Quote:
Originally Posted by Piotrsko
12 speed? Thats a 4 speed with a 3 ratio brownie behind it. Not all that efficient unless you spend a bunch of time figuring out gearing so that the shift drop puts you into the beginning of the torque curve of that particular engine. Gonna need at least three engine specific transmissions in America.
In Poland, rode a russian made bus that had an 8 forward geared auto. Up to their freeway speeds, all it did was hunt the gears until the bus went steady state on that freeway. 1200rpm climb to 1600, shift, repeat at least 5 more times in the first mile, you're now at 35-40 mph, hard to read the speedo from the first right side seat. 1200 is a bit high for max torque, 1600 is a bit low for max hp. Driver tromps the go pedal, downshifts twice, but not that often because like all pro drivers, the go.pedal has 2conditions: full on, full off. Nicest thing about that russian trans was it didn't shift when you got off the throttle, either up or down.
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That's the whole point of the 12-speed.
It's close-ratios, with minimum BSFC 'island-hopping' between gears, allows the engine to remain in it's optimum rpm range of efficiency.
The engines are at, or exceed 1,800-pound-feet of torque, exceeding the capabilities of CVTs when Ricardo did the reporting, hence, the 'conventional' transmission.
Telsa's Semi does an end-run around the issue. It's BSFC-e of 0.135 lbs/ bhp-hr-e, gasoline-e , and 95% BTE-e 'slays' ALL the 'Diesels', hands down. A 'two-fer.'
Also, for dedicated clients, like Frito Lay, where their semi-trailers are only hauling lightweight potato chip-like products, they could operate with dedicated, ' light-weighted' semi-trailers of 'half' the mass, with 'all' the strength necessary, allowing even greater pack capacity, and range, with no weight penalty. ( there's no reason to operate a 'trailer' engineered to carry 'bowling balls', when carrying ' cotton balls'). Adam Smith would 'pity the fool'!