As we all know, hydraulic motors are essential components in the hydraulic system. They are always used to provide high torque at low speed and have a wide range of applications to satisfy your various project requirements. But you may not know how hydraulic motors work and we will explain hydraulic motor symbols and its working principle to you, then you will better operate your hydraulic motors.
What’s the Hydraulic Motor Symbol?
Hydraulic motor symbols are internationally accepted engineering languages, which can easily and directly indicate hydraulic motors’ location, function, type and connection relationship in a hydraulic system. On one hand, hydraulic motor symbols can be the basis for your analysis of hydraulic system failures and do not rely on text language. On the other hand, they help visualize complex hydraulic systems and guide hydraulic system installation and component procurement.
Basic Graphics Composition on Hydraulic Motor Symbols
Hydraulic motor symbols are composed of some graphics and each has a different meaning.
They typically consist of a dark triangle pointing inwards, a circle, and a line with a triangular arrow.
Outermost circles are basic components of hydraulic motor symbols and they represent rotary devices. The inner triangle is the most critical element, which represents energy conversion and flow. A solid black fill indicates it is a hydraulic device that operates with hydraulic fluid.
In addition, if a bidirectional dark triangle appears in a hydraulic motor symbol, it means this hydraulic motor can rotate in both directions. And triangular arrows indicate hydraulic motors are designed to operate in both directions.
Various Types of Hydraulic Motor Symbols
Fixed Displacement Symbol
Fixed displacement symbols typically consist of a dark triangle pointing inwards, a circle, and a line with a triangular arrowhead. And these symbols mean that fluid discharged volume is fixed after one revolution of your hydraulic pump. Their output flow rate depends on drive shafts’ speed only.
Fixed displacement symbol includes 2 types: unidirectional fixed displacement symbol and bidirectional fixed displacement symbol.
Unidirectional Fixed Displacement Symbol
Unidirectional fixed displacement symbol represents a hydraulic motor with simple structure, low cost and has wide applications. This hydraulic motor can convert hydraulic energy into unidirectional rotational mechanical energy. Its displacement is fixed, and this output speed is proportional to motors’ input flow. In addition, this hydraulic motor’s rotation direction needs to be controlled by an external oil circuit and is unidirectional.
Bidirectional Fixed Displacement Symbol
This symbol represents that your hydraulic motors can rotate in both directions, and hydraulic motors’ fluid inlet and outlet can be interchanged easily through changing fluid circuit direction. Hydraulic motors’ displacement is also fixed. This type of hydraulic motor is very suitable for mixing equipment, winches or other equipment with repeated forward and reverse cycles.
Variable Displacement Symbol
Variable displacement symbols have the same components as fixed displacement symbols, and they have a double-headed arrow line passing through this triangle. These symbols mean that fluid discharged volume can be adjusted after one revolution of your hydraulic pumps. Even if hydraulic motors’ drive shafts speed remains unchanged, the output flow rate can also be changed.
Unidirectional Variable Displacement Symbol
This hydraulic motor symbol shows that your hydraulic motors’ displacement can be adjusted according to your specific needs. For example, if you increase displacement, the speed will decrease and hydraulic motors’ output torque will increase. You need to remember that this symbol generally refers to a type of hydraulic piston motor: variable piston motor.
Bidirectional Variable Displacement Symbol
Bidirectional variable displacement symbol features hydraulic motors with extremely flexible functions for advanced control. This type of hydraulic motors can achieve bidirectional rotation and displacement can also be changed. This hydraulic motor has various applications such as drive systems of engineering equipment or ship propulsion.
Rotary Actuator Symbol
Rotary actuator symbol is composed of a semi-circle, solid triangles, and curved arrows pointing inward. This type of hydraulic motor can only rotate through a limited angle like 90°, 180°, 270° instead of continuous rotation. Moreover, this symbol indicates your hydraulic motors can also rotate both clockwise and counterclockwise. This symbol is usually used on vane swing hydraulic motors.
Working Principle of Hydraulic Motors
The working principle of hydraulic motors is easy for you to understand, hydraulic motors always convert hydraulic fluid energy into mechanical energy and generate rotary motion.
After hydraulic fluid with high pressure is added to your hydraulic motor, it will strike internal core moving parts such as gears, vanes, or pistons. And then due to fluid’s incompressibility,
huge fluid pressure drives these internal components to produce rotational motion.
In addition, if hydraulic systems’ pressure difference is high, the torque generated by your hydraulic motor will increase. And its output speed will also improve through increasing hydraulic motor input flow.
Below are some common types of hydraulic motors and we will introduce specific working principles about them in combination with their internal components.
1. Hydraulic Gear Motor
Hydraulic gear motor consists of a driving gear and a driven gear. After hydraulic fluid enters your sealed hydraulic housing and gradually fills gears’ meshing clearance, high-pressure fluid drives two gears to rotate and generate strong torque. During operation, fluid moves to the low-pressure side and leaves your hydraulic motor through outlets, which can help your hydraulic motor continuously output rotational power.
2. Hydraulic Vane Motor
With a rotor with vanes, pressurized hydraulic fluid acts directly on vanes and produces unbalanced thrust, which can drive the rotor to rotate. When vanes and rotor rotate, a closed cavity is formed in your hydraulic vane motor. Then hydraulic fluid flows from high-pressure areas to low-pressure areas and returns to the hydraulic tank. In this way, your hydraulic vane motors can repeatedly convert hydraulic energy into rotational mechanical energy.
3. Hydraulic Piston Motor
Hydraulic piston motors have a cylinder block with pistons and these pistons are pushed into motion by pressurized hydraulic fluid. And motors’ output shafts also rotate because they are connected with cylinder blocks. As cylinder blocks rotate, pistons will be pressed back by swash plates when they rotate to fluid return areas and then discharge fluid.
4. Orbital Hydraulic Motor
Star-shaped inner rotors and stators with matching teeth are core components in orbital hydraulic motors and they will form several closed cavities. And high pressure fluid will flow into each closed cavity in sequence as they rotate. This special internal design makes it large in displacement and high in output torque.
Conclusion
Understanding hydraulic motor symbols and working principles not only helps you maintain your hydraulic motors, but also helps you accurately select a hydraulic motor that suits your project to achieve efficient engineering tasks. If you have any other requirements about hydraulic motors, Target all can offer professional and practical solutions and meet your various application needs.
FAQ
1. Do radial and axial piston hydraulic motors work on the same principle?
Yes, they basically work with the same principle, and their rotation is generated by pressurized hydraulic fluid driving their pistons. However they have different pistons’ direction. Pistons of axial piston hydraulic motors are arranged parallel to their output shaft axis and they are suitable for high speed conditions.
Pistons of radial piston hydraulic motors are arranged radially perpendicular to their output shaft axis. In addition, these radial layouts allow them to accommodate more pistons and have larger force-bearing areas, which help have larger displacement and output torque. But their speed is relatively low.
2. How to distinguish hydraulic motors and hydraulic pumps by symbols？
You can distinguish between hydraulic pumps and hydraulic motors directly by inner triangles’ direction in the symbol. If the symbol shows solid triangles pointing inside the circle, it means it is a hydraulic motor. And if solid triangles in the symbol point outside the circle, it represents a hydraulic pump.
