Glossary

Lapping-in - Its polishing a surface so that valve seat obtains a smooth mating surface. .

Lap - It's a relative axial position relationship between fixed and movable flow metering edges with spool at null. Here, Lap is measured as total separation at zero flow of straight line extension of nearly straight portions of normal flow curve that are drawn separately for each polarity and are expressed as per cent of rated input parameter. .

Leakage, Center Position - It refers to amount of leakage that is associated with spool lap conditions for given clearance. .

Learning Control System - It's a system that is designed for recognizing familiar features as well as patterns of situation and then, based on its past experience/learned behavior, reacting in an optimum manner. .

Linear Actuator - It's a device that converts pressure energy into linear motion with limited stroke like a hydraulic cylinder or ram. .

Linear Equation (Function) - It's a equation of first degree that always maps as straight line. .

Linearity - It's a measure of deviation from proportional relationship in ratio of valve output to input where the degree to which normal flow curve conforms to normal flow gain line with other operational variables that are held constant. Here, when output varies in direct proportion to input, valve is considered linear. .

Load Sensing System - It's a closed-circuit system with load/pressure feedback and combines advantages of open-center system as well as constant pressure closed-center systems while avoiding their major disadvantages. .

Lumped Parameter Model - it's a mathematical model that treats all variables of system element (lumped) as if they acted at only one point in element. The converse is distributed system. M Magnetic Lock - It's a motion impediment that is produced by unshielded magnetic field which attracts and accumulates ferromagnetic particles that induce surface lockup. .

Manual Override - It means manually operating automatic control. .

Micron (or Micrometer) - Its one thousandth part of one mm, 0.0000394-in., or one-millionth of a meter and is used as a common unit used when specifying filters, sieves and screens. .

Modulus, Rubber (or Elastomer) - Its stress level at predetermined elongation, usually reported at 100% and is a good indicator of compound toughness and at given hardness, high modulus generally means good anti-extrusion as well as dynamic characteristics. .

Motor, Fixed-displacement - It's a rotary motor where displacement per revolution is not adjustable. .

Motor, Rotary - It's a motor capable of making continuous rotary motion and producing output torque proportional to displacement per revolution and pressure drop between intake and discharge ports. .

Motor, Variable-displacement - It's a rotary motor where displacement per revolution is adjustable. N Natural Frequency - It's the frequency of cycling motion of undamped second-order component. For transient-response curve, frequency of cycling which deviation would have if the response were undamped. Also frequency at which object would vibrate at zero damping. On Bode Plot of second-order system, it is frequency where extension of final slope of response curves that intersects 0-db line of amplitude ratio. .