Interview with Norman Hossack for carbibles.com

[r1 Convert]

The chap who invented the Duo Lever

I set out to bring some new thinking to motorcycle design. I had left McLaren with a wealth of experience seeing how racing cars developed and how Formula 1 addressed their technical problems. I was only a spectator in the motorcycle industry and had no connections with it and still don't; I don't even ride a bike. I do own the first Hossack BMW (see the picture on the right) but can't ride it where I live because the EPA think German carbon monoxide is worse than American carbon monoxide.
Back in the mid 70's, from where I stood, motorcycle design problems were obvious and easily solved. Just improve the rigidity, lower the weight, lower the polar moment, and kill stiction. So I did that and it worked, and it won races and then it won again and again. Job done! No! I didn't count on the inertia and negativism in that industry. Seems perceptions are more difficult to change than the engineering.
What has become known as the Hossack suspension system, I chose from a list of about 5 designs options that I had invented. I assessed this one was the one that my meager resources could do justice to. The other would have required expensive tooling and structures and didn't take things that much further forward. I am not talking here about simple material changes; making the same thing from aluminum or carbon fiber does not constitute a new invention.
To look at the fundamentals of my design there are some first principal elements to study.

Lower weight. A bar bending between fulcrums suffers a pure bending load. However if the load wasn't strictly bending, but straight push and pull, it could carry a load thousands of time higher. This higher value can be exploited with triangulation. Race car wishbones are an excellent example. These little devices can carry thousands of times their own weight and have near total rigidity. Everything on my design is triangulated and with that added strength you have a chance to save weight.
If you were able to look down the axis of the steering on my design you would see that the weight was quite close to the pivot axis. This means low polar moment and this is important because most forms of weave are sustained by this mass. The further it is from the axis the greater the chance it can add to weave.
Low stiction allows the tyre to ride bumps in with out being bullied by the suspension this is where grip come from. You will commonly hear commentators say 'mechanical grip' in F1 events and that's what I am talking about here.
Tellies (telescopic forks) turn brake loads into dive, and dive limits free wheel movement. My system doesn't do that and allows full and free movement even while braking. But more when a tyre is stopped too hard and it loses traction, the energy stored in the front spring of a telescopic system is suddenly released and it punches the tyre further making the chance of regaining traction nearly impossible. Vernon Glasier on HOSSACK1, my first bike, could readily slide the front wheel and still regain traction.
So the fundamentals are there for discussion and challenge. But whether I managed to get it right first time with only my meager resources is in question. Though as a comment on my design it is worth noting that Hossack1 won its last championship in 1988 at which point it was 10 years old. Could I have done better? You betcha! I never built a bike with a real race engine and never found funding to do it the way it should have been done.
So my attempt to revolutionize motorcycle design was a nonstarter in the environment it was born in and I had to wait nearly quarter a century to see the idea reach production (the K1200S) leaving me out in the cold as patents don't last that long.
I wonder when the next manufacturer will take it up and exploit the areas that BMW didn't.

Norman Hossack.



Read more: http://www.carbibles.com/suspension_bib ... z1aNaKl33N

[thebigblue]

Thx for sharing - well spotted