Abstract: A hydraulic-pressure counter-force mechanism 37 which produces a counter force when a brake booster is operated is made up of an input-side member 38 slidable disposed within a valve body 3, a second constant-pressure chamber 39 formed on the rear side of the input-side member and into which a pressure is introduced from a constant pressure chamber A, and a second constant-pressure chamber 39 formed on the front side of the input-side member and into which a pressure is introduced from a variable pressure chamber B. The counter force from the hydraulic-pressure counter-force mechanism 37 is reduced by an orifice passage 43 as counter-force reducing means in rapid operation for brake.

Abstract: An electrohydraulic control system for a hydraulic working cylinder, for example of a press, the piston of which has a main working surface and a smaller working surface on the rod side. A low-pressure circuit is provided for the feed or retraction movement of the piston, and a high-pressure circuit is provided for the loading movement at increased feed force and reduced speed. The connection or disconnection of these two circuits, when required, is produced with two 3/2 way valves that are coupled together. To control these control valves, there is provided an electrical reference motor that drives a cam disk which brings about the deflection of the coupled control slide valves of the control valves against a spring. A mechanical feedback is provided via the power piston, so that altogether a closed hydromechanical position control circuit is formed.

Abstract: A wheeled vehicle is equipped with a feedforward steering control system which steers the vehicle through front or rear road wheels in accordance with a driver's steering input such as an angular displacement of a steering wheel, and a negative feedback system which senses a turning behavior of the vehicle such as a yaw rate or a lateral acceleration, and steers the vehicle through the front or rear wheels in such a negative direction as to reduce the turning behavior. The feedforward system may control the angular direction of the front or rear wheels in accordance with a linear combination of the steering input and the time derivative of the steering input, or may control the angular directions of both of the front and rear wheels in accordance with different transfer functions between the steering input and the front and rear wheel angles. The negative feedback system is combined with the feedforward system in various ways to provide desired characteristics of the turning behavior.

Abstract: A servo amplification system is created particularly for heavy construction equipment, but has a general utility that is much broader. The system utilizes a hydraulic analog system with a separate subsystem for each dimension of motion. The operator moves the operative element, such as the backhoe bucket, of the analog replica which ordinarily would be situated in the cab of the backhoe or other piece of equipment. A small hydraulic cylinder operative in response to movement at each articulated connection of the backhoe operates a pilot valve which controls a pilot piston mechanically linked to the drive valve of the drive cylinder of the corresponding articulation in the actual backhoe. A feedback system comprising a mechanical link from the actual drive piston to a feedback cylinder and piston delivers hydraulic fluid back to the inlets of the pilot valve in such a way as to cancel the pilot orders from the initial control cylinder.

Abstract: A simplified construction of a comparator is provided in an automatic steering system utilizing dual chambers separated by a membrane, e.g., a diaphragm or bellows. Each side of the membrane operates a respective valve which valves are normally open but can control flow to a hydraulic cylinder for steering or centering the wheel of an agricultural vehicle. Fluid flows through the chambers which connect to exhaust through variable throttle valves. Sensors, i.e., feelers, follow rows of plants and when the feelers are deflected they operate respective throttle valves which cause a buildup of pressure in a respective chamber. Such differential pressure between the chambers flexes the membrane in a direction to operate the valves within the chambers. Operation of such valves effects directional pressurizing of a hydraulic motor to steer the vehicle wheel.

Abstract: A pneumatically operated speed governor (26) moves an engine throttle member (10) for controlling the speed of a vehicle. The governor includes a pneumatically operated actuator having an output connected to the engine throttle member. A pivotally mounted valve member (44) is positioned intermediate a vacuum supply orifice (46) and an atmospheric air orifice (48) and supplies a pneumatic signal to the actuator. An internal speed sensor (82) responsive to vehicle speed has an output member (100) which reacts against an improved, self-wiping minimum speed switch (102) and a set-speed control member (52) which in turn reacts against the pivotally mounted valve member (44) for varying the position of the valve member as the vehicle speed tends to fall below or rise above a predetermined set speed.

Abstract: A regulating device for a hydrostatic drive unit such as a hydropiston pump is provided with an adjusting piston designed as a differential piston, connected with the final control element of the drive unit and/or the pump and under pressure from both sides, and with a control valve controlling the pressure exerted on the adjusting piston in the pressure spaces in front of the end faces and with a control pressure gauge piston arranged in a sliding manner in the housing and on which the working pressure of the drive unit and/or feed pressure of the pump is exerted, and which lies against a lever, which is connected through a flexible coupling with the adjusting piston and is supported on this latter and is forced against it by a spring and actuates the control valve, in which case the control valve is located in the adjusting piston crosswise to its longitudinal axis, characterized in that the lever is designed as an angle lever and that the spring is located in the adjusting piston and lies against the secti

Abstract: A pneumatically operated speed governor (26) for moving an engine throttle member (10) for controlling the speed of a vehicle includes a pneumatically operated actuator having an output connected to the engine throttle member. A pivotally mounted valve member (44) is positioned intermediate a vacuum supply orifice (46) and an atmospheric air orifice (48) and supplies a pneumatic signal to the actuator. An inertial speed sensor (82) responsive to vehicle speed has an output member (100) which reacts against an improved, self-wiping minimum speed switch (102) and a set-speed control member (52) which in turn reacts against the pivotally mounted valve member (44) for varying the position of the valve member as the vehicle speed tends to fall below or rise above a predetermined set speed.

Abstract: A positioning apparatus includes a master hydraulic positioning cylinder having a relatively long stroke capability and a train of additively connected, short-stroke pneumatic control cylinders for controlling the length of stroke of the master cylinder and thus the positioning of a variable-position tool such as a band saw. One end of the cylinder train is connected by a feedback rod to an extensible portion of the master cylinder. A connecting rod connects the opposite end of the train directly to the spool of a three-position servo valve which controls the flow of hydraulic fluid to and from opposite sides of the master cylinder. When air pressure is admitted to a selected side of a selected control cylinder, at least a portion of the train shifts initially in a direction to move the servo valve to an operating position to begin stroking the master cylinder in a desired direction.