Abstract: A brake for a railway vehicle has a transmission whose input is connected to a drive motor and whose rotary output is connected through a free-running stepdown transmission to an eccentric that rotates about an axis perpendicular to the direction of displacement of a follower operatively radially engaged with this eccentric. A pack of springs is braced between an abutment spaced to fix distance from the rotation axis of the eccentric and the follower so that this eccentric can load these springs. One arm of a caliper is connected to the follower and the other end thereof carries a brake pad engageable with a brake disk carried on a wheel. The springs are at maximum compression when the brake is off and vice versa so that if power fails the springs will automatically close the caliper on the brake disk and stop the vehicle.