Zero Backlash Universal Joints

[brdaaw]

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?

 

[swall]

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

 

[brdaaw]

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.

 

[Tmoose]

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.

 

[sreid]

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

 

[brdaaw]

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?

 

[MikeHalloran]

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

 

[btrueblood]

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.

 

[btrueblood]

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

 

[brdaaw]

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

 

[gadkinsj]

Do you require constant velocity?
I have had good luck with Flexible drive shafts similar to this.

http://www.mcmaster.com/#flexible-drive-shafts/=evkgsx

 

[brdaaw]

I don't need constant velocity.

 

[asimpson]

http://www.zero-max.com/flexible-shaft-couplings-schmidt-couplings-c-1_8-l-en.html