Abstract: This invention relates to an overload protection apparatus for hydraulic multi-function equipment. It is applicable to equipment sharing a common pressure and return line and in which functional operation of the equipment is interrelated such as to expose certain elements to overpressure conditions. The system includes an overload or overstress valve having a manifold to which the power lines of all of the actuators, except the principal actuator which responds to an overstress condition, are connected. These connections are directed through check valves so that fluid within the lines will be directed only to the overstress valve. A pilot valve connected to the power side of the principal cylinder controls a pressure actuated control valve in the manifold to control and open a passage to the reservoir.

Abstract: A multiple servo system including two or more servo mechanisms, each having a pressure feed back including two pistons exposed in respective chambers interconnected by a low-pass hydraulic filter, in which the area of the two feedback piston faces differ by up to 25%. This reduces the tendency of the respective actuators to act in opposition and thus increases the service life of the system.

Abstract: The self-actuating fluid holding system includes a fluid pump and two fluid valves and two fluid motors all fluid-flow connected together. The valves are arranged to sense the proportionate flow therethrough and to the two motors, and when the flow is out of proportion, such as when one of the connecting lines or a connection breaks to permit the fluid to leak, then the valves have shut off closures which protect the system against fluid leakage.

Abstract: A load responsive fluid power multiple load control system using load responsive direction and flow control valves in combination with pump control responding to highest system load. Each direction flow control valve is equipped with a single load responsive controller which automatically regulates fluid flow into and out of the fluid motor to maintain a constant pressure in front of a variable flow controlling orifice, during the control of both positive and negative loads. The load responsive controller of each direction control valve blocks the pump flow to the motor while controlling negative load, providing the motor inlet with fluid from the motor exhaust.

Abstract: Each consumer is provided with a load-compensated direction-reversing valve. Each valve performs a throttling function and a pressure-compensation function in order to establish a selected volumetric flow rate, and also a direction-control function. Each valve comprises a first control valve stage and a second control valve stage. One stage performs the throttling function, the other the pressure-compensation function. One of the two control valve stages also performs the direction-control function. The pressure drop across the stage which performs the throttling function at least in part controls the setting of the stage which performs the pressure-compensation function. Each valve is provided with an electromechanical transducer generating electrical signals indicative of the settings of the stage which performs the pressure-compensation function.

Abstract: A device for distributing pressurized fluid to first and second movable consumers while maintaining a fixed ration between the fluid flows to the consumers, including rotary flow value gauges for directing a return flow from each consumer to an associated gauge, a comparator interconnecting the gauges without one gauge being dependent on the other gauge as to the rotation of the gauges and sensing differences between the output flow of the gauges, inlet valves activated by the comparator to regulate the flow to each consumer for maintaining the fixed flow ratio, and throttle valves for the return flow from each consumer and activated by the comparator to throttle the return flow from a consumer to slow down such consumer.