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Is this going to get me killed?


DirtyComanche
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So, say a guy wants a little crane on his POS farm truck.

 

Obviously, he could just go out and buy something. But, that'd be boring.

 

So, I'd like to build one. Of course, like most things I build, I do consider the possibility, or likelihood, of death.

 

So, MS paint of what I'd like (don't hate my MS paint skillz, girls)

 

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It'd be about 4' tall, and the boom would be say 42" - 72" measured from the pivot to the choker. The base would be say 12"x12", and the pipe (yes pipe) would be say 3.5" sch40. The pivot would be an upside down trailer spindle/hub assembly welded into the pipe. I am slightly concerned by doing this, and hope I can find a big enough spindle/hub to feel comfortable. To service it, one would have to unbolt the crane at the base plate. More pipe would make the upright to the pivot for the boom. A PA hydro cylinder (jack type) would be used to raise/lower the boom like any old engine hoist. The boom would be perhaps 3.5" sch 40 with 3" sch 40 inside it to allow for length adjustment. I'd run some tube over top of the boom for strength, like is done with flat bar on engine hoists and such.

 

I only want to lift say 800lbs with the boom retracted, less with it extended... Think it'd all be up to the task? Or, am I building something to kill myself with?

 

Oh, I'm aware I need to bolt it to the frame of the truck, the box isn't strong enough.

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Probably should be fine as long as you came make sure the pivot is strong enough.

 

I seem to remember some redneck pic of an engine hoist in the back of a truck being used as a tow truck...

 

Do you need it to have full 360 degree rotation, or would you be fine with only having, say, 3 positions for it to be in? Straight back, left and right.. etc.

 

If you can make set points, then you could probably make a reinforcment bar going to the floor of the bed. Something like this.

 

 

:dunno:

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It has to be able to pick it up and rotate. I'd only be using it for loading random stuff into/out of the truck. You know, axles, engines, building materials and etc...

 

I've seen the pic you're talking about. I think the hoist was only ratchet strapped into the truck bed... Very hack.

 

 

Pong, there ain't no northern tool up here. Besides, the ones that they sell (if they're like all the other ones on the internet) have a pathetically short boom. Like, 40" full extension with a 500lb rating!

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just take an engine hoist, cut off the bottom weld it to a rotating platform, and you got yourself a rotating crane, or at least use an engine hoist as help make a design

 

 

Well, this design is probably totally sound. It's just a rip-off on an established design for a rotating jib crane for a truck, but with much beefier materials (4"x.220"~ pipe as opposed to the cheap 3x3x.188 (if that) HSS that is used). The pipe part is okay, I know which grade to buy. My main concern was the usage of a spindle/hub assembly from a vehicle or trailer for the rotating part. I have confirmed empirically that if I use a 14 bolt setup it will be totally fine, so any 1-ton+ rear axle or 1-ton+ trailer axle setup should be fine.

 

I'm building one instead of buying one for a couple reasons. I like building things is one of them... My time is split between locations, and I can't work on my jeep most of the time. But my farm truck, it is here, and I can work on it. Also, nothing I've found for sale is actually built in a way that I'm happy with. Everything reeks of cheap imported junk. I'd like to show you the pics of an engine hoist that folded while at the 1.5T setting, it was only lifting a SBC and TH-400 (no where NEAR max load). Besides, I don't think I'd be money ahead going that way anyways. I think I payed about $250 for my engine hoist (which is a cheap chinese POS), it would still need to be modified extensively to work for this.

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Is it gonna be mounted on some type of rails? to slide back and forth in the bed? I'm just thinking that if you hoist something from the ground it will still be over the ground, not the bed of the truck. Probally easier to roll the whole hoist back then to try and push in the extended boom with a heavy load on it.

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Is it gonna be mounted on some type of rails? to slide back and forth in the bed? I'm just thinking that if you hoist something from the ground it will still be over the ground, not the bed of the truck. Probally easier to roll the whole hoist back then to try and push in the extended boom with a heavy load on it.

 

 

Nah, mount it solid behind the cab, offset to the driver's side. Or at end of the bed, offset again. The length of the boom is so that you can pick up a load and set it in the bed by rotating the crane (bed is 8' long). Positioning the truck relative to the load will be critical. I wanted to make the boom length adjustable in use, via another jack/cylinder, but it would be a huge PITA unless I had a power pack or PTO driven hydraulic setup as it would take an absurd number of pumps to extend/retract the boom... Although, maybe I could get a jack that would work for that (rated for less weight). Rails would be kinda cool, but another complication. And it should swing easy enough (hence the spindle) as long as it's reasonably level. If it isn't, it'll go to the low spot. I'm not too worried, I should just be able to grab the boom and pull it over, and failing that I can do so with a rope and pulley. None of the commercially available ones have anything to aid in swinging them, nor any means of adjusting boom length while in use.

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Besides, the ones that they sell (if they're like all the other ones on the internet) have a pathetically short boom. Like, 40" full extension with a 500lb rating!

 

 

That might have more to do with the fact that they are being bolted to a truck bed. Not exactly the sort of base I would suggest for the huge force that the crane will effect on it.

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the reason that typical bed lifts only have a 40" extension on the boom is that they reside at bed rail height...they operate at very extreme angles (i.e. boom extends to over 90 degrees from the center point of the pivot) to do so, but keeping the base that low helps reinforce the mounting points to the bed, as my grandpa explained it to me. he has one in every one of his construction trucks, and they use them regularly for a variety of equipment...very convenient, and pretty safe.

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