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Piston Pumps and Control Valves for Hydraulic Systems

Hydraulic systems can incorporate different types of pumps and control valves, depending on whether the system is open-loop or closed-loop in design. It is essential to select the correct methods for generating pressure and flow control as needed to achieve the desired tasks the system is designed to perform.

Piston Pumps

Piston pumps are one type of pump you might use as part of your system design. This type of pump is considered a positive displacement pump. This type of pump provides relatively no slippage compared to the volume of fluid output. It works on the principle of positive displacement.

This principle is where the pump displaces the same amount of fluid for every rotation of the pump. Continued fluid movement during multiple cycles is possible due to the higher tolerances between the pumping case and pumping mechanism. The movement of fluid through the system during each rotation remains fairly constant.

Even if there are changes in pressure, the amount of fluid moving through the pump and system will not generally change. However, it is worth noting, if you have a piston pump that is not operating correctly, or there is excessive slippage, it indicates something is wrong with the pump and it either needs to be repaired or replaced.

As such, piston pumps can be configured to provide both variable and fixed displacement during pumping cycles. In a variable configuration, the output is changed by altering the amount of fluid moving through the displacement chamber. In a fixed configuration, the output remains constant since the amount of fluid moving through the displacement chamber does not change.

Piston pumps are designed using the general principles of the reciprocating pump. A reciprocating pump generates pressure by using a piston inside a sealed cylinder chamber with a flow inlet and flow outlet. As the piston retracts, it draws fluid into the chamber.

Once the chamber is full of fluid, the piston pushes the fluid out through the flow outlet to generate pressure. As the fluid moves out of the chamber, pressure is generated as the volume of fluid becomes progressively smaller.

In a piston pump, many cylinders and pistons are used in place of a single cylinder and piston. The pistons and cylinders are often arranged in a circular pattern around a rotating unit and powered by connecting the rotary housing to a driveshaft. As the driveshaft turns, it rotates the rotary unit, which, in turn, causes the pistons and cylinders to also move.

As part of the rotary mechanism moves, the reciprocating pump motions are produced. The pistons move up or down inside the cylinders to draw in or expel fluid. As a result, flow and pressure are generated.

There are two general types of piston pumps: radial piston pumps and axial piston pumps. Both types of pumps can be configured as either variable or fixed displacement pumps. In addition, certain models of radial piston pumps can be configured to provide variable, over-center, reversible displacement.

The variable piston pump designs are normally larger in comparison to fixed piston pump designs. This is due to the addition of various controls required for varying displacement, including electric motors, servo motors, hydraulic cylinders, hand wheels, and so on.

Radial pump designs have the pistons placed radially within the housing on the cylinder block. As the pump moves, the pistons move perpendicular to the center of the driveshaft. There are two basic designs, which are either one that uses ball-shaped pistons, or the other, which uses cylinder-shaped pistons. Radial piston pumps can also be described by using the arrangement of the ports on the pump, which normally uses either pintle valves or check valves.

Axial pump designs are slightly different in the placement of the cylinders and pistons inside the housing. In this design, the pistons move parallel to the center of the driveshaft. The design uses port plates, control valves, and/or check valves to help direct the movement of the fluid as it is drawn into the pump until it is pumped out. One of the most basic axial pump designs is the inline piston pump.

Piston pumps are used in a variety of different hydraulic systems. The pressure they generate can be used to operate heavy equipment and machinery. In addition, they can be used for smaller-scale applications, like in automobiles, paint sprayers, pressure washers, and so on.

Control Valves

Control valves are another type of component that can be found in hydraulic systems. These valves help regulate and direct the flow of fluid through the system. Depending on the type and their design, they can alter the size of the passages the fluid can flow through, alter pressure in the system, alter the direction of flow, and alter flow rates. There are three general types of control valves:

• Flow Control Valves: This valve regulates fluid flow rates by automatically altering the size of the openings within the valve the fluid will flow through.
• Direction Control Valves: This valve ensures fluid is moving in the desired direction. Some styles are referred to as check valves and keep fluid moving in one direction while preventing it from flowing backwards.
• Pressure Control Valves: This valve controls, switches, and regulates the desired pressure, which can be altered by making adjustments to the valve.

Each type of control valve is available in various configurations to work with various systems, from inline to flanged and sub-plate mounting options, based on where they are required in the system. Based on their placement, the control valves will operate differently and provide various functions.

Control valves can be controlled electronically or manually, depending on the complexity of the system. The positioning of the valves can be regulated by other attached components, in addition to actuators, and it may include temperature gauges, flow meters, and so on.

Control valves can be found in numerous types of hydraulic systems, as well as used alongside various pumps, including piston pumps in hydraulic braking systems, printing presses, construction equipment, and so on.

Similarities Between Piston Pumps and Control Valves

Both piston pumps and control valves provide a means to regulate and control the flow and pressure of fluid through a hydraulic system. They can be used in a variety of machines and equipment, as well as other applications that rely upon hydraulics. It is not uncommon for more complex systems to use piston pumps with a variety of different types of control valves.

Differences Between Piston Pumps and Control Valves

One key difference between the two is that piston pumps are generally powered by a rotating drive shaft connected to the pump. The speed at which the shaft rotates can vary, meaning the rotation speed of the pump can also be varied by increasing the speed at which the shaft rotates. The operation of control valves is regulated and controlled automatically using electronics and computerized functions or manually using a lever or switch.

In addition, control valves are an essential part of any system where hydraulics are being used. Even the simplest configurations have some type of control valves as part of the system design. In this way, control valves are different from piston pumps because they can be used with piston pumps, gear pumps, vane pumps, rotary pumps, and so on.

As you can see, hydraulic piston pumps and control valves provide useful purposes when used together in various configurations. As such, you need to determine what types of piston pumps and control valves will be the most beneficial as part of your hydraulic system.

For assistance in selecting the right piston pumps and control valves, or other hydraulic pumps, parts, and components, please feel free to contact White House Products Ltd. at +44 (0) 1475 742500 today!

We stock one of the most diverse selections of hydraulic components and supplies, including over 6,000 different specifications of oil hydraulic gear pumps. We supply the entire United Kingdom with mostly next-day service and provide fast shipment to over one hundred countries worldwide.

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