Hydraulics: Concept, Structure, and Basic Operating Principles

Hydraulics is a vital technology, widely used in modern life. From industrial machinery like dock levelers to vehicles, this system plays an indispensable role.

In the article below, we will explore hydraulic systems in a simple and easy-to-understand way. You will learn about the concept, structure, and operating principles. Whether you are an engineer or just curious about technology, Naltako’s article will provide you with a comprehensive overview of hydraulics.

What is Hydraulics?

Hydraulics is a branch of science and engineering that studies the movement and energy transmission of fluids (hydraulic oil, lubricant, etc.) within a closed system. When a fluid is compressed, it creates pressure, which in turn generates force to perform work.

Hydraulic systems are widely applied in many industrial fields such as production, machinery manufacturing, aviation, shipbuilding, automotive assembly, mining, heavy industry, and even in advanced robotics.

Structure of a Hydraulic System

Hydraulic Cylinder: A linear actuator that converts hydraulic energy into mechanical motion in a straight line. It consists of a cylinder barrel, cylinder head, piston, piston rod, seals, and oil guiding components.

Hydraulic Motor: Similar to a hydraulic cylinder but creates rotary motion. Hydraulic motors provide energy for rotating parts such as conveyor belts, wheels, etc.

Hydraulic Pump: Plays a central role in the system, converting mechanical energy into hydraulic energy. The pump sucks oil from the reservoir and pushes it into the system under high pressure.

Pressure Regulator: Maintains stable pressure in the system by adjusting the oil flow through the valve.

Directional Control Valve: Controls the flow direction of hydraulic oil, determining the movement direction of the actuator. This valve has 3 positions:

• 1-Off: Stops the flow, no movement.
• 2-Forward: Oil flows into the actuator, pushing it forward.
• 3-Return: Oil flows out of the actuator, pulling it back to the original position.

Actuator: Converts hydraulic energy into mechanical motion. In this diagram, the actuator is a hydraulic cylinder, creating linear motion.

Load: The object or resistance force that the actuator must act upon.

Oil Tank: Stores hydraulic oil when the system is not operating and supplies oil to the pump when needed.

See more: Hydraulic Lifting Equipment Safety Handbook

Basic Technical Specifications of Hydraulics

In hydraulics, there are two basic parameters (quantities) that play a vital role in determining the performance and working capacity of the system:

Flow rate: The volume of hydraulic oil transported by the pump per unit of time. Flow rate directly affects the movement speed of actuators like cylinders or hydraulic motors. The higher the flow rate, the faster the movement. Common units are liters per minute (l/min) or cubic centimeters per revolution (cc/rev).

Pressure: The force exerted on a unit area of the fluid. In a hydraulic system, pressure is created by the pump and acts on the actuators to generate force and motion. The higher the pressure, the greater the force produced. Common units are bar, megapascal (MPa), or pounds per square inch (psi).

Operating Principle of a Hydraulic System

The operating principle of a hydraulic system is based on converting mechanical energy into hydraulic energy, then transmitting and amplifying force through a fluid (hydraulic oil).

Advantages and Disadvantages of Hydraulic Control Systems

Advantages

• Hydraulics can generate large forces and torques, suitable for heavy industrial applications like hydraulic lift tables.
• Velocity, direction, and force can be easily and precisely adjusted.
• Hydraulic systems are often more compact than other drive systems of the same power.
• High starting torque helps the system easily overcome initial inertia.
• Less vibration and noise, especially at high speeds.
• Relief valves help prevent overload, protecting the system.
• System pressure can be continuously monitored via gauges and sensors.
• Easy to integrate with automated control systems.

Disadvantages

• Friction in pipes and other components can reduce system efficiency.
• Air bubbles in hydraulic oil can cause noise, reduce efficiency, and damage components.
• Changes in oil temperature can affect viscosity and system performance.
• Oil leaks cause environmental pollution and fire hazards if not handled promptly.
• Initial investment costs for hydraulic systems are often higher than other solutions like pneumatics.

Applications of Hydraulics in Daily Life

Industry

• Construction machinery: Excavators, bulldozers, cranes, drilling rigs, pile drivers, etc.
• Lifting equipment: Hydraulic cargo lifts, personnel lifts, loading docks, pallet jacks…
• Manufacturing machinery: Plastic injection molding machines, metal stamping machines, CNC cutters, etc.
• Automation systems: Industrial robots, production lines, etc.

Transportation

• Automobiles: Braking systems, power steering, suspension systems, etc.
• Aircraft: Flight control systems, landing gear, braking, etc.
• Ships: Steering systems, anchoring, etc.

Agriculture

• Tractors: Lifting and control systems, etc.
• Combine harvesters: Control systems, etc.

Other Fields

• Medical: Dental chairs, operating tables, etc.
• Military: Tanks, fighter jets, etc.

Thanks to its flexibility, ability to transmit large forces, and high precision, hydraulics has become an indispensable part of many fields, contributing to increased productivity and work efficiency.

You may be interested in: Building a professional inventory management system in logistics

Hydraulic System Maintenance and Repair

Hydraulic system maintenance plays a crucial role in ensuring the performance and lifespan of industrial machinery. In the past, maintenance often only occurred when a failure happened. However, with the development of technology and modern production scales, periodic and preventive maintenance is necessary to minimize downtime and repair costs.

Common causes of hydraulic system failure:

• Oil filter is contaminated or clogged
• Oil leakage through seals
• Lack of oil in the reservoir
• Loose pipe joints causing air cavitation in the pump
• Using inappropriate hydraulic oil
• Excessive oil pressure
• Excessive oil temperature

To prevent the above issues, a comprehensive preventive maintenance program is required, including:

• Selecting high-quality components suitable for operating requirements.
• Ensuring tight joints, correct torque, and thorough system flushing before use.
• Regularly checking critical parts such as filters, oil sight glasses, pressure gauges, and temperature sensors.
• Sampling and testing oil quality to detect early signs of abnormalities.
• Ensuring operating and maintenance staff are fully trained to recognize and handle potential incidents.
• Storing information on incidents, corrective measures, and maintenance history to analyze and improve system performance.

In addition to maintenance, environmental issues related to hydraulic systems should be noted, including:

• Using environmentally friendly bio-hydraulic oil.
• Properly storing and disposing of waste oil.
• Minimizing noise and oil leakage.

Conclusion

Through this article, Naltako hopes you have gained a better understanding of hydraulics, from basic concepts to practical applications. This is not only useful knowledge but can also help you make the right decisions in work and life.

If you need advice on hydraulic solutions for your business, do not hesitate to contact us.