Securing gears on shafts

[Dan Petrovic]

What you might want to look into in the future are keyless hubs (or that's what we called them).

They are kind of expensive and they can get pretty heavy, but we didn't have a single key for all of the round shafts we had this year.

We lifted trackballs with our arm with no slippage. Some of these keyless hubs are rated for absurd amounts of torque (for our application). Somewhere in the neighborhood of 700 foot-pounds, I think.

http://www.globalspec.com/FeaturedPr...54/0?deframe=1

It's kind of hard to explain, but there are two parts to each hub. An outer part and an inner part (the inner part is connected to the flange you see on the right-most surface. Each flange has a barrel sort of section with slots in it. The inner barrel has a taper on the outside of it, and the outer barrel has a taper on the inside.

The holes in the left flange are tapped, so when you tighten the bolts the flanges are pressed together. When the flanges are pressed together, the inner barrel is pressed farther into the outer barrel, causing the inner barrel to be squeezed inwards, clamping onto the shaft. The outer barrel "blooms" outwards, clamping onto the inside of whatever you're trying to get to spin with the shaft.

One thing to remember: You have to have very tolerances for this too work. If the hole in the gear (or whatever) is a tiny bit too large, then the hub wont clamp onto the gear. If the shaft is a tiny bit too small (I'm talking ten thousandths of an inch), then the hub wont clamp onto the shaft.

These things are very easy to use and if you do it properly, you wont have to worry them slipping.