Hydraulic systems have countless applications from the breaks in a car, to construction equipment and manufacturing technology. They are simple and cost-efficient mechanisms that are used to create movement, lift heavy loads or repeat a particular action.
How do hydraulic systems work?
The basic idea of all hydraulic systems is that force applied at one point is transmitted through a fluid to another point. In order for this to work, the fluid (which is usually oil) must be incompressible, meaning its volume should not change when pressure is applied.
Piping and cylinders within the system can be structured and altered in many different ways to achieve specific results. The initial force applied can be multiplied in the process, allowing for applications such as the lifting of heavy loads. This is because piping within the system can be any length or shape, and it can fork so that one applied force can drive several cylinders.
Essential components of a hydraulic system
The complexity of a hydraulic system depends on its specific use, however all hydraulic systems have the same basic components.
- Reservoir oil tank
- Hydraulic pump
- Power source
As an overview, hydraulic fluid is pumped from the reservoir into the rest of the system, creating hydraulic power. The pressurised fluid then passes through valves and flows to the actuator where hydraulic power is converted to mechanical energy to achieve the desired function.
Below we will go through each of the components and describe their function within the overall system.
1. Reservoir Oil Tank
The reservoir holds the incompressible fluid, which is usually hydraulic oil. It also protects the fluid from getting contaminated, which is critical to ensure the hydraulic system functions optimally.
Piping is simply, but importantly, the hollow structures that carry the hydraulic fluid from one location to another within the system.
3. Hydraulic Pump
The role of hydraulic pumps is to force the hydraulic fluid from the reservoir to the rest of the circuit.
Firstly, the pump creates a vacuum at the pump inlet which forces the fluid from the reservoir into the pump. Next, the pump pushes the fluid to the pump outlet and then forces it into the rest of the hydraulic system.
The different types of hydraulic pumps are:
Fixed displacement pumps
These pumps have an unchangeable flow rate, so every stroke moves the same amount of fluid. They are good for jobs with a single action that are repeated for long periods. Examples include gear, gerotor and screw pumps.
Variable displacement pumps
These pumps can change the flow rate of the fluid and outlet pressure. They can power a variety of complex equipment, but they are more expensive and require more attention than fixed displacement pumps. Examples include piston pumps and vane pumps.
Hand or manual hydraulic pumps
These pumps are operated manually by the hand and foot.
4. Power source
An electric motor or other power source is required to make the mechanical elements of the pump work.
5. Hydraulic Actuator
A hydraulic actuator is the component which changes the hydraulic power in the fluid into mechanical power to achieve the desired action.
The actuator can be a:
- Hydraulic cylinder which creates linear movement (movement in a straight line).
- Hydraulic motor which creates torque (a twisting force) and rotation.
Valves control the pressure, flow rate and direction of the fluid moving through the circuit. There are many types of valves with specific functions. We will outline the most common below.
Pressure control valves
Pressure control valves limit the pressure within the system to protect all the components from damage.
One type is the pressure relief valve. It is normally closed, but opens when system pressure exceeds a maximum value. It will then direct the fluid back to the reservoir to keep the system’s pressure below the maximum level.
Another type, called the pressure reducing valve, stops flow to a particular area of the system until the pressure is below the maximum level.
A sequence valve makes sure a certain level of pressure is reached in one section of the system before another is activated.
To prevent losing control over a load, a counterbalance valve is used to create a backpressure in the return line.
Flow control valves
As the name suggests, flow control valves influence the rate at which the fluid flows throughout the system. This is achieved by decreasing or increasing the diameter of the opening the hydraulic fluid flows through.
Flow control valves are used to affect how fast the movement produced by the actuator is.
Direction control valves
Direction control valves can stop, start and change the direction of the flow of hydraulic fluid.
The simplest of these valves is called a check valve and it allows the hydraulic fluid to flow in one direction, while blocking fluid flow in the other direction.
Direction control valves can vary in the number of ports they have and the number of flow paths they allow. A spool type valves, controls the direction of flow, but is not limited to one direction.
Filters prevent the hydraulic system from being contaminated. This is essential to ensure the system works effectively and safely. Without a filter, a hydraulic system’s components may wear down quickly and pipes may get blocked.
A suction line filter stops any contaminants in the reservoir fluid getting into the rest of the hydraulic system. It is located at the input side of the hydraulic pump.
A return line filter cleans out any contamination in the hydraulic fluid at the end of the return line.
Equipment, servicing and maintenance for hydraulic systems
Whether you are needing to buy high-quality hydraulic system equipment, or are looking for maintenance and repair services, we can help.
At Hydraulic Solutions and Sales, we have an extensive range of Australia’s highest quality hydraulic products . Our dedicated, expert team is well equipped to install and repair all types of hydraulic systems.
Why not give us a call on +61 8 9437 5388, or fill out our contact form, to see what we can do for you?