| Author | Message | ||
     Kootenay |
Anyone else seen this? (sorry if it's old news here...) http://www.reverserotatingrotors.com/ While I understand what the inventor is trying to do, I have more faith in the simple idea of reducing the rotating mass of the front wheel (as Buell does with the ZTL brake). Extra complexity in a front brake...along with, I assume, extra unsprung weight...I dunno... (Message edited by Kootenay on February 21, 2006) | ||
| Diablobrian |
there is a thread on this over on the XB board. | ||
| Tbolt_pilot |
OK. I got the concept....but where are the pictures!!!! They can't talk about a gee-whiz gadget like that and not even have a sketch for cryin out loud! | ||
| Blake |
It's some kind of monstrosity mechanical nightmare that I cannot make out from the one sketch I saw. A true wast of a patent if you ask me. | ||
| Diablobrian |
It does look a lot like the old Rube Goldberg comics. I certainly don't see savings in unsprung mass.  | ||
| Djkaplan |
There's an interesting example of this concept that was actually raced by Aermacchi/HD in the mid-70's at the Barber Motorsports Museum. It's one of the few items the museum encourages the public to handle and spin. Aermacchi/HD abandoned the concept a long time ago. The benefit of the system must not have been worth the effort at the time. | ||
| Blake |
The huge additional unsprung mass negates the beneficial anti-gyro effect. Meaning, the front end will turn easily, but doesn't handle bumps well. | ||
| Lornce |
Back in the late '70's I talked to Keith Harte a local Ducati tuner/builder who showed me a system on the front end of his NCR based Superbike that contra-rotated the cast iron discs. It used a set of planetary gears in the hub to spin the rotors faster than the wheel speed, so it increased swept area in addition to eliminating gyro-mass. Apparently it also had an anti-dive effect on the front end. His rider, Jeff MacMillan iirc, (pretty hot and eventual Canadian Superbike champion on a Suzuki) was disqualified from an AMA race at Loudon after it was decided the device gave him an unfair advantage over the competition. | ||
| Blake |
Interesting. Clarification: Swept area as I understand it (area engaged by brake pads and subject to heating) would be unaffected, but the sweeping speed would certainly increase. The anti-dive would seem unrelated as it would necessarily involve some kind of interaction between fork upper (sprung) and lower (unsprung) sections and the brake would seem to need to be entirely on the sprung side of that equation. but maybe not. I'm very intrigued by the whole gyro effect topic as it relates to motorcycles. I'm tempted to goof off and come up with a spreadsheet to describe the magnitude and effect of gyroscopic wheel forces for various motorcycling scenarios. Tony Foale already did that for the motorcycle as a whole. | ||
| T9r |
Drawing from pattent. http://thekneeslider.com/archives/2006/02/17/reverse-rotating-brake-rotors/ | ||
| Lornce |
I suppose the *effective* swept area is increased if the rotors are moving faster than the wheels. ie: the pads see more disc area/wheel rev than conventional brake set-ups. Does that make sense? I can't remember the anti-dive angle, it was a long time ago, but there may have been some sort of lever attaching the caliper to the lower triple clamp. Or maybe I'm thinking of another system from that era? Also, Paul MacMillan was his number one rider, not Jeff. Though he also raced for Kieth, Jeff wasn't as successful as his brother Paul. (Message edited by lornce on February 22, 2006) | ||
| Blake |
I'm with you. It's less an increased effective area, more an increased effective inertia. Outside the intended anti-gyro effect, I don't see a major benefit to it, same area means same amount of heat generated, all else being equal. The applied braking force would be reduced though. That might be beneficial. Interesting stuff.  Would be interesting to do the free body diagram for the forks and compare it to a conventional arrangement. | ||
| Lornce |
Would the swept area not be greater if the rotor was turning at a speed, say 1.5 or 2 times the wheel speed? The area of the rotor's surface is the same, but the pads are *sweeping* more of it than if the rotor was turning the same speed as the wheel. Does that not equate to the same thing as increased "swept area"? ie: it's effectively seeing a longer rotor than a conventional set-up. No? | ||
| Blake |
Not to my mind on account of a truly larger rotor would offer increased heating capacity. On a conventionally mounted or even ZTL disk brake, does the swept area increase with increasing speed? What is the benefit of a faster spinning brake rotor if it still must endure the same amount of heating? | ||
| Djkaplan |
It would also heat up quicker and not be able to conduct the heat away as fast. You can't have something for nothing. | ||
| Lorazepam |
what about drag in the gearing? you are gaining weight, and adding resistance with the gearing to make the rotor spin, no? | ||
| Lornce |
"What is the benefit of a faster spinning brake rotor if it still must endure the same amount of heating?" I suppose I'm thinking in terms of frictional coefficients. If the pads bear on 1.5 times the frictional surface area for any given speed does that not equate to greater stopping power? I'm assuming there's a set amount of energy/swept area for any given clamping force. Increase the swept area and the breaking energy increases also? I'm just thinking out loud here.... | ||
| Blake |
Yes, it would act like a lower gear as seen from the brake lever, so all else being equal, lever effort would be reduced proportionally, just like you say. That's shat I meant above when mentioning that "the applied braking force would be reduced...", which in rereading was very poorly worded. Blake no write good. I'm not clear if that is something desirable or not. The current crop of sport bike brakes seem to work okay in that respect. |
