Category: Hydraulic Pressure Control

Hydraulic Pressure Switches

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Hydraulic Pressure Switches

A pressure switch is an instrument that automatically senses a change in pressure and opens or closes an electrical switching element, when a predetermined pressure point is reached. A pressure-sensing element is that part of a pressure switch that moves due to the change in pressure. There are oasically three types of sensing elements commonly …

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Hydraulic Fuses

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Hydraulic Fuses

A hydraulic fuse is analogous to an electric fuse and its application in a hydraulic system is much the same as that of an electric fuse in an electrical circuit. A simple illustration of a hydraulic fuse is shown in Figure 6.43. A hydraulic fuse when incorporated in a hydraulic system, prevents the hydraulic pressure …

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Hydraulic Sequence Valve Application

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Hydraulic Sequence Valve Application

Let us consider a hydraulic circuit in which two cylinders are used to execute two separate operations as shown in Figure 6.24. Now, let us assume that cylinder A is required to extend completely before cylinder B extends. This can be accomplished by placing a sequencing valve just before cylinder B as shown. The pressure …

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Hydraulic Sequence Valve

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Hydraulic Sequence Valve

A sequencing valve again is a normally closed pressure control valve used for ensuring a sequential operation in a hydraulic circuit, based on pressure. In other words, sequencing valves ensure the occurrence of one operation before the other. A sectional view of a sequencing valve is shown in Figure 6.23. When the components connected to …

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Hydraulic Compound Relief Valve

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Hydraulic Compound Relief Valve

A compound pressure relief valve is one which operates in two stages. They are designed to accommodate higher pressures than direct acting relief valves at the same flow rate capacity. To have a broad understanding of how a compound pressure relief is internally designed, a cutaway view of an actual valve manufactured by Vickers INC., …

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Hydraulic Pressure Control Applications

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Hydraulic Pressure Control Applications

1. A backhoe operator controls the speed of the cylinder, which extends the bucket by cracking open the DCV controlling flow of the cylinder. Describe the difference in the “feel” of the controls using the two different relief valves (a) and (b) shown in Fig. 3.31. 2. A 1.79-in3 displacement motor is turning at 804 …

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Hydraulic Brake Valve Application

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Hydraulic Brake Valve Application

A brake valve performs the same function as a counterbalance valve, but it is designed to overcome a key disadvantage. An example will illustrate this point. Suppose a direct-operated counterbalance valve is used in a motor circuit. There are times when the motor load can overrun, and braking is needed for those times. This valve …

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Hydraulic Counterbalance Valve Application

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Hydraulic Counterbalance Valve Application

The counterbalance valve, also called a holding valve, is used to prevent a weight from falling uncontrollably. As an example, consider a press with a two-ton platen (Fig. 3.27). When the directional control is shifted, the platen will fall unless there is a means for creating an opposing hydraulic force. A counterbalance valve accomplishes this …

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