Abstract: A brake system for a drawworks includes a hydraulically actuated band brake system having a backup spring actuator for emergency stops. The system also includes a caliper disc brake system for emergency stops. The disc brake system includes a rotor directly mounted to the drum barrel and a pair of spring actuated caliper assemblies.

Abstract: A well drilling apparatus includes a monitoring system for monitoring the exact elevation of the traveling block. The monitoring system detects the elevation of the traveling block by means of periodically transmitted signals which are reflected back to the monitoring system by the traveling block. The apparatus further includes a control system preferably including an industrial control digital computer which is responsive to the elevation of the traveling block and controls the drawworks of the apparatus to prevent the traveling block from crashing into the crown block or working floor. In one embodiment of the apparatus the velocity of travel of the traveling block and the load being supported by the traveling block are also monitored in order to further restrict raising and lowering of the traveling block to be maintained within predetermined safe limits of operation.