Drawworks Brake Testing Checklist

The drawworks brake is the last mechanical control between the drill string and uncontrolled fall. If the brake slips, the block drops, the elevators fail and the pipe is lost. The testing sequence therefore starts before the brake is ever loaded with pipe. The cold check establishes the baseline: brake band gap, lining thickness, drum runout, hydraulic accumulator pressure, and the response of the dead-man pedal. Any of those numbers out of spec should stop the job before the first connection is broken. The first test is the static hold. With the block off bottom and the brake applied, the drawworks should hold the suspended load without creep for the time the operator program requires. A load that inches downward indicates a slipping brake band, a weak accumulator, or an air-system leak. The next test is the controlled lower. The driller should lower the block at a controlled speed, stop it, and reverse direction without jerking the drill string. A jerky stop or a delayed response points to hydraulic lag or air in the system. The emergency stop test is the one that proves the system. The driller should bring the block to mid-height, apply the brake, and cut the drive power. The block should stop within the distance the driller can see from the remote panel. A long stop distance means the brake is not capturing the drum fast enough, or the band is worn past the discard limit. That distance should be measured, recorded and compared to the last test. An increase in stop distance is an early warning that the brake needs service. The final check is documentation. The brake test record should include drum temperature, accumulator pressure, lining thickness, test load, stop distance and the inspector name. Those records should travel with the rig and be available to the operator before the next spud. A drawworks brake test that is not recorded is a test that cannot defend the crew if the brake fails later. The same accountability rule applies to other mechanical checks in rig equipment inspection checklist. ← Back to rigs.work