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Zero Backlash Universal Joints

Zero Backlash Universal Joints

Zero Backlash Universal Joints

(OP)
I'm looking to incorporate a small (12-15mm OD) u-joint with little or no backlash. It would need to operate at >=20 degrees around 10RPM. In my industry, we manufacture almost everything unless it's made by an approved vendor, which is an exhausting process. I've found the attached u-joint, but can't figure out how it's made or how to design something similar. Any thoughts on alternative designs or how these are made?

RE: Zero Backlash Universal Joints

You have to consider the rest of the hardware in the drive line, not just the joints. Splines and other couplings will add backlash.

RE: Zero Backlash Universal Joints

(OP)
Update: the outer ring is definitely made of two plates welded together.
@Swall - I'm actually more concerned with translation in the u-joint than rotational backlash.

RE: Zero Backlash Universal Joints

The scale might be unusual, but disk couplings are clearance-free, torsionally and radially stiff. I'm not sure, but your "backlash" might be radial stiffness and zero clearance?

For low torque I wonder how a piece of rubber hose would work.

RE: Zero Backlash Universal Joints

At +/- 20 degrees angularity, you might consider a flexible shaft

RE: Zero Backlash Universal Joints

(OP)
There is a relatively large axial load and the position of the shaft must be precise. I fear that any flexure joint or flexible shaft would allow for too much translation of the shaft. Thoughts?

RE: Zero Backlash Universal Joints

Applying a large axial load to one half of a u-joint with significant angulation, as in this case, develops a relatively large radial load on the opposite half's ear, and a significant thrust load on the related leg of the cross.  Most commercial u-joints are designed for relatively small radial loads, and will exhibit significant deflection and wear when so misapplied.

I.e., if I am understanding your loading case correctly, you will be better off developing a custom solution from scratch than copying someone else's design that you do not understand.

 

Mike Halloran
Pembroke Pines, FL, USA

RE: Zero Backlash Universal Joints

Along the lines of rubber hose - a metal bellows (e.g. Servometer) can pass a heck of a lot of torque.  The advantages of such devices are they don't have the fluctuating rotation (2x/rev) that a cardan joint gives.

RE: Zero Backlash Universal Joints

oh, and my other point - true zero backlash, no bearings/joints to wear and start to develop increasing backlash over time.

RE: Zero Backlash Universal Joints

(OP)
life span is not an issue, as it's an expensive disposable part. The duty cycle will be extremely low - something like 300 revolutions.

RE: Zero Backlash Universal Joints

(OP)
I don't need constant velocity.

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