Hoistman had shut off the air to the clutch actuator piston to make adj. Miners rang for the cage, hoistman forgot to reopen the valve, which left the clutch disengaged. Hoistman lowered the cage, it started to free fall. He then slammed on the brake causing the cage to stop suddenly. Injuring 1 of the miners. The miner that was injured has a lumbar disc herniation.