Glossary

Gain Margin - The amount of control loop gain in decibels that can be increased before the system reaches instability.

Galling - An adhesion condition which arises from a combination of materials which possess either poor bearing characteristics or are operated with improper or no lubrication. This wear mechanism results in the transfer of material from one member to the other member in such a manner as to cause extremely high force to move the members relative to each other. Galling can result in both members virtually locked together.

Gauge Pressure - Pressure of a system over and above atmospheric pressure. The difference between absolute pressure and atmospheric pressure. It is the pressure used to calculate the forces exerted in a hydraulic system.

Generated Contaminant - It is contaminant produced due to the deterioration of surfaces, various tribological wear mechanisms, incompatible materials, etc. A product of system activity and inactivity.

Gland - The cavity of a stuffing box.

Heat Exchanger - A device attached to the oil reservoir to circulate water or air to keep oil at proper operating temperature.

Heated Platens - These are plates that have heating capabilities. They can be heated using electric rods, steam, oil, water or other medium. These system usually require thermal breaks between theheated plates and the hydraulic press structure. Heating controls can be separate or fully integrated into the press control system.

H-Frame Hydraulic Press - Commonly known as a 4 column hydraulic press, an H-Frame hydraulic press has a construction style that resembles the letter H. An H-frame hydraulic press can typically field multiple press applications simultaneously. TMP manufactures a complete H-frame hydraulic press line from 3-200 tons, serving the rubber, plastics, composite, and printed circuit board markets.

Horsepower - A standard unit of power or work. One Hp is equal to 550 ft lb. of energy or work done per second, 33,000 ft lb. of work per minute, 0.746 KW, or 42.4 BTU per minute.

Hydraulic Balance - A condition of equal opposed hydraulic forces acting on an element in a hydraulic component. That is, a condition in which opposing hydraulic forces are equal.

Hydraulic Detent - A valve configuration which applies the open actuator port pressure against an axial control surface of the spool to hold the valve spool position until a greater axial force is applied to shift the valve in the opposite direction.

Hydraulic Fuse - A hydraulic fuse is designed to provide excess flow protection. It automatically shuts off any line in which failure (component rupture or fracture) has occurred and where hydraulic fluid spews out of a system. It is analogous to an electrical safety device called a "fuse" in which a strip of metal melts and interrupts the circuit when the current exceeds a particular amperage. These devices consist of various types of excess-flow valves. Such devices are used to block flow and not to relieve pressure as performed by a hydraulic system protector.

Hydrokinetics - The engineering science pertaining to the forces produced by a liquid as a result of its motion. For example a centrifugal pump.

Hydrolytic Stability - The resistance to permanent changes in properties caused by chemical reaction with water.