Category: Hydraulic Circuits

Fail-Safe Circuits

{0 Comments}

Fail-Safe Circuits

Fail-safe circuits are those designed to prevent injury to the operator or damage to the equipment. In general, they prevent the system from accidentally falling on an operator and also prevent overloading of the system. In following sections we shall discuss two fail-safe circuits: One is protection from inadvertent cylinder extension and other is fail-safe […]

Read More…

Speed Control of a Hydraulic Motor

{0 Comments}

Speed Control of a Hydraulic Motor

Figure 1.12 shows the speed control circuit of a hydraulic motor using a pressure-compensated FCV.The operation is as follows: – In a spring-centered position of the tandem four-way valve, the motor is hydraulically blocked. – When the valve is actuated to the left envelope, the motor rotates in one direction. Its speed can be varied […]

Read More…

Speed Control of a Hydraulic Cylinder

{0 Comments}

Speed Control of a Hydraulic Cylinder

The speed control of a hydraulic cylinder circuit can be done during the extension stroke using a flow-control valve (FCV). This is done on a meter-in circuit and meter-out circuit as shown in Fig. 1.11. Refer to Fig. 1.11(a). When the DCV is actuated, oil flows through the FCV to extend the cylinder. The extending […]

Read More…

Cylinders in Parallel

{0 Comments}

Cylinders in Parallel

Figure 1.10 shows a hydraulic circuit in which two cylinders are arranged in parallel. When the two cylinders are identical, the loads on the cylinders are identical, and then extension and retraction are synchronized. If the loads are not identical, the cylinder with smaller load extends first. Thus, the two cylinders are not synchronized. Practically, […]

Read More…

Locked Cylinder Using Pilot Check Valves

{0 Comments}

Locked Cylinder Using Pilot Check Valves

A check valve (Fig. 1.9) blocks flow in one direction but allows free flow in the opposite direction. A pilot-operated check valve permits flow in the normally blocked opposite direction when pilot pressure is applied at the pilot pressure port of the valve. Pilot-operated check valves are used to lock the cylinder, so that its […]

Read More…

Automatic Cylinder Reciprocating System

{0 Comments}

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 the shifting of the four-way valve until the particular stroke of the cylinder is completed. […]

Read More…

Hydraulic Cylinder Sequencing Circuits

{0 Comments}

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) retracts fully and then the clamp cylinder (A) retracts. This sequence of cylinder operation is […]

Read More…

Counterbalance Valve Application

{0 Comments}

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. Valve Operation (Lowering) The pressure setting on the counterbalance valve is set slightly higher than […]

Read More…

Double-Pump Hydraulic System

{0 Comments}

Double-Pump Hydraulic System

Figure 1.5 shows an application for an unloading valve. It is a circuit that uses a high-pressure, low-flow pump in conjunction with a low-pressure, high-flow pump. A typical application is a sheet metal punch press in which the hydraulic cylinder must extend rapidly over a great distance with low-pressure but high-flow requirements. This occurs under […]

Read More…
You might also likeclose