Types of Hydraulic Systems Used in Machines


Machines are an integral part of our daily lives, and they have made our lives easier in countless ways. From simple tools like scissors to advanced construction equipment, machines come in different sizes and shapes and have a wide range of applications. However, what allows these machines to function with such precision and power is the hydraulic system. A hydraulic system uses pressurized fluid to generate, control and transmit power, making it an essential component in many machines. In this article, we will explore the different types of hydraulic systems used in machines and their practical applications.

1. Open-Center Hydraulic System
The open-center hydraulic system is the most commonly used type of hydraulic system. It involves a pump, valves, and actuators placed in an open circuit, allowing the fluid to flow continuously. The hydraulic pump draws oil from the reservoir and sends it to the control valve, which then directs it to the actuator and back to the reservoir. This type of system is ideal for machines that require a high flow rate, such as excavators, forklifts, and loaders.

2. Closed-Center Hydraulic System
A closed-center hydraulic system differs from an open-center system in that it has a closed-loop circuit. Instead of the fluid returning to the reservoir, it is continuously pumped through the system, providing constant pressure and allowing precise control over the machine’s movements. This type of system is commonly used in heavy-duty machines, such as cranes, power presses, and drilling rigs, where precision and control are crucial.

3. Load-Sensing Hydraulic System
The load-sensing hydraulic system is a variation of the closed-center system, with an added feature that allows it to adjust its pressure and flow according to the load required. This makes it a highly efficient and energy-saving system as it only provides the necessary pressure and flow, reducing unnecessary wear and tear of the components. Load-sensing systems are commonly used in modern construction equipment, such as bulldozers, excavators, and cranes.

4. Pressure-Compensated Hydraulic System
A pressure-compensated hydraulic system is similar to a load-sensing system, but instead of adjusting the flow rate, it adjusts the pump’s displacement to maintain a constant pressure. This is achieved through a control valve that senses the pressure of the fluid and adjusts the pump accordingly. This type of system is commonly used in machines with fluctuating load demands, such as hydraulic presses, bending machines, and injection molding machines.

5. Hydrostatic Hydraulic System
The hydrostatic hydraulic system is based on the principle of fluid statics, where the pressure of the fluid increases as it flows through a restriction. This system uses a motor and a pump to create a high-pressure stream of fluid, which is then used to drive a motor or cylinder. Hydrostatic systems are commonly used in machines that require high power, such as heavy-duty excavators, cranes, and bulldozers.

In conclusion, hydraulic systems play a crucial role in the functioning of various machines. From the simple open-center system to the complex hydrostatic system, each type offers unique advantages in terms of flow rate, control, and efficiency. These systems are highly specialized and are designed to meet the specific requirements of the machine they are used in. So the next time you use a machine, remember the hydraulic system that drives it and appreciate its precision and power.