Abstract: A manually initiated, brake actuating system for immediate stoppage of the traveling block in a drilling derrick drawworks that overrides a conventional automatic drawwork safety control device. The system includes a normally closed, solenoid-controlled pneumatic valve mounted in an explosive resistant container between the system air supply and the pneumatic brake for the drawworks drum. A manually operated electrical switch, when actuated, simultaneously (1) energizes the solenoid to the emergency override pneumatic valve,and (2) de-energizes the drawworks power circuit, cutting off power to the drawworks motor.