The JLG 40F Boom Lift Dilemma

[dbris]

Good idea since I wanted to thank you publicly. This is a great group and I'm sure I'll have some more questions.

 

[willie59]

Good idea since I wanted to thank you publicly. This is a great group and I'm sure I'll have some more questions.

There ya go, got your 3 posts in. Won't be long you'll be a Junior Member and you can post a pic of your 40F.

 

[Tim_]

Bingo! Problem sloved. A friend took the schematics OFF provided and had them blown up to 11 x22 and everything was clear. Found the dump valves on the cross brace above the pump and used the schematics to find the dump solenoid and it was not pulling in. I jumped across it just to see if that was the problem and everything came to life. Thanks for all the help. I plan on taking some pictures of the items I found and I'll post them soon. Thanks again Tim_

 

[willie59]

Good to hear you got it figured out Tim. Post some pics soon.

 

[dbris]

Thanks guys, the electrical drawings helped a lot. I still have an issue with the dump valve for the proportional side (lift, swing and drive) since it seems to be different from the drawings. I've attached (I hope!) pics of both valve stacks in hopes that someone can help me. There is no dump solenoid on the lift-swing-drive stack but there's a valve with 2 coils on it above the junction box (you can only see 1 coil in the pic - the other one is on the back) and I am assuming that is the dump and hi drive valve but without the hydraulic schematic I'm just guessing. The other valve stack does have a solenoid dump valve on top.
Am I even close here? Also, can someone tell me where to find the ID plate on the 40F? I can't find a serial # anywhere.
Even with all the problems, this thing is kind of fun to play with - I learn something new every time work on it!

 

[willie59]

Wow, I haven't looked inside one of those units for many moons.

Yep, you have Racine proportional valves for sure. Haven't worked on any of those myself, just the Bertea valves. OFF would know more about that machine. But the electrical schematic shows a proportional dump valve. I can see the bang valve with the dump valve in the inlet section in pic 2. Not sure what I'm looking at in pic 1, not enough view there for me to tell. You will have a high drive solenoid valve in there somewhere. The hi drive is very simple; you have a multi section hyd pump. One pump feeds oil to the proportional valve section. This gives you drive. Another pump section goes to the high speed valve, which is actually another dump valve, it dumps the oil from it's pump section back to tank, unless, you select hi drive, then it diverts the oil that was being sent to tank to combine with oil being delivered from other pump, going to proportional valves. Now you have two pumps providing increased oil flow to proportional valves, giving you hi speed drive. But you should have a dump valve for the proportional valves as well. You should be able to follow your hoses from the pumps and determine where the dump and high speed valve is.

 

[dbris]

Thanks ATCO, that makes sense on the hi drive. Sorry about the picture, it's one that I just happened to have but I'll get out there in the next few days and get some better ones. There is a manifold of sorts on the left side of the proportionals but no solenoid. It has 5 ports on it, 2 go to a filter (loop) 1 is a return to the tank, 1 is direct pressure from the pump and one goes through a check valve to the solenoid valve that's above the Hobbs meter in the picture. That valve in turn has 1 port to the third pressure output of the pump and a return to the tank,and it also has 2 coils. I'm sure that that's the hi drive from your description of how it works, but why 2 coils and where's the dump valve?
I'm sure some better pics will help. It's neat to learn something new every time I look at this forum!

 

[Tim_]

Dbris, I believe your on the right track. It looks alittle different than mine but for the most part it's the same. The Hi drive valve is the one in the picture above the Hobbs meter and junction box. If you find your pump and follow the middle line it goes to the dump valve for the bang-bang (steer, telescope, and level),mine was located in the middle high on a cross brace with the dump valve for the proportional stack, side by side. If anyone has a hydraulic schematic I'd love to have a copy. And as OFF stated before not all of these machines are the same. Hope this helps and like you I learn something new everytime I work on it. Tim_

 

[EMT]

funny thing this dinasour, I ran in to the same problem.
I had the same electric schematic. witch did help but not totally.
I had no drive,swing, lift, which is controlled by the same dump valve.
I found 2 problems 1st there was contaminants in the hydraulic systems which was sticking the dump vale open running hyd psi back to tank. I removed and cleaned dump valve. changed hyd filter. then 2nd problem, electric harness is old and has too much resistance in the harness to the controll valves. I cleaned grounds, charged the battery and watched the unit work.
Just a couple of possibilities. Bye the way the dump valve on your left is the one that controls the lift,drive,swing. hope that helps you!

 

[dbris]

Ok, here are some better pictures of the proportional valves and the hydraulic schematic that I reverse engineered. The schematic may not be 100% accurate but it should be pretty close. If anyone has any corrections, please send them to me. I hope it's readable but if not, I have it in a PDF that I'd be happy to send - just ask. The proportional valves do not seem to have a dump valve of any kind. The pressure comes direct from the pump to the manifold thing on the left end of the valve stack and all functions work without either coil on the hi drive solenoid connected. Even though everything works ok, I'd sure like to know how it's supposed to work, and of course, why there are 2 coils on the hi drive!

 

[dbris]

No pictures? Well, lets try it again.

 

[OFF]

In my experience the proportional valve bank (lift/swing/drive) always has a dump valve. Looking at your second picture, in the second set of pictures, the big lump to the left of the three proportional valve sections looks to me like it may contain the dump valve for that section.
Follow the hydraulic hose coming from the largest section of the pump (closest to the engine flywheel) and it should lead you directly to the dump valve you seek. There were "Integral dumps" (dump is part of the valve body).
The manual shows 2 different hyd. schematics - one with 3 remote dump valves and the other with only one for high drive.

I can see I need to put top priority on getting this manual copied and sent out to you guys.

 

[willie59]

I can see I need to put top priority on getting this manual copied and sent out to you guys.

Hey OFF, I wonder if you were to take it to a print shop, would they say "this is copyright material". Then you could say, "well, the copyright must be expired...because this material is no longer available from the people who produced it and obtained the copyright in the first place!" LoL

 

[dbris]

Thanks Off, I think you're right that the lump on the end contains the dump valve but I believe that it works differently than the other valves. The dump valve seems to be integral to the valve stack and when any of the proportional valves are activated by their solenoid, the dump valve does it's thing. It does not have it's own solenoid, it's actuated internally. I'd be happy to help out with $$ if we could get access to that manual!

 

[OFF]

Hey OFF, I wonder if you were to take it to a print shop, would they say "this is copyright material". Then you could say, "well, the copyright must be expired...because this material is no longer available from the people who produced it and obtained the copyright in the first place!" LoL

That's what I'm worried about. I don't want JLG's lawyers to come knocking on my door one day.

 

[willie59]

That's what I'm worried about. I don't want JLG's lawyers to come knocking on my door one day.

LoL, that's what I'm wondering. Can they come after you for something they don't even have available nowdays? Curious eh?

 

[OFF]

Thanks Off, I think you're right that the lump on the end contains the dump valve but I believe that it works differently than the other valves. The dump valve seems to be integral to the valve stack and when any of the proportional valves are activated by their solenoid, the dump valve does it's thing. It does not have it's own solenoid, it's actuated internally. I'd be happy to help out with $$ if we could get access to that manual!

Here's the same lump


And here's what the back of the lump looks like.



I'm 99.99% sure it would have had a solenoid hooked to it just like your other dump valves. Any big hunks of tape hanging around that look like a solenoid by-passed?

 

[OFF]

LoL, that's what I'm wondering. Can they come after you for something they don't even have available nowdays? Curious eh?

I gotta do it. I wonder if I split the manual into 3 files (Operators/Service/Parts) if they'd be too large to email? PDF's are small, right?

If the copier/scanner/printer/fax at the office was my friend, I'd have copies
printed by now. I can't get it to double side properly. I may have to ask for help

 

[dbris]

Here's the same lump
View attachment 60653

And here's what the back of the lump looks like.

View attachment 60654

I'm 99.99% sure it would have had a solenoid hooked to it just like your other dump valves. Any big hunks of tape hanging around that look like a solenoid by-passed?

Sure does look like the same lump. I'll take another look at it, maybe it's been modified but I'd swear there was no solenoid on it!:beatsme

 

[OFF]

Anybody who might be interested in a 40F manual set for the price of postage, send me a PM.