Abstract: The invention provides an overspeed protection system for a vehicle such as a mine skip travelling along a vertical set of rails 60. In use an idler wheel 62 in contact with a rail 60 rotates a shaft 12 forming part of a clutch 10 at speeds which are directly proportional to the linear travelling speed of the vehicle. When the rotational speed of the shaft 12 exceeds a predetermined limit the clutch 10 frictionally transfers torque from the shaft 12 to a shaft 14, which in turn drives an hydraulic pump 64. The pump 64 pressurises hydraulic fluid in a supply line 67 until it opens a valve 68, which admits a pressurised fluid from a reservoir 74 into a braking means 80, which performs a clamping action on an associated rail 60 to restrain the motion of the vehicle.