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Gears in electric car
(11 posts, started )
Gears in electric car

How do gears work in an electric car?
As electric cars produce maximal torque across whole rev spectrum, the gearbox for keeping revs in optimal range is not necessary. Therefore they usually only have one fixed gear for any speed (although some experimental/racing crafts can have high/low gear four whatever reason).
also if you want the ratio of a given pair of spur gears is calculated by dividing the number of teeth on the driven gear, by the number of teeth on the drive gear
Electric cars can still benefit from gearing, but far less so than combustion engines. Low speed acceleration is generally already more than competitive. Keeping power at higher speeds is not really a concern for your typical road car, given that manufacturers are now looking to bring top speeds down. As such, the extra cost and complexity is not needed.

No gearbox also makes packaging the a motors into the each wheel much more practical and then you don't need a differential either and can just rely on electronic torque vectoring for managing stability and variant wheel speeds. It's a more modern but ultimately much more flexible solution.
^^ informative and true. never had a chance to say hi before, so hi bob great to meet you
#7 - ZanZi
Two of the main limiting factors as of now for geared electrical motors are the torque output and high rpm. The higher the torque output, the stronger the gears/shafts/bearings need to be which in terms adds roational mass that can not spin at infinite rpm.
The general concept of dc (brushless) electrical engines have current output limit that in term limits the 0 to low rpm torque output. As rpm's rise, torque increases as to a point that voltage becomes the bottleneck. Top end rpm is achieved by dropping the current, as so torque drops dramatically.
Ive been toying with the idea of a CVT gearbox, purely for simplicity sake, engine torque can be limited at all times so it will not cause slip in the belt driven conical gears of a CVT, top end rpm can be given a little boost in torque as CVT can provide a more suiting gearing ratio... its all just theory.

Rimac use a nice and well packed design on two gears (low and tall) gearbox, that seems to be working well for them and their customers.
I have been thinking about this subject and one good solution is the planetary gear system. This type of gearing is very flexible and it has many options. You can either choose to make a planetary gear system which increases the output RPM (at the same time, decreses the output torque by the same ration) or decreases.

planetary gears

According to this picture, if the sun-gear is spinning at 3000rpm (the standard top spped for an AC motor), the planet-gears will be spinning at 7000rpm (more or less the max rpm for a standard road car). The output torque will be lessened by the same ratio of imput and output speeds.
You can benefit from gearing in electrics. Way less than in normal engines though.
#10 - 5tag
Quote from Marino108 :According to this picture, if the sun-gear is spinning at 3000rpm, the planet-gears will be spinning at 7000rpm.

That doesn't make sense. One of the three (ring, planet carrier, sun) has to be held in place, otherwise you can't transmit any torque.
Quote from racer1012 :You can benefit from gearing in electrics. Way less than in normal engines though.

Having gears on electric cars would be of no benefit, they just do not need them to run efficiently,and it would only add weight which would then have a negative effect for no improvement in the running of said engines

Gears in electric car
(11 posts, started )