mechanic
So when driving the lift, the machine comes to an abrupt stop as soon as you return the joystick to center. Is this normal on this machine or should it be a more gentle deceleration? If it should be more gentle, what would I start looking for as the probable issue?

On the "F" series JLG's there is no "ramp" feature to the controllers. If you're driving and you take your foot of the foot switch or let go of the controller, the brakes are on and the wheels are locked up at that moment. Sudden, abrupt, a little rude.

The feathering or the ramp feature on controllers did start being used until the "H" series.
 

OFF

Senior Member
Joined
Sep 30, 2009
Messages
1,044
Location
Alberta, Canada
Occupation
HD Mechanic
@OFF , if you find the info on all the hose lengths, I could probably use them as I have several that are showing a lot of wear or are starting to crack.

You want lengths for all 4 boom hoses? It won't be today, but I'll get them listed in here. There are only 4 hoses in the boom, right? Basket tilt and basket swivel?
 

TheBigDog

Member
Joined
Jun 2, 2021
Messages
11
Location
Ohio
You want lengths for all 4 boom hoses? It won't be today, but I'll get them listed in here. There are only 4 hoses in the boom, right? Basket tilt and basket swivel?

Yes, there are 4 hoses. I know that two are for basket tilt and figured the other two were for the telescope function.
 
Last edited:

TheBigDog

Member
Joined
Jun 2, 2021
Messages
11
Location
Ohio
On the "F" series JLG's there is no "ramp" feature to the controllers. If you're driving and you take your foot of the foot switch or let go of the controller, the brakes are on and the wheels are locked up at that moment. Sudden, abrupt, a little rude.

The feathering or the ramp feature on controllers did start being used until the "H" series.

Ok, I had someone check it out and they thought maybe there was an accumulator or something that might be bad and causing the brakes to suddenly lock vs a ramp down / smooth deceleration.
 
Joined
Apr 14, 2021
Messages
4
Location
Georgetown CA
I am wanting to fix the leaking drive motors. Does any one have a part number for the seals? Went to one hydraulic shop and they couldn't/wouldn't help me. Trying another shop but if anyone has those numbers that would be a huge help. Thanks
 
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