Monthly Archives for December 2010

Mechanical Hydraulic Servo Circuit

Figure 10.10 shows a mechanical hydraulic servo system with automotive power steering, the sequential operation of which occurs as follows: • The input or command signal is the turning of the steering wheel. • This results in movement of the … Continue reading

23. December 2010 by and
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Hydraulic Fail-Safe Circuit

Fail-safe circuits are basically designed to prevent injury to the operator or damage to the equipment. In general they prevent any accidental fall or overloading of the equipment. Figure 10.7 shows a fail-safe circuit in which the cylinder is prevented … Continue reading

23. December 2010 by and
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Hydraulic Cylinder Sequencing Circuit

From our earlier discussions, we have seen how a sequence valve can be used to create sequential operations in a hydraulic circuit. The circuit depicted in Figure 10.6 contains a hydraulic system in which two sequence valves are used to … Continue reading

23. December 2010 by and
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Counterbalance Valve Application

Figure 10.5 illustrates the use of a counterbalance or backpressure valve to keep a vertically mounted cylinder in upward position during pump idling. The counterbalance valve is set to open at a pressure slightly above the pressure required to hold … Continue reading

23. December 2010 by and
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Water Cooled Hydraulic Heat Exchanger

Figure 7.26 is an illustration of a common type of water-cooled heat exchanger used in hydraulic systems. This is typically a shell and tube-type heat exchanger. The cooling water is pumped into the heat exchanger and flows around the tube … Continue reading

23. December 2010 by and
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Air Cooled Hydraulic Heat Exchanger

Figure 7.25 shows an air-cooled heat exchanger. The hydraulic fluid to be cooled is pumped through the tubes that are finned. As the fluid flows through the tubes, air is blown over them. This takes away the heat from the … Continue reading

23. December 2010 by and
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Hydraulic Heat Exchangers

Heat is generated in a hydraulic system because of the simple reason that no component can operate at 100% efficiency. Significant sources of heat include pumps, pressure relief valves and flow control valves. This can cause a rise in temperature … Continue reading

23. December 2010 by and
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Hydraulic Accumulator as Leakage Compensator

In this application (Figure 7.23), the accumulator acts as a compensator, by compensating for losses due to internal or external leakage that might occur during an extended period of time, when the system is pressurized, but not in operation. The … Continue reading

23. December 2010 by and
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Accumulator Auxiliary Power Source

This is one of the most common applications of an accumulator. In this application, the purpose of the accumulator is to store the oil delivered by the pump during the work cycle. The accumulator then releases the stored oil on … Continue reading

23. December 2010 by and
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Bladder Type Separator Gas Loaded Hydraulic Accumulator

The bladder-type accumulator contains an elastic barrier between the oil and gas as shown in the cross-sectional view in (Figure 7.20). The bladder is fitted to the accumulator by means of a vulcanized gas-valve element that can be installed or … Continue reading

23. December 2010 by and
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