Hydraulic Pumps Explained

Hydraulic pumps are an essential part of the modern world, with their usefulness cutting across several industries. Automotive, landscaping, construction, entertainment, aerospace, and the personal fitness industries use this essential piece of equipment in so many ways. Hydraulic pumps can allow you to achieve high levels of pressure with little effort while helping to promote precision and efficiency, giving you better control in the process. Infact, a typical hydraulic pump offers up to 90% efficiency. Also, hydraulic pumps consume less energy than other types of pumps to accomplish the same work, reducing maintenance costs significantly as a result. Hydraulic pumps offer immense benefits for many businesses. This article aims to shed more light on how they work, the types available, and other important information to help you make an informed purchasing decision for your business.

The function of a pump in a hydraulic system

If you’re interested in purchasing hydraulic pumps and need more information about them, this is hydraulic pumps explained.

The pump primarily produces liquid movement or flow in the hydraulic system. It does not necessarily generate the pressure needed. However, it produces the flow needed, which helps develop the necessary pressure. This is a function of resistance to fluid flow in the hydraulic system.

The hydraulic pump performs two major functions when in operation. First, the pump's mechanical action creates a vacuum at the pump inlet. This vacuum allows atmospheric pressure to force liquid from a reservoir to the pump through an inlet line. Secondly, this mechanical action causes the liquid to be delivered to the pump outlet and into the hydraulic system. The pump is responsible for supplying hydraulic flow to the other hydraulic system parts like the hydraulic cylinder, hydraulic motor, rams, etc.

How does a hydraulic pump work?

Hydraulic pumps use relatively the same operating or working principle as the other pumps. This operating principle is based on Pascal’s law which suggests that when pressure is applied to any fluid in an enclosed system, that fluid can be transmitted in all directions equally. Hydraulic energy requires flow and pressure to work perfectly. Without these two working together, performance cannot be achieved. The hydraulic pump’s role is to create the fluid movement needed to move the load. The pump archives this through some processes.

First, as mentioned previously, the pump creates a partial vacuum at the inlet through mechanical action. That creates an atmospheric pressure that forces the liquid into the pump’s inlet from the reservoir.

Secondly, its mechanical action delivers liquid into the pump outlet. This liquid is then forced into the hydraulic system. Here, most hydraulic pumps come with two check valves. One check valve is connected to the pump inlet while the other is connected to the pump discharge. The first check valve moves the fluid into the pump through it. The second check valve allows the fluid to move out or exit through the pump discharge.

The hydraulic fluid then delivers the fluid pressure into hydraulic motors, actuators, and cylinders at the required volume and pressure level. As a result, a flow is generated, producing more than enough pressure to overcome the flow of resistance.

What is the difference between open and closed centre hydraulics?

The terms ‘open and closed centre’ hydraulics refers to two different ways of reducing the pressure released to the pump. Two conditions are necessary to perform hydraulic workflow and pressure, as indicated previously. And the ability to control either flow or pressure is made possible through open or closed centre hydraulics.

  • The closed centre system: In this system, the turning of a pump creates the needed flow. To achieve a standby pressure at the directional control valve, enough flow is produced.
  • The open-centre hydraulic system: The flow is continuous with an open centre hydraulic system while the pressure remains intermittent. Here, the flow is generated and redirected to the cylinder through a central passage located within the directional control valve. When a directional control valve’s spool is stroked, pressure is created, and the flow becomes focused on the load. The load then begins to move when the pressure needed exceeds the load.

In most cases, while the closed centre system is more expensive, it’s considered to offer better efficiency and uses less energy. And this results in your business saving money on fuel costs. The open-centre hydraulic system is considered the less expensive option. That is mostly because a fixed displacement system is used, which is less expensive than the variable displacement option used in the closed centre hydraulic system.

What are the 3 types of hydraulic pumps?

Three main types of hydraulic pumps exist: gear, piston, and vane pumps. These are further classified based on their functions below.

Gear Pumps

A gear pump is considered a type of positive displacement pump. And it’s designed to move fluid by using interlocking cogs or gears to repeatedly enclose a fixed volume. A gear pump is commonly used to pump fluids at very high viscosity, for example, oil and paints. Gear pumps are also mostly preferred in applications where a high-pressure output or accurate dosing is required. Most gear pumps tend to run at much lower speeds as they do not need to generate centrifugal force. Their lower speed also makes them easier to control. Depending on various factors, their discharge pressure can be very high. Gear pumps also come in two main types; an external gear pump and an internal gear pump.

Piston Pumps

Piston pumps are the hydraulic pumps considered to have the best overall efficiency and the highest pressure rating. These pumps are designed to have very low fluid leakage, allowing them to operate at very high-efficiency levels in volume. Gear pump plungers may come with input or output channels, depending on the design. But in most cases, the design is pretty simple - consisting of a piston, a chamber, and two valves. Most piston hydraulic pumps are designed for oil and water hydraulics, pumping of liquids, high-pressure cleaning, and various industrial processing equipment.

Piston pumps can be used to move liquids or even compressed gases. But they can also be used to pump various media containing solid particles.

One major advantage of the piston hydraulic pump is that it offers greater efficiency. In addition to that, this type of pump can move fluid through a machine, regardless of viscosity. This pump also promises a very long performance life, only if they receive the right maintenance.

Vane Pumps

Vane hydraulic pumps are self-priming, positive displacement pumps that provide constant flow at varying pressures. They are designed to operate with a much lower flow pulsation. As a result, they operate at very low noise levels while offering constant flow. A vane pump uses a rotating cylinder with rotors or slots housing a series of vanes. These vanes then rotate inside a cavity, sliding in and out during each rotation. This in and out motion creates contracting and expanding volumes that push liquid through the pump.

Due to their design, vane pumps work well as high-pressure hydraulic pumps in the automobile industry. They are commonly used in automatic transmission pumps, air conditioning, power steering, and supercharging. But vane pumps can also be used in mid-range pressures and are great options for applications or machines like espresso coffee machines and carbonators for fountain soft drink dispensers.

Vane pumps offer two main advantages. First, they have a very high service life due to fewer tear and wear issues. And second, because they offer a balanced pump, they eliminate the laid on the bearing side, making it possible for high operating pressure to be used.

While the gear, piston, and vane pumps are the three main types of hydraulic pumps, there are further options such as electric, hand, and air-driven pumps. The electric-powered pumps, as the term suggests, are electric driven pumps. They’re designed to be lightweight and compact. This makes them ideal for powering small to medium-sized cylinders or hydraulic tools. Their lightweight design makes them ideal for applications that require easy transport of the pump, so keep this in mind.

Hand pumps are also designed to be lightweight and come in a compact form to make for very easy carrying. You can find two-speed, lightweight models of hand pumps that are easy to handle, reducing operator fatigue, as a result.

Otherwise known as air-powered pumps, air-driven pumps are mostly designed to deliver very high levels of efficiency. They also boast of enhanced productivity and proven reliability. Their construction makes it easy for them to provide high-quality performance, offering precise control and fine metering capabilities. Air-driven hydraulic pumps are mostly ideal for delivering compact air over hydraulic as well as offering or delivering higher oil flow.

If you’re looking to purchase hydraulic points or need further information about them, please do not hesitate to contact Worlifts for further assistance.