Archive for May, 2019

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…

Regenerative Cylinder Circuit

{0 Comments}

Regenerative Cylinder Circuit

Figure 1.3 shows a regenerative circuit that is used to speed up the extending speed of a double-acting cylinder. The pipelines to both ends of the hydraulic cylinder are connected in parallel and one of the ports of the 4/3 valve is blockedby simply screwing a thread plug into the port opening. During retraction stroke, […]

Read More…

Pump-Unloading Circuit

{1 Comment}

Pump-Unloading Circuit

Figure 1.4 shows a hydraulic circuit to unload a pump using an unloading valve.When the cylinder reaches the end of its extension stroke, the pressure of oil rises because the check valve keeps the high-pressure oil. Due to high-pressure oil in the pilot line of the unloading valve, it opens and unloads the pump pressure […]

Read More…

Control of a Double-Acting Hydraulic Cylinder

{0 Comments}

Control of a Double-Acting Hydraulic Cylinder

The circuit diagram to control double-acting cylinder is shown in Fig. 1.2. The control of a double-acting hydraulic cylinder is described as follows: 1. When the 4/3 valve is in its neutral position (tandem design), the cylinder is hydraulically locked and the pump is unloaded back to the tank. 2. When the 4/3 valve is […]

Read More…

Simple Pressure-Relief Valve

{0 Comments}

Simple Pressure-Relief Valve

The most widely used type of pressure control valve is the pressure-relief valve because it is found in practically every hydraulic system. Schematic diagram of simple relief valve is shown in Fig. 1.1 and three-dimensional view is shown in Fig. 1.2. It is normally a closed valve whose function is to limit the pressure to […]

Read More…

Telescopic Cylinder

{0 Comments}

Telescopic Cylinder

A telescopic cylinder (shown in Fig. 1.6) is used when a long stroke length and a short retracted length are required. The telescopic cylinder extends in stages, each stage consisting of a sleeve that fits inside the previous stage. One application for this type of cylinder is raising a dump truck bed. Telescopic cylinders are […]

Read More…

Unloading Valves

{0 Comments}

Unloading valves are pressure-control devices that are used to dump excess fluid to the tank at little or no pressure. A common application is in high-low pump circuits where two pumps move an actuator at a high speed and low pressure.The circuit then shifts to a single pump providing a high pressure to perform work. […]

Read More…