1. The engine cranks a pump that turns both the drive shaft and a tilted metal disk [A].
2. As the disk spins, it depresses a circular set of pistons [B] around the shaft.
3. The pistons eject high-pressure fluid that travels through a chamber [C] and pushes out a second set of pistons [D].
4. Those pistons press a second tilted disk [E], causing it to spin and transmit extra torque (leverage) to the drive shaft.