A radial piston machine includes a housing, rotor, first braking member, and brake ring with a second braking member. The rotor is mounted in the housing to be rotatable relative to an axis of rotation, and has an end face facing in a direction of the axis of rotation. The first braking member is positioned on the end face. The housing has a body defining a ring-shaped extension relative to the axis of rotation. The brake ring is positioned to surround the extension and is configured to be movable in the direction of the axis of rotation so as to bring the second braking member into braking engagement with the first braking member. The brake ring is further configured to positively engage with an inner radial side of the extension to limit a twisting between the housing and brake ring.

A hybrid drive system for a motor vehicle, and a method for operating a motor vehicle. The hybrid drive system includes an amplidyne-type generator and a counterpoise engine to provide the power required for charging the storage batteries and providing supplemental drive energy (acceleration) to the motor vehicle.

A radial piston machine includes a housing, rotor, first braking member, and brake ring with a second braking member. The rotor is mounted in the housing to be rotatable relative to an axis of rotation, and has an end face facing in a direction of the axis of rotation. The first braking member is positioned on the end face. The housing has a body defining a ring-shaped extension relative to the axis of rotation. The brake ring is positioned to surround the extension and is configured to be movable in the direction of the axis of rotation so as to bring the second braking member into braking engagement with the first braking member. The brake ring is further configured to positively engage with an inner radial side of the extension to limit a twisting between the housing and brake ring.