Monthly Archives for July 2013

Hydraulic Motors

Hydraulic motors can be used to convert the controlled fluid power from a valve or pump into rota.ting mechanical power for driving a load. The Buid Bow is changed to rotational velocity or speed, and the pressure is converted into … Continue reading

22. July 2013 by Jack
Categories: Hydraulic Motor | Tags: | Leave a comment

Variable Displacement Pump Flow and Pressure Characteristics

Generally, the flow and pressure characteristics of variable-displacement pumps are given as constants assuming linear characteristics. As stated before, for high-pressure operation with low-viscosity fluids, the pump characteristics may become more nonlinear. In this case, the nonlinearities should be considered … Continue reading

22. July 2013 by Jack
Categories: Hydraulic Pumps | Tags: | Leave a comment

Variable Displacement Pump Leakage Characteristics

If the pump is driven at constant speed, the flow from the pump is directly proportional to the pump stroke. The output pressure or discharge pressure from the pump is determined by the load or the restriction to the pump … Continue reading

22. July 2013 by Jack
Categories: Hydraulic Pumps | Tags: | Leave a comment

VARIABLE-DISPLACEMENT PUMPS

In servo control systems, the variable-displacement or servo pump performs the same basic function as the control valve. However, the servo pump generates the controlled fluid power as demanded in response to an input control signal. In most applications, the … Continue reading

22. July 2013 by Jack
Categories: Hydraulic Pumps | Tags: , | Leave a comment

Jet Control Valves

The principle of converting pressure into kinetic energy and then reconverting this energy into a controlled pressure can be utilized as a control means. The various types of jet control valves use this mode of operation. Proportional control is obtained … Continue reading

22. July 2013 by Jack
Categories: Pressure Control Valves | Tags: | 1 comment

Four-way Flapper-nozzle Control Valve

The four-way flapper-nozzle valve has two identical hydraulic circuits, one supplies flow and pressure to one side of an actuator, the other circuit supplies the hydraulic fluid to the other side of the actuator. In other words l the valve … Continue reading

22. July 2013 by Jack
Categories: Directional Control Valves | Tags: | Leave a comment

Three-way Flapper-nozzle Control Valve

The flapper-nozzle valve has certain mechanical design advantages mainly the simpler construction and the feature of no close-clearance sliding parts as compared to the spool-type valves. However, flapper nozzle valves must be very .accurately designed to provide characteristics which exactly … Continue reading

10. July 2013 by Jack
Categories: Directional Control Valves | Tags: | Leave a comment

Two-way Valve Constant-flow Source Characteristic

The two-way valve is merely a throttling valve having one variable-area orifice. When used in conjunction with a constant-flow source, the two-way valve can be used to position a piston actuator &s shown by Fig. 1.22. As indicated, a return … Continue reading

10. July 2013 by Jack
Categories: Directional Control Valves | Tags: | Leave a comment

Three-way Valve Constant-pressure Source Characteristic

The three-way control valve uses only one control pressure line to the actuator with the normal pressure supply line and a drain or return line. This type of valve is illustrated by Fig. 1.20. As can be noticed, the valve … Continue reading

10. July 2013 by Jack
Categories: Directional Control Valves | Tags: | Leave a comment

Four-way Open-center Hydraulic Valve

When a valve is designed to use a constant-flow source of fluid, the valve does not have its cont.rolling edges covering their corresponding port edges. Instead, each port edge is uncovered in the centered valve position. This type of valve … Continue reading

03. July 2013 by Jack
Categories: Directional Control Valves | Tags: | Leave a comment