Abstract: A brake system for braking a shaft of an apparatus subject to runaway to stop runaway. The system comprises a brake drum on the shaft, one or more brake shoe(s) engageable with and disengageable from the drum, and a control member connected to the brake shoe(s) movable in one direction to a first position for applying the brake shoe(s) and in the opposite direction to a second position for releasing the brake shoe(s). The control member is biased to its first position for applying the brake shoe(s), and a torque motor is connected to the control member for moving the control member on energization of the torque motor to the second position and holding it there for release of the brake shoe(s). A device responsive to runaway of the apparatus for de-energizing the torque motor is provided, the control member being released on de-energization of the torque motor for applying the brake shoe(s) to the drum.