Abstract: Precision in proportional operation of pinch valves along an application-specific path of opening and/or of closing is provided in proportionally controlled pinch valves, systems and methods. Included is the advantageous feature that pinch valves and pinch valve controlling systems and methods can be enhanced by carefully controlling not only two primary operational positions—either fully open or fully closed—but also in-between positions as are required for an application of a user of the pinch valve. The effect on the fluid flowing through tubing that is engaged by the pinch valve head between fully open and fully closed is considered, determined and used to achieve pinch valve operation that is linear in flow change and/or linear in pressure change along the closing path and/or opening path through the tubing. The pinch valves can include a normally closed port that opens when the system experiences a shut-down condition.

Abstract: A fluid flow control for controlling the speed of a piston in a fluid power cylinder is disclosed in which the flow control is located within the confines of the cylinder and includes a rotatable disk having tearshaped slots for communication of the exhaust fluid through the disk and out of the cylinder through discharge ports. Rotation of the disk to selectively position greater or lesser width portions of the tearshaped slot relative to an exhaust discharge opening in the cylinder permits selective, variable adjustment and throttling of the exhaust fluid to control the speed of movement of the piston in the cylinder.

Abstract: A logic selection circuit for selectively matching the transistor logic type of a first interfacing circuit with the transistor logic type of a second interfacing circuit. The logic selection circuit comprises a circuit latching means which latches the level of voltage signal present at the second interfacing circuit while receiving a signal from the first interfacing circuit. The logic selection circuit further comprises both an NPN transistor and a PNP transistor to ensure that the transistor logic type of the first interfacing circuit and the transistor logic type of the second interfacing circuit may be properly matched. The logic selection circuit disclosed may be utilized in a conventional magnetic proximity sensor which helps to control the movement of a piston within a cylinder.

Abstract: A leak test port plug device is disclosed which includes a resilient plug having a first portion which is substantially cylindrical and a second portion which is generally conical and formed in integral one-piece relationship to the first portion. When the first portion is inserted into a port of a component to be tested and the plug is compressed, the first portion radially expands in the port and the second conical portion moves into the end of the port to effectively seal the port against fluid leakage.

Abstract: An antibacklash rack and pinion assembly includes longitudinally movable first and second rack members which have gear teeth thereon which mesh with the gear teeth of the pinion gear. A spring exerts a force in the same longitudinal direction of the movement of the rack members and against one of the rack members so that that rack member moves longitudinally relative to the other rack member and the teeth of that rack member are offset from the teeth of the other rack member. Thereby, opposite sides of at least one tooth of the pinion gear at all times are simultaneously positioned between and held in engagement with at least one tooth on each of the rack members to prevent backlash on movement of the teeth.

Abstract: A cushioning system for a fluid power cylinder includes a first passage for the flow of fluid to and from the space between the piston and end cap closure of the cylinder, and a second passage including a throttling valve for throttling the flow of fluid from the space as the piston approaches the end cap closure to cushion the piston. An O-ring seal is centered in the first passage and relative to a seal actuating sleeve on the piston by a plurality of spaced projections extending outwardly from the O-ring. An improved method of forming the valve seat of the throttling valve is also disclosed, wherein the second passage is deformed to substantially conform to the width and shape of the throttling valve and provide substantially zero clearance between the valve and its valve seat.

Abstract: A cushioning system for a fluid power cylinder includes a first passage for the flow of fluid to and from the space between the piston and end cap closure of the cylinder, and a second passage including a throttling valve for throttling the flow of fluid from the space as the piston approaches the end cap closure to cushion the piston. An O-ring seal is centered in the first passage and relative to a seal actuating sleeve on the piston by a plurality of spaced projections extending outwardly from the O-ring. An improved method of forming the valve seat of the throttling valve is also disclosed, wherein the second passage is deformed to substantially conform to the width and shape of the throttling valve and provide substantially zero clearance between the valve and its valve seat.

Abstract: In order to preclude the entrapment of low pressure fluid in the interior of U-form seal members in the peripheral grooves of a piston for a fluid power cylinder and in turn prevent the inward deflection of such seals, there are provided cuts or notches in the edges of the end portions of the piston member to effect the venting of the inside of the seal members. Preferably opposing flat chord-like cuts are made in the end portions of the piston down to a mid part of the peripheral groove such that the resulting flat sections can be used to fit into wrench or vise means for piston rod assembly purposes.