On May 17, 8:37*pm, Ignoramus31865 ignoramus31...@NOSPAM.
31865.invalid wrote:
I have a GM 3/4 ton pickup.
...
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

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/r...s/HPIM0470.jpg
http://www.collectorcarsforsale.com/...0718522101.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