Guru
Joined: 09/08/2007
Location: AustraliaPosts: 4406
| Posted: 11:25am 27 Nov 2012 |
Hahaha Pete, the manual transmission guys used to call all automatics "slush boxes".
They were originally all controlled by hydraulics within the transmission itself.
To get it to change gear more firmly, or at a different rpm, you had to start changing springs, re drilling passages and all that was a real specialist job for the experts.
You could buy manual shift kits, and various custom bits and pieces, and some of the drag racers even ditched the torque converter altogether and fitted a manual clutch to the automatic transmission. Google "clutch flite" which was a very popular clutch conversion of the Torqueflite auto back in it's day.
The years roll by, and technology constantly changes, and the fully electronic automatic transmissions of today are very different to the all hydraulic originals of only a few years ago. All the internal functions are controlled electronically, except for the mechanical parking brake when in "park".
An electric vehicle works fine cruising down the road at constant speed, but without a gearbox the acceleration from a standing start can be quite poor. A gearbox offers extra torque when climbing steep hills or when very heavily loaded. It just improves both performance and efficiency. They even fit multispeed gears to bicycles for the same reasons.
You will get much better motor acceleration efficiency by letting it rev under light load in a low gear, than pouring amps into an almost stalled motor in a very high gear. Once up to speed, you slip into a tall gear.
Pete, probably the strongest automatic transmission around is the two speed Allison, they are HUGE, and commonly fitted to buses and those large garbage dumpster compactor trucks. They are also a favorite transmission used by guys building land speed record vehicles powered by Rolls Royce Merlin and Allison Aero engines. No other automatic transmission can handle the 2,000 to 3,000 Hp that some of these vehicles have.
An electronic automatic transmission/differential from a small front wheel drive car, direct coupled to a high speed dc electric motor would make an excellent electric vehicle. Very easy to control, simple, robust and reliable.
You can even buy suitable aftermarket programmable electronic transmission controllers that plug into your lap top computer.
With that, you can very quickly change the gear shifting points versus road, motor speed, and throttle position, to get the transmission to behave exactly any way you wish. With a bit of data logging and experimentation it should be possible to get the transmission to change gear in a way that gives best overall energy efficiency under a wide range of conditions. An adaptive self learning program should also be possible.
Cheers, Tony.