Abstract: Apparatus for rapidly braking the rotary blade of a rotary mower driven by an internal combustion engine. The internal combustion engine has a plurality of passages which lead to its combustion chamber for provision of a fuel-air mixture for combustion in the chamber and for exit of exhaust gases from the chamber. The apparatus includes a valve located in one of these passages which effectively blocks the passage when manually operated means for actuating the valve are operated. In one embodiment, a release of a dead man handle used in conjunction with the mower causes actuation of the valve by means of a bowden wire linkage connected between the dead man handle and the braking valve. The apparatus may also include a switch operated simultaneously with the braking valve to provide an ignition spark arresting function.