Different Differential



Get the gear

I am basically tipping my hat to the hobby engineers out there. Somewhere along the way I needed a ‘universal joint’ but research efforts far outweighed practical knowledge. This post acknowledges those that inhabit the world of, wait for it… gears.

Hypothetical gear config @ 60 degrees:


and a nice write up on gears:


To bevel or not to bevel

In my research I came across some confusion in terminology (or probably my own). While mitre gears (or miter) fall into the category of bevel gears – gears of various angles – the term denotes a motion transfer of 90 degrees.


Some instances of rotation require antithetical movement such as counter rotation.

So what is the application for this type of gearing I hear you ask ?

Well, as Beatty Robotics outlined, NASA employs a similar setup for their Mars Rover to enable mobility over rocky terrain (beatty-robotics.com). And check out Beatty’s own fab counter rotation differential.

So here is my build for a similar axle. Needing a prototype setup to try things out I used adjustable parts such as bearings mounts, spacers, collars etc before constructing the 3 geared version. Casings, blocks and collars are aluminium.

Take your camera to the Tour Down Under


Lining up

Stage three of the Tour Down Under is an exciting and immersive experience filled with a heady mix of high tech machines and physicality.

The TDU is now fifteen years old and that a city should embrace cycling with such commitment and vitality is testimony to its success. Similarly, other festival cities such as Monaco and Edinburgh seem to share a mix of community and festive spirit that is perhaps the envy of larger cities.

Stage three begins at Norwood in the city with a challenging race distance of 143.2 km ending at Paracombe nestled in the Adelaide Hills. But the competitors are all smiles and easy charm as they breeze past the media throng taking it ‘in their stride’. Their attention is fleeting as they prepare themselves slowly circling on carbon fibre technology and congregating at the start line. And in a blink of an eye the cyclists are already pacing away followed up by the team cars and support crew. Its a beautiful, festive sight and the buoyant crowd is anticipating a tremendous marathon race.

Big bike

Ironically the first english speaking World Tour stage race, the TDU has rapidly gained world attention for its combination of superstars as well as the cream of Australian Cycling. 2015 marks the final Tour for champion cyclist Cadel Evans. Since its beginning in 1999, the race has grown from relatively obscurity to an impressive international event with a television audience of many millions. It is a six day event with various stages and cyclists competing for the coveted Ochre Jersey. Part of the success of the Tour has to do with its uniqueness (aside from its considerable organisation and sponsorship): the rolling hills and sunny aspect (a welcome relief from Northern Hemisphere winter) has exciting finishes demanding sprints and drawing big crowds in finishing towns. The other is the winding course through regional settlements and wineries strikingly similar to their race counterparts (Southern France, Spain et el).

Richie Porte


It is not surprising that all-out sprinters such as Andre Greipel are so suited to TDU winning eleven stages. Finally and not least, the Tour’s success has to do with the city’s enthusiasm and embracing it with a zeal that has as much to with its fanatical and genuine cycle culture as its inherent festival culture. The Bupa Stage Four of the TDU attracts thousand of recreational participants. It is also not surprising the TDU is contributing to the rise of the sport in this country and enabling it to become one of the strongest cycling nations.



(1) http://en.wikipedia.org/wiki/Tour_Down_Under

(2) ‘A brief history of the Tour Down Under’ by Duncan Palmer


(3) Nikon DSLR camera


Team backup
Giant inflatable
Santos rep
Orica GreenEdge