'Threadless' leadscrew

Many years ago i worked on a CMM that had 'leadscrews' that were round bars that had a nut consisting of 3 roller bearings set at a shallow angle to the bar. As the bar rotated the nut travelled along the bar.

A colleague of mine used to call then a ewin / euan / uwin drive but google doesnt seem to know about them.

Anyone cast any light on this?

Will this do, Paul ?

**LINK**

https://www.researchgate.net/figure/Concept-2-An-angled-traction-drive-where-the-rollers-are-not-mounted-parallel-to-an_fig1_265509008

The source document is interesting, even though it’s a little off-topic.

MichaelG.

Seem to show up in 3D printers *** LINK ***

Principle can be seen in photo where bearings are on the skew.

John

Edit: Spelling

Edited By Journeyman on 08/03/2020 12:02:07

That's the Badger!

Its a simple cheap and effective solution.

It appears the correct term is uhing (seen here from the link in Journeyman's post).

Thank you for the info.

I saw one of those in 1987, back when brushless dc motors were not commonplace (our company were specialising in prototypes). It was to be used for some kind of sub-sea monitoring system in the oil industry.

Uhing units were cheaper way of winding wire onto reels used as a traverse unit left and right but could only be used on light wire as lack torque proved an issue, input speed was constant with variable pitch adjustment and no need for reverse.

We tried a couple but not man enough for heavy work and stayed with left/right leadscrews or leadscrews with fwd/rev clutches.

There is a similar system applied to wheels. Barrel shaped rollers are attached in chevrons, like traction engine strakes, opposite sides are opposite hand. Then by selectively driving the wheels forward and/or backwards you can make the chassis go forward, backwards, sideways, rotate on the spot. It all looks a bit bizarre. See

mecanum

and

movie