Glossary and index of fluid power principles and components L
LAG
Preferred engineering term for delay in response (usually in degrees).
LAMINAR FLOW
A condition of flow in a passage that is typified by slow movement of fluid in a relatively straight path along the centerline of a passage. See TURBULENT FLOW.
LEVEL TRANSMITTER
An electro-mechanical device which senses the level of fluid in a chamber and produces an analog signal that corresponds with the change of state in the chamber. See LEVEL SWITCH.
LEVEL SWITCH
An electro-mechanical device which senses the level of fluid in a chamber and opens or closes a digital switch to indicate a change of state. See LEVEL TRANSMITTER.
LEVERAGE
A gain in output force over input force by sacrificing the distance moved. Mechanical advantage or force multiplication.
LIFT
The measure of the capability of a pump to raise fluid from a lower to higher level at its inlet port without damage to the pump. Normally expressed in feet of water.
LINE
A connection between components, a passage for fluid or gas transfer. See PIPE, and TUBE and HOSE.
LINEAR ACTUATOR
A device for converting hydraulic energy into linear motion, i.e. a cylinder or ram.
LINEAR VARIABLE TRANSFORMER (LVT)
An electro-mechanical linear device that produces an analog signal in proportion to the difference in velocity between a magnet and a separate fixed coil.
LINEAR VARIABLE DIFFERENTIAL TRANSFORMER (LVDT)
An electro-mechanical linear device that produces an analog signal in proportion to the difference in distance between a magnet and separate fixed coil.
LINEARITY (SERVOVALVE)
The degree of straightness of the hysteresis plot.
LIQUID LEVEL GAUGE
Gauge to visually indicate the fluid level in a reservoir or tank.
LITER
A metric measure of volume. One (1) liter = 0.2642 gallons.
LOGIC CIRCUIT
A digital circuit (also called a gate) that has binary inputs and outputs and is capable of performing a decision making function.
LOOP INSTALLATION
The assembly is installed in a loop or “U” shape and is most often used when frequent and/or large amounts of motion are involved.
LUBRICATOR
A mechanical device which is used to inject drops or mist of oil into an air line for lubrication purposes.