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Glossary of Terms - All Terms

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Glossary Subsets


• A unit of capacity in an electromagnetic system. A condenser is said to have a capacity of one farad if it will absorb one coulomb (one ampere per second) of electricity when subjected to a pressure of one volt.
• The unit of capacitan

Feedback Signal

The output signal from a feedback element. One example would be a motor used in conjuction with an encoder. The encoder supplies a feedback signal to the motor to precisely control motor speed.


A temperature scale. 32°F is the freezing point of water, 212°F is the boiling point of water.
• C° = (F° - 32) * (5/9)
• F° = (9/5) * C° + 32


Substances added to an adhesive to improve the ease of application or some specific performance property such as strength, hardness or other characteristic.

Fillet Radius

The corner dimension in a bearing housing that the bearings outer race corner radius must clear.

Filling Notch

A slot or notch cut in the shoulder of a ring to allow the loading of more balls into a bearing. This gives the bearing more load carrying capabilities.

Film Strength

A property of a lubricant that helps prevents the scuffing or scoring of metal parts.


The process of separating insoluble particulate matter from a fluid, such as air or liquid, by passing the fluid through a filter medium that will not allow the particulates to pass through it.


? A device whose primary function is the retention of insouluble contaminants from a fluid by a porous media. This keeps the oil free of contamination.
? An electrical device used to suppress electrical noise, or to improve the DC output to a DC motor.


A term usually applied to the last machining operation on any surface.

Fire Point

The temperature to which a combustible liquid must be heated so that the released vapor will burn continuously when ignited under specified conditions.

Fixed Bearing

A bearing which prohibits shaft axial movement in both directions.

Flash Point

The temperature which a combustible liquid must be heated to give off sufficient vapor to form a flammable mixture with air when a small flame is applied under specified conditions.


• The amount of internal clearance in a bearing.
• Also used to describe shaft and/or housing size and how they relate to the bore and/or outside diameter.


A condition where the pump inlet port is charged by placing the reservoir oil level above the pump inlet port.

Flow Control Valve

A valve which controls the rate of oil flow.

Floating Bearing

A bearing designed or mounted so as to permit axial movement between the shaft and housing.


A device which measures flow rate, total flow, or a combination of both.


• A liquid that is specially compounded for use as a power transmitting medium in a hydraulic system.
• Can refer to a liquid or gas.


A process designed to remove contamination from a fluid system.

Four-Way Valve

A directional valve having four flow paths.

Four Quadrant

Refers to a drive's ability to control the velocity and torque of a motor in either direction of rotation. The direction of torque can be in the opposite direction of the velocity for applications requiring braking or deceleration. Single-quadrant drive

Foam Inhibitor

An additive which causes foam to dissipate more rapidly.


The number of times an action occurs in a unit of time. Frequency is the basis of all sound. A pump or motor's basic frequency is equal to its speed in revolutions per second multiplied by the number of pumping chambers.


Any push or pull measured in units of weight. In hydraulics, total force is expressed by the product of pressure and the area of the surface on which the pressure acts.
• F = P x A

Front Connected

Piping connections are on exposed surfaces of hydraulic components.


The resisting force encountered at the common boundary between two bodies when one body moves or tends to move relative to the surface of the other body.

Flow Rate

The volume, mass, or weight of a fluid passing through a conductor per a given unit of time. This is normally expressed in gallons per minute (gpm).

Full Complement Bearing

A rolling bearing without cage in which sum of clearances between rolling elements in each row is less than the diameter of rolling elements and small enough to give satisfactory function of bearing.

Full Flow

In a filter, the condition where all the fluid must pass through the filter element.

Full Load Amps

The current flowing through a line terminal of a winding when rated voltage is applied at rated frequency with rated horsepower.

Full Load Current

The greatest current that a motor or other device is designed to carry under specific conditions. Anything additional is considered an overload.


An over-current protective device which consists of a conductor that melts and breaks when current exceeds rated value beyond a predetermined time.