Eli5: how can you roll start a manual vehicle but not an automatic vehicle?
In: Other
An automobile clutch, clutch being the general term we use for a device that can allow and disallow twisting, is a powerful spring that pushes a friction plates against each other that allow the engine and the transmission to connect to each other while retaining the ability to disconnect them by using a strong lever – like a clutch pedal.
In typical driving the engine is generating power by harnessing enough combustion energy to both push the piston back down, push a corresponding piston up, AND provide enough torque to twist something connected to wheels – in a car that would be a transmission since a car can only develop enough torque to effectively power a vehicle in a narrow band of RPM.
If the car is moving but the engine isn’t, the condition you find yourself in when you depress the clutch and release the brake and are either going down a hill or being pushed, if you release the clutch you send the kinetic energy from the drivetrain into the engine – the opposite of normal driving. If you do this with the ignition on (so the battery is OK-ish) you mimic the behavior of a starter motor. The engine spins until you get a successful inhale/compression/sparl-combustion/exhaust.
Latest Answers