Dog Gear Transmission

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Originally Posted By: bullwinkle
I'm a little confused-doesn't a manual transmission clutch operate with ZERO slippage once applied, for NO power loss? I missed something somewhere!


This is helping to ensure that there is as close to zero loss to friction as possible. And, the clutch is a pretty big, heavy thing to have to spin. Much less a dual-clutch transmission that is spinning two clutches at the same time. That uses a fair bit of energy that could go to driving the wheels. Plus all the complicated mechanisms to automatically operate each clutch. This design replaces all those parts with a much simpler, less energy-sapping setup.

If the car is already a hybrid with a giant electric motor and battery, that's already a sunk cost for weight. Adding simplicity and lightness in other places is still a worthwhile goal.
 
If I understand: they add an electric motor to the (output?) of the transmission. Its purpose is to get the car moving. When up to speed the engine is started and spun to the right speed, and then is mated to the transmission. The "gain" is loss of weight from removing the heavy clutch, and perhaps 1st&reverse components.

Not a bad idea, although the battery pack has to be hefty enough, and a "large" electric motor has to be added. Still, as one more method of coupling engine to road it makes sense to me: a hybrid method for city-esqe driving, but direct coupled ICE for the upper speeds. Prius does quite well on its hybrid approach but this sort of approach would be more optimized for the open road (no need to circulate power between mechanical to electrical to mechanical). I believe VW had a similar idea, albeit with a single gear ratio.
 
Originally Posted By: bullwinkle
I'm a little confused-doesn't a manual transmission clutch operate with ZERO slippage once applied, for NO power loss? I missed something somewhere!
Nope There is slippage by design for gear shifts. "Grab" is near perfect but due to the way a clutch functions, frictional losses are unavoidable. A locking torque converter is more positive.
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Given the un-needed complexity, and the sizing of the big motor to the limits of traction, the Prius system is much more simple and effective.
 
Remove the clutch, but then they may have to add weight to the flywheel to compensate for the lost mass. 5 to 7 lb in lubricant - so it uses no oil as well ?
 
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