How Does a Hydraulic Pump Work?

03 February 2020
How Does a Hydraulic Pump Work?

Hydraulic pumps are common in mobile applications such as excavators, tractors, cranes, forestry equipment, loaders, forklifts and vacuum trucks. They are also used in many types of stationary industrial machinery including conveyors, some types of mills, injection moulding machinery, stamping presses and lifts. 

In the most simple terms, a hydraulic pump works by forcing a liquid through a piece of machinery to create movement. It converts mechanical power into hydraulic energy. (Hydraulic energy is the combination of flow and pressure that occurs when a liquid is forced through a confined space). This transmission of force drives the motion of pieces of the machine.

But exactly how does a hydraulic pump work? While there are many types of hydraulic pumps, the general principle is a two-part process. First, a mechanism moves to create a vacuum at the pump inlet, which forces liquid from the reservoir into the pump. Second, another action moves this liquid to the pump outlet and into the hydraulic system.


Different Types of Hydraulic Pumps


While there are different types, the answer to the question ‘how does a hydraulic pump work’ is generally the same. The difference is in the details. First, hydraulic pumps fall into two basic types – fixed displacement and variable displacement. In a fixed displacement pump, a fixed amount of liquid is moved with each rotation. Changing the pump’s speed is the only way to increase or decrease the pump’s displacement. Variable displacement pumps are a bit more complicated.  The key difference is that the operator can change the amount of fluid being displaced per cycle while a variable displacement pump is running.

That is only one way of classifying hydraulic pumps. Many different types of pumps are found in many different applications. Gear pumps are a type of fixed displacement pump. Many specific types of pumps can be designed to be either fixed or variable displacement. Rotary vane pumps and pistons pumps, for example, can be either fixed or variable.

Whatever the application, the real question is how does a hydraulic pump work most efficiently… and the answer is ‘with a quality seal correctly installed.’ Whatever type of hydraulic pump you depend on, that pump depends on a seal made of a material appropriate to the application and fitted correctly. Pump seals should be inspected regularly and replaced when they show signs of wear to ensure the machinery functions at optimal effectiveness and efficiency. If you need advice or are in doubt on what is right for your application, contact one of our experts today to see all solutions Abbey Seals has to offer.