i have to build a tripod hoist crane height under hook 12 feet reach 2 tons as realizable, can you help me? thank

http://www.arrow-cranehoist.com/tripod.htm

http://www.cisco-eagle.com/catalog/c-5329-tripod-cranes.aspx

What are the sides of the triangle base?  What will it be sitting on?  (dirt, rock, pavement)      Engineering data depends on dimensions and angles.

That looks like 4" pipe, 

I agree Charles   I really don't see his problem. That basic design  is almost universal.   The only question is how long the legs.  Which is determined by the base triangle.  And the height to be lifted + the lifting gear (hoist, hooks, attachments, top joint pieces.)  The tables seem to provide everything he needs with out any calculation. set it up and go. The top fixture would need some serious fabrication but within the range of any professional weldor.

I believe his need for help is a lack of practical building experience. Hence the lack of pertinent details.

He has height and weight. The surface it's going to be on is IMPORTANT, so is the WIDTH of the tripod at it's base.

I don't even consider a tripod for unloading vehicles, only for straight lifting as shown in the picture where one is mounted over a well.

A swingset / A frame hoist if far more efficient, can be mounted on wheels and or knocked down for storage. About half again as much steel but far more useful.

Frosty The Lucky.

 

Greetings Angiolino,

You could build 2 as pictured and add a cross beam . All would collapse and be portable. This would allow offloading trucks and trailers 

Forge on and make beautiful things

Jim

That looks like 4" pipe, 

I forget how to do the exact calculations, but bending/ buckling is going to be the big factor in this. It's member length / diameter and then the stiffness/resistance to buckling comes into play. That's why you can stand on a 12" 2x4 stood on end with no problems, but try the same thing on a 12' 2x4 and it snaps in half and collapses.  Larger diameter is usually stiffer than heavier wall thickness.

 

one other thing to take note of is the tension members shown at ground level in that picture. That will keep the legs from splaying out under load. With a load of 2 tons, I wouldn't count on ground contact alone to stop the legs from splaying. the tension members will be critical.

First link has the measurements.  Second has where to measure from.

Seems pretty straight forward to me.  Maybe the OP will come back and give more information.

Edited October 24, 201510 yr by natenaaron

I have worked with the aluminum ones with fire/rescue in AZ. Chains work just fine keeping them from spredding. Sandbags or spikes are a pluss. 

I wouldn't even pretend to touch that job without plans from an engineer and a $1M umbrella insurance policy.

thanks guys lighthouse treasure your valuable advice, I have to rest on the frame of the ground campaign as lifting device usero peranco Manual chain

http://www.optimalhandling.com/ShowImage.axd?id=1116&W=207&H=208

 

http://www.sdms.co.uk/images/sized/images/products/SE218-EOD-Tripod_261_400_s_100_imagesproductssdmswatermarkurl.png_100_100_60_c_c.jpg

OUCH !!!   WHAT'S ???    keeping the feet from moving -- further apart or spreading ???

looks like a nice BIG barn though