5000 lbs crane on a 3/4 ton pickup

I have a GM 3/4 ton pickup.
I won, in an auction, a "Ramco RM5000" crane. This crane is similar to the Harbor Freight truck crane, but is a lot beefier.
It is pictured here:
http://igor.chudov.com/tmp/Ramco-RM5000-Truck-Crane.jpg
(not mine, but an identical model).
This is rated for 5k pounds, I am sure for the boom fully retracted.
It has a 8,000 lbs jack. I will put in a longer boom too, and a winch. I am aware that extending the boom will decrease capacity proportionally, so a boom that is 4 foot would decrease capacity of the crane to, say, 1,500 lbs or whatever. I have to call the mfr to find out. This is stillw ay better than my HF crane.
I have a very large 3/4 inch steel plate, I would say 3x4 feet, that is rusting in my backyard.
What I thought of doing, is making a cutout on the plate to fit around a wheel well, and mount it in the back of the truck's bed, and put the crane on top of it. The Ramco crane would sit in the rear right corner of the bed, just like this Harbor Freight crane does now:
http://goo.gl/KAN0Y
It has to be a large plate, to spread the weight of the crane and the levering action that its base would apply to the bed. This particular plate weighs around 300 lbs and is large enough.
My question is, what sort of constraints do I still have. I would hate to overturn my truck, break suspension, etc. I would also think that for heavy lifting, I would need to jack up the right rear wheel too.
Any practical opinions?
i
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Ignoramus31865 wrote:

A crane with that weight capacity really needs to be mounted to the frame, not to pickup bed sheetmetal. I think typically it would be mounted with a beefy bracket under the bed to the frame. A support leg (trailer jack) for the corner of the truck with the crane is common for the heavier cranes so you don't apply a concentrated load to the suspension on one side of the truck and also to stabilize it so it stays level during the lift instead of tilting to that side.
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What I was going to do is put a steel plate, 3x4 feet or so, on the bed and bolt it to the bed. Would that not be enough support for the crane? I already have this plate and it is huge.
i
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wrote:

The bed is probably not more than 18 gauge, right? Plus as soon as you put that plate on top it will rust out fast. Pete is right, also don't weld the bracket to your frame, bolt it.
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The bed is probably 18 gauge, however, it is covered with bedliner.
I will not weld anything to the bed, for sure. Nor will I weld to the frame. This is why I want to use this big steel plate.
i
i
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On Tue, 17 May 2011 21:42:11 -0500, Ignoramus31865

Cut a foot wide strip of the plate and bolt it to the frame on both ends. Weld or bolt the crane to it.
-- It could probably be shown by facts and figures that there is no distinctively native American criminal class except Congress. -- Mark Twain
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typed in rec.crafts.metalworking the following:

    Amazing how flexible truck beds can be. Especially to the torque of an asymmetrical load.

    Oh I don't know, a bed whcih is six inches thick _might_ hold.
    Then again, the whole bed might also just come loose from the frame, from the torque.

--
pyotr filipivich
We will drink no whiskey before its nine.
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Is there mounting plate locations on the Frame underneath ? Attach low and have a hole in the bed going down to the plate.
These almost no frame cars and some trucks might be a nightmare.
Full size trucks have rails for the frame.
Just an idea. Naturally if you have to have the payload area for a load you are then talking about outriders that you plant into the ground (plate under them) to stabilize side loads.
Martin
On 5/21/2011 7:40 PM, pyotr filipivich wrote:

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So, what I think I will do is
1) Use that big 3x4 foot plate 2) For heavy lifts, I would jack the right rear side of the truck.
I will make sure to jack the plate area, to relieve the bed of too much stress.
Make sense?
i
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Ignoramus31865 wrote:

I think you could bracket the crane to the frame along with providing for a swing down trailer jack mounting in that bracket for less added weight than the big plate and faster / easier jacking. It would of course require some design time, cutting parts and welding to make the bracket. A 5k rated trailer jack shouldn't be too expensive.
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Bracketing the crane to the bed is a gargantuan task. I cannot weld to the frame and the area is full of various things.
i
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Ignoramus31865 wrote:

The rest of the truck is just sheet metal, Ig...
--

Richard Lamb
http://www.home.earthlink.net/~cavelamb
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Ignoramus31865 wrote:

It can't be that bad, I fabricated camper mounts for my truck in a couple days that bolt to the frame using existing holes, fit around obstacles and are pretty dang beefy. The main plates that attach to the frame are 3/8" steel plate and the rest is 3/16" wall tube and angle.
I should note that with heavy loads, having things tilt out of level during the lift means difficulty in controlling boom rotation, potentially knocking someone over or pinning them against the truck.
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Instead of dodging sheet metal obstacles perhaps you can replace them with the crane support structure, and bolt it all down to clip nuts on the frame from above like the Ford.
jsw
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Gunner Asch wrote:

Wow, that's a rarity :)
BTW, what are your thoughts on not too expensive optics to use on a flat-top AR (Colt LE6920)?
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On May 17, 8:37pm, Ignoramus31865 <ignoramus31...@NOSPAM. 31865.invalid> wrote:

IIRC my Ranger is rated for half a ton in the bed, at which point the rear springs clear the rubber stops by about the height of a clenched fist (field-expedient measurement). 700 Lbs on the crane, boom retracted and swung to the rear, deflects the spring on its side the same amount due to the increased leverage. Once I had that oak log in the bed the springs deflected a lot less.
I now consider 700 lbs the max to load with the bed-mounted crane. I could position a heavier load close to the bumper but when the weight pulls the bed down the mast tilts back and the boom wants -very- badly to swing out, more than I want to get hurt trying to stop it. I've broken and replaced those rubber stops after pushing the load capacity a little, perhaps due to one-sided spring overcompression from large rocks in the trail.
I made the crane base out of square tubing that bolts through to the frame and then raised the bed level nearly flush with its top with plywood. Unlike a Chevy the Ford's bed bolts down from above:
http://media.photobucket.com/image/recent/redlinesatty/FORD%2520trucks/HPIM0470.jpg
http://www.collectorcarsforsale.com/parts/parts-images-large/1999-oem-ford-ranger-bed-bolts-bolt-clips-83-10_270718522101.jpg
If you pull the bed off you may be able to install stronger crossbeams under it or on the frame to support the crane, without cutting your net load capacity down to my Ranger's by adding 1/4 ton of steel. I peeked under my friends' Chevy and Dodge trucks and a crane mount looked possible, though not as simple as mine. You could make wooden mockups to get the fit right while the bed is still on and the truck not disabled. I've removed the bed perhaps half a dozen times to fix rust or the fuel pump + level sensor assembly.
jsw
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On Tue, 17 May 2011 19:37:43 -0500, Ignoramus31865

That would help you to pop wheelies, Ig.

Just pay closer attention to the same things you already do: centers of gravity, velocity, trajectory, and such. With a jack and heavy object in the back of the bed, your rear axle becomes a pivot at the right weight.

No, maybe brace the frame (or underneath the 3/4" plate) instead?

Wouldn't most heavy things be large and tend to be put onto the trailer via a winch and ramp? What you really need is to sell that crappy old mil trailer you have and get a dropbed dump trailer.
Or for the truck, an extendable bed-mounted ramp with winch at the cab side. Why lift when you can slide?
-- It could probably be shown by facts and figures that there is no distinctively native American criminal class except Congress. -- Mark Twain
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On May 17, 8:37pm, Ignoramus31865

You could put the new crane on a trailer. The trailer could have out rigger supports so the new crane could be used to lift very heavy things with no problems with stability.
Dan
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Guys... I am not talking to anyone specifically right now... I sense a little bit of B/S on this topic.
Right now, I have a crane that lifts 500 lbs, mounted on a 1x1 foot plate, with angle iron underneath the bed holding it in [place with thru bolts. While it is slightly shaky, it works just fine.
With this Ramco crane, I am going to have a crane that would lift about twice more weight -- 1k lbs -- supported by a 3x4 foot plate. That is 12 times more area than the 1x1 foot plate! Even if it is not evenly distributed across the plate, it is still a hell of a lot more support and weight distribution than a 1x1 foot plate.
I think that I will be just fine with it without fabricating any funky adapters and bolting them to the frame.
i
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Ignoramus15557 wrote:

(...)
No fabrication you say?
Ooooo. I *like*: http://www.westernmule.com/spec_sheets/A-1350_Bumper_Crane.html
--Winston
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