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Old 09-27-2014, 10:22 AM   #21 (permalink)
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Originally Posted by freebeard View Post
Hydraulic clutch? If you remove the engine and transmission, what does the clutch attach to?
You don't remove the transmission. You make an adapter plate to mount the electric motor to the transmission, and the flywheel to the output shaft of the motor. DC motors have a relatively narrow efficient operating RPM, so we keep the transmission and use maybe three gears to get the best acceleration in every situation.
mechman600 -- Is there a second reason for retaining the clutch? Because I watched a Youtube video of a Porsche EV conversion, and as he was driving he'd say, "Oops, there goes the clutch...there goes the clutch."

Won't a switch like they put on the outside of race cars substitute?
Not sure why he said that. He likely was using the old original clutch which couldn't handle the increased torque of a ginormous DC motor.

You always need redundant safeties build in, like a contactor or two. Rule of thumb: engineer it so that if ANY two devices fail, you will be able to stop the car.
For example, a failed closed controller & failed closed contactor - without a clutch you are screwed, flying down the road in a runaway condition, which is why it is recommended to use TWO contactors in a clutchless DC powered EV.

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