The JLG 40F Boom Lift Dilemma

[ATCOEQUIP]

Originally Posted by od1

Hey Atcoequip
Is there any special technique for removing and servicing the brakes?
How do the brakes engage? Any ideas?

Wow dude, it's been so many years since I've worked on a 40F, let's just say...I've slept since then.

I don't recall the brakes being difficult to service. Take the cover off of the drive wheels and you'll see the drive motor and brake assembly. The brakes are spring applied. When the machine is at rest with the engine not running, the springs apply pressure to the brake disks to hold the machine. Even with engine running, the brakes are applied until you select Drive. I can't remember on a 40F, but later JLG machines used a solenoid valve to apply hyd pressure to overcome springs and release brakes when drive was selected. Can't remember for sure, but I would say the 40F used a similar method. Can you remove the drive axle cover and post a pic of the drive motor and brake?

[od1]

Originally Posted by ATCOEQUIP

Wow dude, it's been so many years since I've worked on a 40F, let's just say...I've slept since then.

I don't recall the brakes being difficult to service. Take the cover off of the drive wheels and you'll see the drive motor and brake assembly. The brakes are spring applied. When the machine is at rest with the engine not running, the springs apply pressure to the brake disks to hold the machine. Even with engine running, the brakes are applied until you select Drive. I can't remember on a 40F, but later JLG machines used a solenoid valve to apply hyd pressure to overcome springs and release brakes when drive was selected. Can't remember for sure, but I would say the 40F used a similar method. Can you remove the drive axle cover and post a pic of the drive motor and brake?

Well it's 1:40 . I guess it's not going to get any warmer out there today. I'll get that plate off in a few minutes and get a pic. or two.
Did you ever work on a JLG 40C circa 1973? It looks a lot like the 40F.
If so let me know what you think about them. There's 1 for sale.

[ATCOEQUIP]

Nope, haven't worked on a C. Only as far back as 40F.

[Xcopterdoc]

If I remember right , the 40F used the same ole Mico brake assy, spring applied, hyd released, when the threshold on the controller was engaged. I still have JLG nightmares! They mostly subsided tho when I started working on Genies. Of course they were enough old H's and TB's around to keep ya jumpin'! LOL! Hey ATCO.. ever work on the old UNO lifts? The old POS with the cable operated brake pedal in the basket? Very nice! And of course all bang bang controls with RexRoth valves!

[ATCOEQUIP]

Yep, I've worked on an UNO, many moons ago, I had forgot about that...until now.

Worked on too many Economy and Snorkel. Got a PRO126 Snorkel that's about to drive me crazy right now! Stupid thing!

I never minded working on Genie machines. One thing Genie does really well is their wiring systems and schematics. JLG does good wiring, but their schematics could be better. I'll be Ok with Genie...unless they take on the Terex mentality. Not too fond of Terex boom lifts. Terex aquired the old Mark Lifts, and proceeded to make them not much better. Just more complicated.

[od1]

Originally Posted by ATCOEQUIP

Wow dude, it's been so many years since I've worked on a 40F, let's just say...I've slept since then.

I don't recall the brakes being difficult to service. Take the cover off of the drive wheels and you'll see the drive motor and brake assembly. The brakes are spring applied. When the machine is at rest with the engine not running, the springs apply pressure to the brake disks to hold the machine. Even with engine running, the brakes are applied until you select Drive. I can't remember on a 40F, but later JLG machines used a solenoid valve to apply hyd pressure to overcome springs and release brakes when drive was selected. Can't remember for sure, but I would say the 40F used a similar method. Can you remove the drive axle cover and post a pic of the drive motor and brake?

[OFF]

Nice stuff OD1

I can't get over how original that machine is, everything is still wearing the factory yellow paint.

[ATCOEQUIP]

Geez, it's been years since I've seen those things!

If I remember correctly, there should be a gap between that steel block (has the jamb nut against it) and the end of the cylinder body. I'm thinking when the block begins to contact the end of the cylinder, the brake pads are getting worn. I believe the cylinder rod is threaded into the block and the jam nut prevents cylinder rod from turning. You have to loosen/remove the jam nut, then turn the cylinder rod to release brake pressure. Then you can remove components to service brakes. At least, I think that's the way they worked.

[ATCOEQUIP]

Originally Posted by Xcopterdoc

Hey ATCO.. ever work on the old UNO lifts? The old POS with the cable operated brake pedal in the basket? Very nice! And of course all bang bang controls with RexRoth valves!

LoL...ever worked on a Zefer Lift? They billed their scissor lifts as "Environmentally Friendly" because they used no hyd oil. Had no hyd cylinder to raise platform. They used an electric motor driving a 90 degree gearbox which turned a long screw. The screw went into a screw block mounted to the scissor arms. Turning the screw CW and CCW made the scissor go up and down. Enviro Friendly, eh? They were electric, they still used 4 lead acid batteries!

[od1]

Originally Posted by OFF

Nice stuff OD1

I can't get over how original that machine is, everything is still wearing the factory yellow paint.

Every time I remove some plating I find more original hoses or cable.

[ATCOEQUIP]

Originally Posted by od1

Every time I remove some plating I find more original hoses or cable.

Except the wiring at the platform controls.

[od1]

Originally Posted by ATCOEQUIP

Geez, it's been years since I've seen those things!

If I remember correctly, there should be a gap between that steel block (has the jamb nut against it) and the end of the cylinder body. I'm thinking when the block begins to contact the end of the cylinder, the brake pads are getting worn. I believe the cylinder rod is threaded into the block and the jam nut prevents cylinder rod from turning. You have to loosen/remove the jam nut, then turn the cylinder rod to release brake pressure. Then you can remove components to service brakes. At least, I think that's the way they worked.

I think I see what you mean. I can see about a 16th maybe a little more than that left as far as the pads go. There seems to be a grove cut in the middle which would be even at around a 32 nd. I’m guessing that’s its minimal tolerance. The brake seems tight at least on that side, but it doesn’t seem to have enough pressure. There is some grime there but it should be dry enough to make contact. If I try and adjust it and it doesn’t release all of the way will it over heat anything?

I guess towing it short distances would be out of the question wouldn’t it. If the brakes are on as the default they would heat up for sure. The other issue with towing that I wanted to ask is would I damage the drive motors by towing it say a mile or so?

[ATCOEQUIP]

As off mentioned previously, disconnecting drive wheels from motors/brakes is easy. On the outside of the Torque Hubs is a plate with a bump on it, right on the center of the Torque Hub. It's held on by (2) 1/4" bolts. Remove the two bolts holding the plate, the plate comes free, then flip the plate over so the bump points inward. Re-install plate with the removed bolts. The bump now pushes a shaft in that disconnects the planetary hubs from the drive motors and brakes. The machine will free wheel now, but go slowly because your still turning the planetary gears inside the torque hubs.

[od1]

Originally Posted by ATCOEQUIP

As off mentioned previously, disconnecting drive wheels from motors/brakes is easy. On the outside of the Torque Hubs is a plate with a bump on it, right on the center of the Torque Hub. It's held on by (2) 1/4" bolts. Remove the two bolts holding the plate, the plate comes free, then flip the plate over so the bump points inward. Re-install plate with the removed bolts. The bump now pushes a shaft in that disconnects the planetary hubs from the drive motors and brakes. The machine will free wheel now, but go slowly because your still turning the planetary gears inside the torque hubs.

Man that’s amazing. That’s great to know.
I’ll have to reread everything again. I don’t remember talking about that before.
How fast do you think I can roll with it? Is there a hitch plan anywhere for it?
There seems to be a setup for it on the front side (non drive side).

Thanks again for all of your input ATCO. It’s a huge help.

[od1]

Originally Posted by ATCOEQUIP

Except the wiring at the platform controls.

Man that’s the truth!