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An extra gear would not give more performance, the reason cars with internal combustion engines have gears is because they do not produce their full power at lo

by tyho 12y ago

An extra gear would not give more performance, the reason cars with internal combustion engines have gears is because they do not produce their full power at low engine speeds, whereas electric motors do, hence why the Tesla does not have nor would benefit from a gearbox. You can see why a gearbox is a disadvantage in this video here: http://youtu.be/0e-jquwHKtI?t=30s http://youtu.be/0e-jquwHKtI?t=30s During the first 2 gear changes you can see the lambo fall behind during gear changes.

semi-extrinsic 12y ago
s/power/torque/ And saying a Tesla would have no benefit of a gearbox is a bit strong. There are reasons to believe [1] it would increase efficiency at the cost of more complexity. [1] http://www.gizmag.com/new-multi-speed-electric-vehicle-transmission-improves-ev-performance-and-range/11670/ http://www.gizmag.com/new-multi-speed-electric-vehicle-trans...
- tyho 12y ago
  I was speaking a bit imprecisely. An electric motors power-speed curve is not totally flat, just much more so than normal engines.
Animats 12y ago
Tesla's original cars had a 2-speed gearbox, because they had problems with the motor at high revs and they couldn't get their desired top speed without a gear change. The gearbox was a huge problem, because the shift ratio was so big that the jolt on gear change damaged the gearbox, and gearbox life was maybe a year. So they went to a motor with a larger speed range and better cooling, and a one-speed gearbox. Tesla retrofit most of their early cars with the new powertrain. http://www.teslamotors.com/blog/engineering-update-powertrain-15 http://www.teslamotors.com/blog/engineering-update-powertrai... Some earlier electric cars had multi-speed gearboxes, but that was back when electric cars had brush-type DC motors. Once high-power semiconductors got really good, electric cars went to polyphase AC motors with variable-frequency drive. That technology is now in everything from better R/C drones to electric locomotives. AC motors can be made to synchronize, which allows the Tesla 2-motor car to have all-wheel drive with no front/back differential. One motor per wheel is probably next. The big win for this technology turns out to be Diesel-electric locomotives. All the wheels on all the locomotives can be synched up, eliminating wheel slip. The locomotives can even be distributed through the train. Here's a 3.5 mile long train run as a test by Union Pacific in 2010. https://www.youtube.com/watch?v=jdIzRFOaTCY https://www.youtube.com/watch?v=jdIzRFOaTCY There have been longer trains, but mostly in flat areas. This was from LA to Texas at speeds to 70mph.

by tyho 12y ago

semi-extrinsic 12y ago

s/power/torque/ And saying a Tesla would have no benefit of a gearbox is a bit strong. There are reasons to believe [1] it would increase efficiency at the cost of more complexity. [1] http://www.gizmag.com/new-multi-speed-electric-vehicle-transmission-improves-ev-performance-and-range/11670/ http://www.gizmag.com/new-multi-speed-electric-vehicle-trans...

tyho 12y ago
I was speaking a bit imprecisely. An electric motors power-speed curve is not totally flat, just much more so than normal engines.

Animats 12y ago

Tesla's original cars had a 2-speed gearbox, because they had problems with the motor at high revs and they couldn't get their desired top speed without a gear change. The gearbox was a huge problem, because the shift ratio was so big that the jolt on gear change damaged the gearbox, and gearbox life was maybe a year. So they went to a motor with a larger speed range and better cooling, and a one-speed gearbox. Tesla retrofit most of their early cars with the new powertrain. http://www.teslamotors.com/blog/engineering-update-powertrain-15 http://www.teslamotors.com/blog/engineering-update-powertrai... Some earlier electric cars had multi-speed gearboxes, but that was back when electric cars had brush-type DC motors. Once high-power semiconductors got really good, electric cars went to polyphase AC motors with variable-frequency drive. That technology is now in everything from better R/C drones to electric locomotives. AC motors can be made to synchronize, which allows the Tesla 2-motor car to have all-wheel drive with no front/back differential. One motor per wheel is probably next. The big win for this technology turns out to be Diesel-electric locomotives. All the wheels on all the locomotives can be synched up, eliminating wheel slip. The locomotives can even be distributed through the train. Here's a 3.5 mile long train run as a test by Union Pacific in 2010. https://www.youtube.com/watch?v=jdIzRFOaTCY https://www.youtube.com/watch?v=jdIzRFOaTCY There have been longer trains, but mostly in flat areas. This was from LA to Texas at speeds to 70mph.