Small Grapple Boom...

[/pine]

I have not done any recent searches since I first had the notion to build a small hydraulic knuckle boom mostly for logs and firewood work...

I've been thinking more and more about it (mostly as a labor/pain saver) more and more lately...

As originally encountered the first major obstacle is a rotating base...lots of ways to do it but I'm looking for the least complicated and low cost...
The plan is to make it so a 3 PH can hold it or it can be mounted on a trailer or truck bed etc...

I'm not looking for a commercial swivel base...I'm looking for a DIY solution...any ideas ?

 

[ericm979]

Could you use a trailer axle (cut or purchased stub) and hub? Or is that not going to be strong enough?

 

[bcp]

If only about 180 degrees rotation, copy a backhoe.

If 360 degrees, try a trailer axle stub and hub. If heavy duty needed, a truck wrecking yard is likely to have a bent or broken semi-trailer or drive axle end and hub.

Bruce

 

[/pine]

Yeah 180* is good...Sorry I didn't clarify...what I'm seeking ideas for is what moves the swivel of the boom...I have looked at some backhoes but most are more sophisticated than I would need and some would require having some parts machined etc...

Electric (12V) offers both pros and cons but I have not ruled it out...especially if I could just use a couple of generic starter motors and a flywheel...a rocker switch is cheaper than another two SCVs...

 

[bcp]

I think a starter-flywheel system would be much too fast.

From:

Starter Drives Explained

North Atlantic Starter Drive,We Specialize In Customized Rebuiding of Starter Drives and Starters,Domestic and Foreign

northatlan.com

=================
Normal cranking speed for the engine is about 200 rpm.
==================

3+ rpms per second

Bruce

 

[/pine]

Including a gear reducer/increaser would not be too difficult but getting a bendix to work with the gear box is another issue...using a chain and sprockets is another way to go...

 

[GLyford]

For 180-270 swing, some designs use a cylinder to move a chunk of 50? 60? chain past a sprocket. Some use the length of chain straight along a length of steel angle or channel, like a rack and pinion, others make most of a loop of chain and a 2nd sprocket, and pin the loose chain ends to a traveler or tensioner, that also has a mount for one end of the cylinder.

Some of the guys that make their own snowblower chute swing assemblies may have ideas you could steal, like a length of cable that goes to a winch, which is bolted to the pivoting piece with a keeper, and enough wraps of cable above and below that for the desired amount of swing.

There are patterns (or maybe pattern generators, I forget) out on the web for making templates for making any size sprocket of your own, so you could make a "ring" sprocket for the swing, then make a much smaller pinion out of two regular sprockets the same size, stacked, with pins welded to both, to push on your ring socket. Or maybe use one half of a chain shaft coupler and use it to run on the ring sprocket. Chain Couplers | Shaft Couplers | Power Transmission | www.surpluscenter.com (I am spitballing, I don't know how well that would work).

 

[i7win7]

something like a p/u boom host?

Maybe a commercial truck junkyard has some utility co. trucks.

 

[/pine]

I'll be using a similar (ground) engine lift to start with...

 

[/pine]

...Side loading collapses cranes and hoist. Careful with rotation. First rule in crane training, never side load. Cranes are not winches. ...

One of the first things I learned on the job as a field engineer employed by the contractor and owned all the cranes...was the top of the boom (or wherever the load extended from) was to be plumb over the destination or load hook etc. target...

We did a lot of work in the blind and voice over radio and hand signals were paramount...whenever someone is giving directions to a crane operator they are letting him know which way the boom needs to move so the cable etc. will be plumb...

To get an idea of the concept...see the link:

Logging trailer with crane 3T ATV log trailer tractor (HFT-3000) CE | eBay

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