Abstract: An electro-hydraulic automatic seat brake system which is effective to automatically set the hydraulic service brakes and shut down the engine of an industrial vehicle whenever the operator's seat is unoccupied. In order to release the brakes after the seat is reoccupied, the operator must turn on the engine ignition circuit and close a separate brake release switch. The system is charged immediately upon starting the engine by means of an engine-driven pump before other hydraulic components can be operated, and the charge is maintained when the engine is shut down by means of an accumulator. According to one aspect of the invention the hydraulic pressure on the service brakes is automatically released when a mechanical handbrake is set. According to another aspect of the invention means are provided to allow the engine to keep running when the operator's seat is unoccupied, provided that the vehicle transmission is in a neutral condition.

Abstract: Hydraulic systems particularly adaptable for use in industrial lift trucks utilizing two or more hydraulic cylinders to lift a load. The cylinders are positively connected to the load, and valve means are provided for directing pressurized fluid to the working chambers of all cylinders when heavily loaded and to fewer cylinders when lightly loaded. Other valve means are provided for directing fluid to the working chambers of the unpressurized cylinders.