Glossary

Closed Circuit - It's a conduit arrangement where pump delivery, after passing through hydraulic actuator, by-passes reservoir and returns directly to pump inlet. The closed circuit configuration is generally used for hydrostatic transmission drive systems. Here, the movement of actuator in this circuit is controlled by variable displacement pump and not through valve. .

Closed Loop - Its group of control elements that are linked together such that output is continually monitored as well as compared with inputs. Should output differ from input, resulting error signals cause corrective action in the system. .

C-Frame Hydraulic Press - Its also known as gap frame hydraulic press that has frame configuration resembling a "C." The C-frame hydraulic press is designed for having minimal footprint on shop floors. Other advantages of C-frame hydraulic press construction include increased open work area that increases accessibility. These hydraulic presses are also used for forming wide range of materials including plastics, composites and rubber. .

Capillary - It's a tube exhibiting length to diameter ratio ³ 400. In most cases tube has internal diameter in range of few thousandths of inch that causes characteristic elevation or depression of liquids. .

Cartridge Valve - It's a valve that can be removed as well as replaced easily without need of them getting fully dismantled. As these are completely bodiless, these are capable of satisfying directional, flow and pressure functions. .

Cartridge - Its a component that can be removed as well as replaced easily without being fully dismantled like a replaceable element for filter, pump or valve. .

Cavitation - It's a localized vaporous/gaseous condition where liquid stream occurs when pressure gets reduced below atmospheric and vapor pressure of liquid. In pumps, this situation occurs when suction line is restricted and resulting vacuum causes fluid to boil and surface of fluid wet component to flake and pit. .

Contamination Control - Its an engineering technology that is involved in planning, organizing and implementing all activities which are required for identifying (recognizing and describing) contaminants, analyzing (characterizing and quantifying) contaminants, excluding (restricting, isolating, and rejecting) contaminants, reducing (capturing, retaining, and removing) contaminants, establishing the tolerance of components for contaminants and also ascertaining necessary contaminants balance (between level of contamination in fluid and level of contaminant tolerance of components to yield given contaminant service life). D Dual Palm Button Controls - These are common methods of actuating hydraulic presses where both buttons are depressed at same time for bringing Ram down requiring operator to use both hands. Control circuits also include non-repeat and anti-tie down features. .

Distance Reversal Switch - These are adjustable limit switches required for setting depth of stroke at which ram reverses. .

Dwell Timer - Its an adjustable timer for setting length of dwell at bottom of stroke. The timer may be used for other functions like timing sequence of press movement. .

Dwell -Hydraulic Presses are cable of maintaining force on work for extended time periods. It is typically accomplished by using Pressure lock value/variable volume pumps that are remotely controlled for precise as well as long period of Pressure holding. .

Daylight - Its distance between bed bolster and Ram bolster when Ram is fully retracted. Its also commonly known as Open Height. .

Damping Length - Its horizontal distance between centers of incoming and outgoing flows in spool valve and is used in transient flow force analysis. Choose positive sign if fluid flows outward at metering orifice and negative sign otherwise. .

Derivative, Partial - It's a derivative taken with respect to single independent variable where all remaining independent variables are treated as constants. .

Distributed Parameter Model - It's a mathematical model that has infinite degree of freedom where variables can act over entire length of system elements. The converse is lumped model. .

Dither - Its a relatively high frequency, low amplitude periodic signal or oscillatory motion that is sometimes superimposed on servo valve input for bringing improvisation in system resolution. The dither (mechanically/hydraulically) is also applied to offset friction (static friction/silt lock), which promotes rapid and accurate response and/or improve system resolution. .

Double-acting - Its describes component like a cylinder that operates in two directions or where actuating force can be applied in either direction. E Effective Length of Rod - Its distance between load application point and cylinder resistance point. .