Need help with torque reactions!

[jus2sho]

Hi,

I have 2 cylinders with a right hand tapped hole on each end. The 2 cylinders will be joined with a coupler. When operating, the rotation will be clockwise with a constant tension downwards. I believe right hand threads is correct because it will constantly tighten the three pieces together with a clockwise rotation. Can someone show me the reaction moments on the ends of each piece? Thanks in advance!

 

[jus2sho]

Sorry. I attached a blank file.

 

[tbuelna]

If the upper and lower cylinders are constrained from rotating, and the thread pitch of both threaded connections is the same, then rotating the coupling will not result in any net vertical movement of either cylinder. If the upper and lower cylinders are constrained from rotating, then the torque reaction produced on them will be equal to the wrenching torque applied to the coupler.

If you want the upper and lower cylinders to move closer or further apart when you turn the coupler, you need to use opposite handed (LH/RH) threads on the two ends of the coupler, or you need to use different pitch threads on the two ends of the coupler.

Hope that helps.
Terry

 

[desertfox]

Hi jus2sho

I can see both the threads tightening while turning clockwise provided that there is a torque reaction at one end of the cylinder opposite to the driving torque supplied to the other half of the cylinder, however what is generating the downward tensile force you mention?

 

[Tmoose]

If all the pieces rotate together I'd say the torque at any slice along the well aligned assembly will be the same as the torque reaction at the output end.
Minus any windage resistance or rubbing etc.

What happens when the power is cut?
Will it stop real quick due to the output resistance ? Will the driver's tendency to come to a stop slow down the assembly?
Torque would be reversed in the second case.

 

[TheTick]

Turnbuckles use couplers with RH thread on one end and LH thread on the other.

 

[chicopee]

You should tell us more about the device in order for us to show you the moment reaction and the reaction to the force whether it's frictional or caused by the inertia of the cylinders and coupler or by an opposite force at the end of the upper cylinder. Describe the device and its operation, otherwise we are just guessing.

 

[rb1957]

"Turnbuckles use couplers with RH thread on one end and LH thread on the other."

yes, i thought about that when this thread started, but turnbuckles are trying to tighten the cable they're attached to, so they have opposite threads so the ends move in opposite directions, tightening or loosening the cable. if they had the same thread you'd just be letting teh barrel migrate along the cable.

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