Knowledge Base Glossary

A wheel located at the top of a manually operated valve that is used to actuate the valve stem.

The resistance to indentation. This is measured by the relative resistance of the material to an indentor point of any one of a number of standard hardness testing instruments.

A piece of equipment designed to transfer thermal energy from one media to another. The unit is typically a long cylindrical body with multiple tubes passing within the body. Media of one temperature flows within the body but external to the tubes, while media of another temperature flows within the tubes, thus allowing thermal energy to exchange without cross-contamination of the products.

A needle roller radial bearing with a machined and ground channel-shaped outer ring with a complement of needle rollers, retained and guided by a cage. A heavy-duty needle roller bearing can only carry a radial load.

The circular, screw-like, up and/or down motion of a rod or valve stem.

Metal seal composed of a helical, wound spring with a single or double jacket wrapped around the spring. Cross-section of the seal is circular and various shapes and sizes can be created using different jacket wrappings.

A sealing level that does not exceed 1.0 x 10-9 atm cc/sec of Helium.

Of uniform composition throughout.

The standard unit of power in the imperial system. HP = (T in lbs) (RPM) / 63025

Amount of interference or clearance between bearing outside surface and housing bearing seat.

A packaged wheel-end unit that contains bearings, seals and all components necessary for easy installation. It is pre-sealed, pre-lubricated and pre-set for precise performance.

A metal cap that fits over the outer end of the hub to keep grease in and dirt out of the bearing assembly.

HVAC (heating, ventilating, and air conditioning; also heating, ventilation, and air conditioning) is the technology of indoor and vehicular environmental comfort. Its goal is to provide thermal comfort and acceptable indoor air quality.

That state of lubrication in which the shape and relative motion of the sliding surfaces cause the formation of a continuous fluid film under sufficient pressure to prevent any contact between the surfaces. It is commonly called fluid-film lubrication.

A dynamic sealing device which utilizes the viscous shear and inertia forces of the fluid; imparted by a helically grooved or ribbed seal lip, to generate a pressure differential that opposes fluid flow.