Category: Fluid Flow

Hydraulic Meter-out Circuit

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Hydraulic Meter-out Circuit

In the meter-out operation shown in Figure 6.39, the direction of the flow through the circuit is simply changed as can be made out from the diagram. It is the opposite of a meter-in operation as this change in direction will cause the fluid leaving the actuator to be metered. The advantage with the meter-out […]

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Hydraulic Meter-in Circuit

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Meter-in is a method by which a flow control valve is placed in a hydraulic circuit in such a manner that there is a restriction in the amount of fluid flowing to the actuator. Figure 6.38(a) shows a meter-in operation in a hydraulic system. If the flow control valve were not to be located, the […]

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Pressure-compensated Flow Control Valves

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Pressure-compensated Flow Control Valves

Figure 6.35 illustrates the operation of a pressure-compensated valve. The design incorporates a hydrostat which maintains a constant 1.4kg/cm2 (20 psi) pressure differential across the throttle which is an orifice, whose area can be adjusted by an external knob setting. The orifice area setting determines the flow rate to be controlled. The hydrostat is normally […]

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Hydraulic Non-pressure-compensated Valve

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Hydraulic Non-pressure-compensated Valve

This type of valve is used where the system pressures are relatively constant and the motoring speeds are not too critical. They work on the principle that the flow through an orifice will be constant if the pressure drop remains constant. The figure of a non-pressure-compensated valve shown in Figure 6.34 also includes a check […]

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Hydraulic Ball Valves

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This is another type of flow control valve shown in Figure 6.31. It is made up of a ball with a through hole which is rotated inside a machined seat. The manner in which flow control is exercised can be understood better with the help of Figures 6.32(a) and (b). From Figure 6.32(a), it can […]

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Hydraulic Butterfly Valve

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This is another type of flow control valve. It consists of a large disk which is rotated inside a pipe, the restriction in flow being determined by the angle. Figure 6.30 shows a simple design of a butterfly valve. The advantage with this valve is that it can be constructed to almost any size. These […]

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Hydraulic Globe Valve

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This is the simplest form of a flow control valve. The globe valve gets its name from the disk element ‘globe’ that presses against the valve seat to close the valve. A simplified view of a globe valve has been illustrated in Figure 6.29. The fluid flow through the valve is at right angles to […]

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Hydraulic Flow Control Valves

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Hydraulic Flow Control Valves

A flow control valve is a device used for adjusting or manipulating the flow rate of a liquid or a gas in a pipeline. The valve contains a flow passage or a port whose flow area can be varied. The role of a flow control valve in a hydraulic circuit is very important and its […]

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Rotary Four-Way Directional Control Valves

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Rotary Four-Way Directional Control Valves

Although most direction control valves are of spool type design, other types are also used. One such design is the rotary four-way valve, which consists of a rotor closely fitted in the valve body. The passages in the rotor connect or block-off the ports in the valve body to provide the four flow paths. The […]

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Hydraulic Flow Control Valves

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Hydraulic Flow Control Valves

Flow control valves are used in constant-flow (fixed displacement pump) circuits to control actuator speed. The simplest type of flow control valve is a needle valve. Another name for a needle valve is a non-pressure-compensated flow control valve. Turning the manual adjustment on a needle valve causes the needle to move down into the orifice, […]

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