Longwall mining machine with haulage motor sensed pressure controlled rail brake

A mineral mining machine comprising haulage mechanism including a hydraulic motor for hauling the machine to and fro along a rail extending along a longwall face, first hydraulic pump means for feeding pressure fluid to drive the hydraulic motor, a first hydraulic control for controlling the feed of pressure fluid to said hydraulic motor, a resiliently biased rail-engaging brake operable under its resilient bias towards its applied position to prevent movement of the machine along said path, second hudraulic pump means separate from the said first hydraulic pump means for supplying pressure fluid tending to move the brake against its resilient bias towards its released position to allow movement of the machine along said path, a second hydraulic control for controlling the supply of pressure fluid from said second hydraulic pump means to said brake, and means responsive to the operational condition of the machine's haulage mechanism to thereby actuate said second hydraulic control to block off the pressure fluid supply to cause application of said brake against said rail to prevent uncontrolled movement of the machine along said path.