Would 1 gear be better for a electric motor?

Since a electric motor torque is instant wouldn't it be better for acceleration to have one gear with a lower gear ratio? Or can an electric car benefit from like a 5 speed transmission for acceleration?

5 Answers

  • 6 years ago
    Favorite Answer

    You are asking about what would be better for an "electric motor" when I think you want to be asking about a specific application. In this case, you seem to be asking about the best way to match an electric motor to an electric car.

    "Best" is always dependent upon the desired results. If you were asking about cost in a conversion vehicle the transmission is often left in place because the adaptation is less time consuming and less costly.

    In a commercial electric car, that is not also a hybrid with other requirements, vehicles almost universally have a fixed gear ratio and no transmission with adjustable gear ratios.

    Acceleration is dependent upon several factors.

    - Torque is a primary component. An electric motor has enough torque to not require the shifting transmission that is essential for acceleration in an internal combustion vehicle.

    - But also significant is the time required to shift from one gear to another. By eliminating the loss of power and time required for shifting the electric car gains another advantage for acceleration.

    - Transmissions can also be heavy. The electric motor is far lighter than an internal combustion engine and a simple fixed gear ration is far lighter than a 5 speed transmission. This savings in weight is also a benefit to acceleration and overall we sometimes refer to the power to weight ratio of the engine or vehicle.

    There are just a few exceptions. Many years ago controlling motor speeds was more problematic. In the past either DC motors were used or AC motors with a transmission, but this had more to do with economics and efficiency than acceleration.

  • Eric P
    Lv 6
    6 years ago

    It depends on the motor that is used. Some motors have plenty of speed range and power output to operate a vehicle through a fixed gear ratio. The Nissan Leaf and Tesla models operate this way.

    In some electric car retrofits, smaller or less expensive motors are used that may not have enough output or speed range to power the vehicle through a fixed ratio. In this case, an automotive manual transmission can be attached to the motor output to enable torque multiplication at low speeds and higher ratios for higher-speed travel without over-spinning the motor.

    There's no reason to use a different motor for reverse. Electric motors spin just as well in either direction. You can program the controller to limit the speed in reverse.

  • ivan k
    Lv 5
    6 years ago

    If you design the motor right it won't have any use for any more than 1 gear for all speeds between zero and 100.

    For motors commercially available to back yard EV builders, transmissions are helpful for low speed efficiency.

    They are not needed for acceleration because the motor direct driving the axle can easily max out the tire's traction off the line.

    A transmission would just be for efficiency at low speed. Maybe for towing. I suppose you could also use a less expensive controller if you use a transmission for reverse.

  • Rocky
    Lv 6
    6 years ago

    electric motors use a resistor that according to how fast you want the revelations per minute allows electric to flow into the motor - the more volts/amps the faster and more revolutions per minute it goes - sometimes a bleed down resistors are used there are different types for different uses.

    Most motors will allow you to use a knob like power controller so that you can start it with like 5 volt/amps (according to the motor) and rev it up to max revolutions/speed

    No need for transition except for reverse if the motor is not a variable motion then you'd disengage the forward movement motor and actually it probably would be safer to have a smaller motor that is limited by its size and therefore revolutions to be reverse - what with so many people backing up into stores and buildings because it got away from them in reverse say one 1/4 as large

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  • 6 years ago

    NO, because some drills like a 90 degree drill needs more gears for different angles. Mike

    Source(s): Logical
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