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The JLG 40F Boom Lift Dilemma

OFF

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Sep 30, 2009
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HD Mechanic
Hey Rick39,
Glad to have you on board.

Hi Barr, good to see you. Do you know the flow divider valve that splits off into the pilot pressure line to the Bertea bank Rick39 is talking about?
 

Rick39

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Jan 6, 2017
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Location
SE PA
Yes, that's it.

The pilot flow goes into the side of the stack on the inside. The fitting in the valve has a screen behind it.

Above that fitting on the valve is a relief valve for the pilot section, don't remember the pressure but around 300 psi or so.

JLG specified a flow to the pilot section but most people used pressure to set the divider valve.

I used to turn the adjustment in, then slowly out until the engine sounded like it had a slight load on it.

The dump valve has to be closed, so start from the ground controls and make sure it operates from the overrides before adjusting.

Make sure the pilot valves have a signal, best to check milliamps on one of the wires going to the pilot valve.

Don't remember the value, but maybe 500 ma at full stroke?
 

OFF

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HD Mechanic
The pilot flow goes into the side of the stack on the inside. The fitting in the valve has a screen behind it.

Above that fitting on the valve is a relief valve for the pilot section, don't remember the pressure but around 300 psi or so.

JLG specified a flow to the pilot section but most people used pressure to set the divider valve.

I used to turn the adjustment in, then slowly out until the engine sounded like it had a slight load on it.

The dump valve has to be closed, so start from the ground controls and make sure it operates from the overrides before adjusting.

Make sure the pilot valves have a signal, best to check milliamps on one of the wires going to the pilot valve.

Don't remember the value, but maybe 500 ma at full stroke?

Thank you sir! :notworthy
 

dn29626

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It has been mentioned before in this thread...a quick search overlooked it...what degree grade can these JLG 40 F machines climb?
 

OFF

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It has been mentioned before in this thread...a quick search overlooked it...what degree grade can these JLG 40 F machines climb?

The manual doesn't give a spec that I can find, but from what I remember the climb angle is not that great. You may want to get a winch to help it along. A 40F will not climb like a modern 4wd machine will. No where near it.
Low drive, and high engine is what you want to be climbing in.
 

Rick39

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Officially the 40-45 and 40F had to be mechanically assisted on grades exceeding 20% (roughly 9 degrees).

In the real world, 20% is about the angle of a rollback deck and few if any would climb it without being winched.

On a good day with 254 motors maybe 15% would be possible.

What really made the units climb was when they went to piston drive motors in the H models. Double the horsepower didn't hurt either!

OFF is exactly right, climb in high engine low drive.
 

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dn29626

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OFF & Rick39, thank you for the quick answers.
For loading on a dovetail gooseneck trailer, a 4 foot vs 5 foot dove may not matter then.
(I asked this question more directly on another thread I started here at HEF and got no response.)
BTW High engine, low drive is the way I load.
I found a 30 foot, 14000 GVWR trailer, I am considering buying. 26 foot flat, plus a 4 foot dove.
 
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dn29626

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Well, no one has expressed concern that the 40 F will overload a 14000 GVWR trailer.
I will take that as good news to move forward with a 14000 GVWR trailer purchase.
 
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Rick39

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Well, no one has expressed concern that the 40 F will overload a 14000 GVWR trailer.
I will take that as good news to move forward with a 14000 GVWR trailer purchase.

That depends on the empty weight of the trailer, if the unit you have is actually a 40F (a few units on this thread thought of as 40F's are not), and the configuration of your JLG.

An older unit with no platform rotator and a 5' platform will be a bit lighter than if it has a rotator and an 8' platform.

Not only are the components on the platform end heavier but they necessitated heavier counterweighting and in some cases extra weights on frame sides.

Also consider that the unit is fairly long which limits how it can be positioned on the trailer in order to axle the load properly.

Too many variables to make a judgment from behind a keyboard.
 

dn29626

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...the empty weight of the trailer?...
...if the unit you have is actually a 40F...
...the configuration of your JLG...
...consider that the unit is fairly long which limits how it can be positioned...
...many variables...
Rick39. Thanks for commenting. My JLG still has 40F on the boom.
My reasoning in the 30' trailer is better control in positioning some of the weight onto my truck.
The platform can be placed over the neck or at the dove, whichever gives me the best balance.
I figure with no one expressing overload concerns (since 1/17/17) , the load is acceptable.

**EDIT I just finished a weight balance search.**
**20 to 25 percent of my load will be on the truck, so the 14000 GVWR is plenty for the 40F.**
 
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Catz4

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Burlington, Iowa 52601
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Metal Faberication Addison Mechanical
No problem arjaytee. I will begin sending them as I get a chance tonight. They will be in multiple emails so the size doesn't cause a problem in sending them. :)
Would it be possible to get a copy of Schematics,Parts Manuals for JLG40F. I'm a proud new owner of one. not sure on pump type yet ,was running 5yrs. ago . It's in good shape, 1287hrs. on it, there's very little wear on the machine. Been sitting outside in grass frame on ground. wanting to get to know more about it before i start it ,and get it dug out of ground . Thanks Paul.
 

OFF

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Hello, and welcome Catz4! Hopefully the tires are ok on your "sunken treasure". Tires tend to rot when they are left un-inflated for long periods of time. That size rubber is getting really hard to find these days.
Get in one more post to unlock the private message feature, then send me and email address that I can send the manuals to.
 

Catz4

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Burlington, Iowa 52601
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Metal Faberication Addison Mechanical
Hello, and welcome Catz4! Hopefully the tires are ok on your "sunken treasure". Tires tend to rot when they are left un-inflated for long periods of time. That size rubber is getting really hard to find these days.
Get in one more post to unlock the private message feature, then send me and email address that I can send the manuals to.
Thanks Hello yes tires are going to have to be replaced they are rotted to bad, they have tread large cracks not safe to use. Maybe next week get it dug out back at shop to see what I've gotten into.
 

Austin022

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Mar 6, 2017
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Location
Kentucky
I'm gonna apologize in advance if this question has been asked because this forum is long as can be. But can anyone point me in the direction of parts for a 40F sn736017? Specifically swivel motor parts. Need oil seals in gland nut badly. And possible a back up motor. Thanks in advance.
 

Catz4

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Burlington, Iowa 52601
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Have 40F home now comes TLC !
 

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