Rotation lockout mechanism ideas

[beegw]

I was looking for a rotation lockout mechanism. Hold perhaps a 10-20 ft-lb moment. I was looking for something on mcmaster carr but could not find any thing. I am not even sure what you would call it. Something that would be used at a pivot point between two pieces of approximately 1" x 2" aluminum extrusion, and could be adjustable angle. Thanks

 

[unclesyd]

One of the simples is stationary slotted disk with a spring load cam in the handle where you move it to any position and release the spring and the cam on the end of spring slides into a slot. There are many ways to lock this mechanism into position. The two I've seen most are is the besides slot in the disk there are holes to accommodate a lock another is where the mechanism to operate the spring loaded cam on the handle has holes to accomodate a lock to prevent operation. This type mechanism is seen on wafer or disc valves, sometimes on dampers, unloading chutes ,and the old red tractor. One name for this mechanism is quadrant.

Depending on what you are trying to accomplish you might look at throttle arrangements for large boats. These systems lo also lock by detent and are operated by moving the handle to one side to increase or decrease speed. An older throttle has the operating arm rotating about a stationary shaft where the handle is rotated on it's axis to release tension provided by a screw operating against the stationary shaft.

 

[gruntguru]

You might be able to modify the adjusting mechanism from a reclining car seat or a handbrake.

Engineering is the art of creating things you need, from things you can get.

 

[kingnero]

Or a concrete mixer. ( as explained above )

 

[ornerynorsk]

We use rotational locking methods all the time. What determines which method will actually work is this: Do you need infinite adjustment or incremental? If incremental, how fine? Do you need 360 degrees of movement or some lesser range? How rapidly do said adjustments need to be made? Are you OK with slippage when your pre-determined torque values are exceeded, or do you need a "reset" mechanism of sorts, such as a spring latch or even a shear pin?



It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[telecomguy]

How about a "torque" hinge:

http://www.mcmaster.com/#torque-hinges/=cflajj

<tg>

 

[btrueblood]

Are the two extrusions over-lapped or abutting? If abutting, the friction hinge or a variant will work.

If overlapping, use a clamp knob or handle (knob or handle on a threaded stem, engaging a tapped hole on the far piece of extrusion).

 

[beegw]

Thanks, a bunch of good ideas. Application could be over lapped or abutting, so some good possibilities.

 

[unclesyd]

A little more food for thought.

Besides the hand operated lever here is a little different approach to lock rotation using worm gears. If you need something small and with high precision I would check with some one like Rhino Mechanical. If you can tolerate a larger and more robust system you could look at one of the many worm gear valve operators like the FNW.

http://www.rinomechanical.com/pdf/gearboxes/RINO-P_PF_NEMA.pdf

http://www.fnwvalve.com/FNWValve/prodDetail.jsp?BLOCK_ID=1000

0825

I've used the FNW type to tighten and hold brake bans on large deck winches used on Shrimp Boats.

 

[MiketheEngineer]

A big C-clamp??