This invention relates to an operable skate type of railway car retarder including a plurality of inner and outer levers pivotally supported on the cross ties and physically disposed on opposite sides of a track rail. Each of the inner and outer pivotal levers supports an elongated braking element which is disposed parallel to the track rails. Each of the outer pivotal levers of the car retarder is operated by an actuating mechanism. Each actuating mechanism includes a power operating unit as well as a locking unit. The power operating unit utilizes a fluid piston and cylinder as well as slide piston and guide cylinder to raise the outer lever to cause the braking element to assume a braking position. The locking unit includes a fluid piston and cylinder operating a lock block which engages the slide piston and locks the lever in its braking position or disengages the slide position and releases the lever allowing the retarder to assume its nonbraking position.