Comments on: Hemisphere Drive Speedster (Oct, 1938)

By: blast

blast — Sat, 09 Jul 2011 14:11:04 +0000

Just announced a few days ago, after having been re-invented:

http://spectrum.ieee.org/autom.....his-before

Congratulations, Curtis Boirum. That’s a really cool design. Don’t you hate it when it turns out “there’s nothing new under the sun,” though?

By: Gary

Gary — Wed, 15 Oct 2008 00:37:11 +0000

I love the comment that with a 600HP aero engine incredible speeds could be achieved. I think that tends to apply regardless of the manner in which it applies traction! Dreaming about 600hp cars……

By: Orv

Orv — Thu, 01 Nov 2007 03:10:44 +0000

Some lawnmowers use a design that’s similar in concept, but with two perpendicular discs instead of a hemisphere. The farther out from the center one disc contacts the other, the higher the effective gear ratio.

By: Rick Auricchio

Rick Auricchio — Thu, 13 Sep 2007 18:58:43 +0000

Interesting. What he’s developed is essentially a continuously-vaiable transmission.

The photo shows the hemisphere in no-motion state (though I wonder if it simply scrapes its apex on the pavement!)

As one side of the sphere is lifted, a circular section makes contact, moving the vehicle. Lift farther and the contact circle becomes larger, speeding up the vehicle.

This is analogous to using gears of different sizes to create different speeds. Think of the sphere as a gear (pinion) and the road as a flat gear (a rack). As you roll the sphere/gear, you move along the road. When you make the pinion larger (by tilting to get a larger section of the sphere into road contact) you move faster.

This idea may have ended up in some mechanical designs, but we know it’s never been used as shown.