A crane has a hoist rope which passes over a boom to a drum driven by a hudraulic motor and including a brake. The crane includes means for releasing the brake when the free end of the rope is a given distance below the crane, and has means for relieving hydraulic pressure from the motor in response to the horizontal radius of the free end of the rope so that at a given radius the motor can lift only a given maximum load.
A snag load protection system for a train including a guide frame, a sheave housing slidably received within the guide frame, and a hydraulic cylinder connected to the guide frame and to the sheave housing. The hydraulic cylinder serves to exert a compressive force against the sheave housing so as to resist relative movement between the guide frame and the sheave housing when forces exerted by the sheave housing are within a predetermined value. A relief valve is connected to the hydraulic cylinder for releasing hydraulic fluid from the hydraulic cylinder when the force is greater than the predetermined value. Pressure and position limit switches are connected to a motor so as to stop the movement of a hoist rope when forces exceed the predetermined value.
