Jib Crane Tie Rod

[AEng123]

Hello,

I am designing a tie rod for a wall mounted jib crane. I have attached a Spanco drawing of a similar design.

My question is: do I need to make room for a wrench for the nut that sits between the tie rod clevis plates? Or is it just hand tightened during the adjustments during install?

I searched for videos or instruction manual for tie rods but what not able to find anything that showed how these actually get installed.

Thanks you,

A.M.

 

[JStephen]

Never dealt with one- I would think you either need to turn the nut after it's all assembled or else use threaded rod with opposite-threaded ends and make it where the nuts can't be turned- like a turnbuckle. Room for a socket might be adequate.

 

[oldestguy]

I'd use a turnbuckle and both right and left hand "bolts" at each hinge, welded in. Much less "stuff" to deal with. You never know if some day you move it to new location and it needs re-setting the rod length. Maybe another way: Weld a not or bolt on one end of the rod to fit inside the "U" shaped hinge and weld it there. On the other end of the rod weld a left hand threaded rod or bolt for for the turnbuckle. The far hinge would have a right hand threaded bolt or threaded rod welded in.

 

[hokie66]

I think the rod itself is a long turnbuckle, with right hand threads one end, left hand the other. You turn the whole rod to level or otherwise. The nut in the clevis is fixed in position.

Could be done in different ways, but I understand that is the typical way.

 

[rb1957]

yes, the nut should jam in the clevis and the whole tie-rod is effectively a turnbuckle. Watch that you don't undo the trapped nut.

If you find that the nut is turning a bit inside the clevis, add a packer to the inside of the clevis to reduce the clearance. This'll also help wearing on the clevis.

another day in paradise, or is paradise one day closer ?

 

[AEng123]

Thank you everyone for replying, makes sense now.

 

[MikeHalloran]

Within the world of British motorcycles, when there were British motorcycles, the turnbuckle with right/left threads was called a Johnson Rod. They were typically used for connecting the foot-shift bellcrank to the operating lever on the transmission.

They were despised for loosening from vibration, even when equipped with jam nuts, and for then literally falling off along the road, or worse, bouncing up and snagging a spoke. The Johnson Rod is one major contributor to the disappearance of the British motorcycle industry.

The Japanese used them on their motorycles, too, but with elastic stop nuts or thread locking compound, and that made all the difference.

As for finger tight, no, nobody wants that; you need wrench clearance around every polygon that is not being held captive by its geometry, and you need some kind of Loctite on every thread, and probably jam nuts, too. Jam nuts by themselves will someday loosen from vibration or impact, and nobody except some lawyers will be happy when that causes the jib to fall.





Mike Halloran
Pembroke Pines, FL, USA