VocabulaWry Term - Copy

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<p>Vocabulary TermDefinition</p> <p>AccumulatorA hydraulic component used to store hydraulic fluid and pressure. An acccumulator can be used as a backup power source, a leakage compensator, and a shock absorber.</p> <p>Bleed-Off CircuitA flow control configuration in which a valve directs flow back to the tank when actuated. The valve of the bleed-off circuit can be located anywhere along the main line.</p> <p>BoosterA hydraulic component that converts low pressure from a large area of the booster into high pressure in a small area of the booster. Also called an intensifier, a booster is usually two different-sized cylinders connected by a common piston.</p> <p>Cam-OperatedActuated by the distinct physical geometry of a cam, or a circular shape that converts rotational movement into linear movement. As the cam rotates, its shape actuates the valving mechanism of the valve.</p> <p>Double-Acting CylinderA fluid power actuator that directs energy in two directions.</p> <p>ExtensionThe movement of a single-acting cylinder characterized by fluid pushing on the piston and moving the rod outside of the cylinder housing. In a double-acting cylinder, extension occurs on each stroke and alternates between ends of the cylinder.</p> <p>FilterA screen used for limiting contamination by trapping very fine and fine particulate matter.</p> <p>Flow Control ValveA fluid component that controls the rate of fluid flow. Flow control valves make it possible to control other system variables like the speed of an actuator.</p> <p>High-Low CircuitA hydraulic circuit powered at different times by a high-pressure, low-flow pump and a low-pressure, high-flow pump. This two-pump circuit configuration eliminates the need for a relatively expensive high-pressure, high-flow pump and also saves energy.</p> <p>Hydraulic IntensifierA hydraulic component that converts low pressure from a large area of the intensifier into high pressure in a small area of the intensifier. Also called boosters, intensifiers are usually two different-sized cylinders connected by a common piston.</p> <p>In ParallelA circuit configuration in which fluid flows into the cap end of two or more side-by-side cylinders from the same source at the same time. Although the cylinders will move, it is impossible to synchronize them.</p> <p>In SeriesA circuit configuration in which cylinders are connected end-to-end. In this configuration, all cylinders are synchronized regardless of the load on any individual cylinder.</p> <p>Independent Filter CircuitA secondary fluid circuit intended solely for filtering the fluid for another circuit.</p> <p>Kidney Loop FilterA filter located on an independent circuit intended only for filtration. The kidney loop filter shares a common reservoir with the main circuit.</p> <p>LogicThe unique configuration of a hydraulic circuit that involves placing components to perform work.</p> <p>LungingA situation in which the actuator and the load are moving in the same direction. Lunging, or overrunning, often causes the actuator to jump.</p> <p>Meter-In CircuitA flow control configuration in which the valve is located downstream of the pump and upstream of the actuator.</p> <p>Meter-Out CircuitA flow control configuration in which the valve is located downstream of the actuator.</p> <p>Pilot Check ValveA check valve that is direct-operated under normal circumstances and actuated by a pilot signal under circumstances that call for a valve override.</p> <p>PositionThe number of physical settings on a directional control valve. A three-position valve can be placed in three different physical settings with a control such as a lever.</p> <p>Pressure DropThe difference between two pressure levels in a hydraulic circuit.</p> <p>Pressure Line Bleed-Off FilterA filter located on a secondary line connected to the main line at the outlet of the pump.</p> <p>Pressure Line FilterA filter located at the outlet of the pump.</p> <p>ReciprocationThe back-and-forth extension and retraction of a hydraulic cylinder.</p> <p>RetractionThe movement of a single-acting cylinder characterized by fluid exiting the cylinder and the rod moving into the cylinder housing. In a double-acting cylinder, retraction occurs on each stroke and alternates between ends of the cylinder.</p> <p>Return Line FilterA filter located on the return line just before the line enters the reservoir.</p> <p>Rod EndThe side of the piston that is attached to the rod.</p> <p>Sequence ValveA pressure control valve that allows hydraulic fluid to flow into a secondary system after a critical pressure is reached.</p> <p>Single-Acting CylinderA fluid power actuator that directs energy in one direction.</p> <p>Spring-CenteredSituated by a mechanism that keeps a directional control valve in the center locked position unless the valve is actuated into the first or third position.</p> <p>Suction Line FilterA filter located between the reservoir and the pump.</p> <p>Unloading ValveA pressure relief valve located near a pump in order to depressurize the pump when a critical pressure downstream has been reached.</p> <p>Variable Feed CircuitA flow control configuration in which a cam-operated two-way valve and a meter-out flow control valve are located in parallel. This results in varying speeds at different parts of the circuit.</p> <p>Water HammerShock in a hydraulic system that can cause damage to components if not addressed.</p> <p>WayA characteristic of a valve that indicates how a fluid can flow through it.</p> <p>One major problem confronting the meter-out operation is the intensification of pressure in the circuit which can in turn occur on account of a substantialdifferentialarea ratio between the piston and the rods. Pressure intensification occurs on the rod side when the meter-out operation is carried out without a load on the rod side of the cylinder and can result in failure of the rod seals. It is therefore seen that both the meter-in and meter-out operations have their relativeadvantagesand disadvantages and only the application determines the type and nature of flow valve placement.Hydraulic Meter-in Circuit{0Comments}Posted byandonJanuary 6, 2011inFluid FlowMeter-in is a method by which aflow controlvalve is placed in ahydrauliccircuit in such a manner that there is arestrictionin the amount of fluid flowing to the actuator. Figure 6.38(a) shows a meter-in operation in a hydraulic system.If theflow control valvewere not to be located, the extension and retraction of the actuator which in this case is a cylinder, would have proceeded at an unrestricted rate. The presence of the flowcontrol valveenables restriction in the fluid flow to the cylinder and thereby slowing down its extension. In the event of the flow direction being reversed, thecheck valveensures that the return flow bypasses the flow control valve. For the same meter-in operation, Figure 6.38(b) shows shifting of the flow control to the other line. This enables the actuator to extend at an unrestricted rate but conversely the flow to the actuator during the retracting operation can be restricted so that the operation takes place at a reduced rate. The meter-in operation is quite accurate with a positive load. But with an overrunning load over which the actuator has no control, the cylinder begins to cavitate.</p>