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Automatic Cylinder Reciprocating System

The hydraulic circuit shown in Fig. 1.8 produces continuous reciprocation of a double-acting cylinder using two sequence valves. Each sequence valve senses the completion of stroke by the corresponding build-up pressure. Each check valve and the corresponding pilot line prevent … Continue reading

01. June 2018 by Dan
Categories: Hydraulic Circuits | Leave a comment

Hydraulic Cylinder Sequencing Circuits

Hydraulic cylinders can be operated sequentially using a sequence valve. Figure 1.7 shows that two sequence valves are used to sequence the operation of two double-acting cylinders. When the DCV is actuated to its right-envelope mode, the bending cylinder (B) … Continue reading

01. June 2018 by Dan
Categories: Hydraulic Circuits | Leave a comment

Counterbalance Valve Application

A counterbalance valve (Fig. 1.6) is applied to create a back pressure or cushioning pressure on the underside of a vertically moving piston to prevent the suspended load from free falling because of gravity while it is still being lowered. … Continue reading

01. June 2018 by Dan
Categories: Hydraulic Circuits | Leave a comment

Control of a Single-Acting Hydraulic Cylinder

Figure 1.1 shows that the control of a single-acting,spring return cylinder using a three-way two-position manually actuated, spring offset direction-control valve (DCV). In the spring offset mode, full pump flow goes to the tank through the pressure-relief valve (PRV). The … Continue reading

01. June 2018 by Dan
Categories: Hydraulic Circuits | Leave a comment

Bleed-Off Circuit

Compared to meter-in and meter-out circuits, a bleed-off circuit is less commonly used. Figure 1.10 shows a bleed-off circuit with extend stroke control. In this type of flow control, an additional line is run through a flow-control valve back to … Continue reading

01. June 2018 by Dan
Categories: Hydraulic Circuits | Leave a comment

Meter-Out Circuit

Figure 1.9 shows a meter-out circuit for flow control during the extend stroke. When the cylinder extends, the flow coming from the pump into the cylinder is not controlled directly. However, the flow out of the cylinder is controlled using … Continue reading

01. June 2018 by Dan
Categories: Hydraulic Circuits | Leave a comment

Meter-In Circuit

Figure 1.8 shows a meter-in circuit with control of extend stroke. The inlet flow into the cylinder is controlled using a flow-control valve. In the return stroke, however, the fluid can bypass the needle valve and flow through the check … Continue reading

01. June 2018 by Dan
Categories: Hydraulic Circuits | Leave a comment

Pressure-Compensated Valves

Pressure-compensated flow-control valvesovercome the difficulty causedby non-pressure-compensated valves by changing the size of the orifice in relation to the changes in the system pressure. This is accomplished through a spring-loaded compensator spool that reduces the size of the orifice when … Continue reading

01. June 2018 by Dan
Categories: Flow Control Valves | Leave a comment

Non-Pressure-Compensated Valves

Non-pressure-compensated flow-control valves are used when the system pressure is relatively constant and motoring speeds are not too critical. The operating principle behind these valves is that the flow through an orifice remains constant if the pressure drop across it … Continue reading

01. June 2018 by Dan
Categories: Flow Control Valves | Leave a comment

Pilot-Operated Unloading Valve

A pilot-operated unloading valve has less pressure override than its direct-acting counterpart.So it does not dump part of the flow prematurely. A pilot-operated unloading relief valve is the same as a pilot-operated relief valve with the addition of an unloading … Continue reading

01. June 2018 by Dan
Categories: Pressure Control Valves | Leave a comment

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