An early type of hydrodynamic drive consisting of an impeller driven by the engine and a turbine connected to the transmission, both enclosed in a fluid-filled casing. It transmits rotational power through the kinetic energy of transmission fluid rather than a mechanical friction clutch. Unlike a true torque converter, it does not multiply torque.
Heard on the job
The old preselector gearbox relies on a fluid flywheel to allow the car to idle in gear without stalling.
Do not mix it up with
- Torque converter: A torque converter has a stator to multiply torque, while a simple fluid flywheel only transfers it at a 1:1 ratio.
Related terms
Torque converter
A fluid coupling that transfers rotating power from the engine to an automatic transmission.
Transmission
The mechanical or hydraulic assembly that adapts engine power to drive the wheels.
Automatic transmission
A gearbox that changes gear ratios independently without a manual clutch pedal.