Glossary and index of fluid power principles and components E

ECCENTRIC WALL
A wall of varying thickness

ECCENTRICITY
The condition resulting from the inside and the outside diameters not having a common center. See eccentric wall.

EFFICIENCY
The ratio of output to input. Volumetric efficiency of a pump is the actual output, in gpm, divided by the theoretical or design output. The overall efficiency of a hydraulic system is the output power divided by the input power. Efficiency is usually expressed as a percent.

EFFUSION
The escape, usually of gases, through a material. See permeation.

ELASTIC LIMIT
The limiting extent to which a body may be deformed and yet return to its original shape after removal of the deforming force.

ELASTOMER
Any one of a group of polymeric materials, usually designated thermoset, such as natural rubber, or thermoplastic, which will soften with application of heat.

ELECTRIC MOTOR
An electro-mechanical device that converts electrical power into rotary motion. The resultant power output is measured in horsepower

ELECTROHYDRAULIC SERVO-VALVE
A servo-valve which is capable of continuously controlling hydraulic output as a function of an electrical input.

ELECTROMAGNETIC INTERFERENCE (EMI)
A modification of signals contained in circuit wiring (or stored in a microprocessor) caused by a strong magnetic flied radiated from some other electrical or electronic device or conductor.

ELECTROMOTIVE FORCE (EMF)
The force produced by a difference of electrical potential that causes current to flow in circuit. EMF is measured in units called volts.

ELECTROSTATIC DISCHARGE
The sudden discharge of static electricity from an area of buildup to a grounding point.

ELEMENT
See FILTER ELEMENT

ELONGATION
The increase in length expresses numerically as a percentage of the initial length.

ENCLOSURE
A rectangle drawn around a graphical component or components to indicate the limits of an assembly.

ENDURANCE TEST
A service or laboratory test conducted to product failure, usually under normal use conditions

ENERGY
See JOULE.

EPDM
Ethylene Propylene Diene Monomer; an elastomer.

EROSION
Degradation of a surface which is the result of mixtures of fluid and air or fluid and dirt particles passing over the surface at the same time as a change in pressure occurs.

ERROR (SIGNAL)
The signal which is the algebraic summation of an input signal and feedback signal.

EXHAUST LINE
A passage that is open to atmosphere. Normally used in systems using pressurized air or gas which may be dispersed into the atmosphere.

EXTRUDE/EXTRUDED/EXTRUSION
Forced through the shaping die of an extruder; extrusion may have a solid or hollow cross section.