Temperature, ambient - The temperature of the environment in which an apparatus is working.

Tensile strength - Force in pounds per square inch required to cause the rupture of a specimen of a rubber material.

Terpolymer - A polymer consisting of three different monomers chemically combined.

Tie rod - An axial external cylinder element which traverses the length of the cylinder. It is prestressed at assembly to hold the ends of the cylinder against the tubing. Tie rod extensions can be a mounting device.

Torque motor - A type of electromechanical transducer having rotary motion used in the input stages of servovalves.

Torque - Rotary force transmitted by the driving shaft of the pump.

Torr - A unit of pressure equal to 1/760 of an atmosphere.

Torricelli's Theorem - The liquid velocity at an outlet discharging into the free atmosphere is proportional to the square root of the head.

Transducer, flow - A device which converts fluid flow to an electrical signal.

Transducer, pressure - A device which converts fluid pressure to an electrical signal.

Trunnion - A mounting device consisting of a pair of opposite projecting cylindrical pivots. The cylindrical pivot pins are at right angle or normal to the piston rod centerline to permit the cylinder to swing in a plane.

Tube - A conductor whose size is its outside diameter. Tube is available in varied wall thickness and material.

Vacuum - Pressure less than ambient atmospheric pressure.

Vacuum pump - A device which uses mechanical force and motion to evacuate gas from a connected chamber to create subatmospheric pressure.

Valve - A device which controls fluid flow direction, pressure or flow rate.

Valve actuator - The valve part(s) through which force is applied to move or position flow-directing elements.

Valve, air - A valve for controlling air.

Valve, cartridge - A valve with working parts contained in a cylindrical body. The cylindrical body must be inserted into a housing for use. Ports through the body cooperate with ports in the containing housing.

Valve, directional control - A valve whose primary function is to direct or prevent flow through selected passages.

Valve, directional control, 3-way - A directional control valve whose primary function is to pressurize and exhaust a port.

Valve, directional control, 4-way - A directional control valve whose primary function is to pressurize and exhaust two ports.

Valve, directional control, check - A directional control valve which permits flow of fluid in only one direction.

Valve, directly operated - A valve in which the controlling forces acting on the element directly influence the movement of the control elements.

Valve, electrohydraulic, proportional - A valve which responds proportionally to input signals.

Valve, flow control (flow metering) - A valve whose primary function is to control flow rate.

Valve, flow control, bypass - A pressure compensated flow control valve which regulates the working flow diverting surplus fluid to reservoir or to a second service.

Valve, flow control, deceleration - A flow control valve which gradually reduces flow rate to provide deceleration.

Valve, flow control, pressure compensated - A flow control valve which controls the rate of flow independent of system pressure.

Valve, flow dividing, pressure compensated - A flow dividing valve which divides the flow at a constant ratio regardless of the difference in the resistances of the branches.

Valve, flow dividing - A valve which divides the flow from a single source into two or more branches.

Valve, hydraulic - A valve for controlling liquid.

Valve, needle - A flow control valve in which the adjustable control element is a tapered needle. Its usual purpose is the accurate control of the rate of volume of flow.

Valve, pilot operated (indirect) - A valve in which a relatively small flow through an integral vent line relief (pilot) controls the movement of the main element.

Valve, pilot - A valve applied to operate another valve or control.

Volume change - A change in the volume of a seal as a result of immersion in a fluid expressed as a percentage of the original volume.

Vulcanization - A thermo-setting reaction involving the use of heat and pressure, resulting in greatly increased strength and elasticity of rubber-like materials.