Hydraulic motors are a common component in a larger hydraulic system. Hydraulic motors convert hydraulic energy into mechanical energy. In industrial hydraulic systems, pumps and motors are typically used in conjunction with proper valves and piping to form a hydraulic powered transmission. Usually, a pump is connected via a carrier line to a motor, which then draws fluid from a reservoir and forces it into the motor. The fluid forces the movable components of the motor into motion, which in turn rotates the attached shaft. The shaft, which is mechanically linked to the work load, provides rotary mechanical motion. Finally, the fluid is discharged at low pressure and transferred back to the pump.
Most hydraulic motors are fixed-displacement motors. Displacement is a motor rating refering to the amount of flow that is required for a specified drive speed. Variable-displacement piston motors are also utilized, but mostly in hydrostatic drives. Other important ratings of a motor are torque and pressure. These ratings indicate how much load a hydraulic motor is capable of handling. Hydraulic motors are entirely enclosed and self-contained. These characteristics allow them to be submerged or operated in many hostile environments.
Most hydraulic motors are fixed-displacement motors. Displacement is a motor rating refering to the amount of flow that is required for a specified drive speed. Variable-displacement piston motors are also utilized, but mostly in hydrostatic drives. Other important ratings of a motor are torque and pressure. These ratings indicate how much load a hydraulic motor is capable of handling. Hydraulic motors are entirely enclosed and self-contained. These characteristics allow them to be submerged or operated in many hostile environments.
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Last Updated: Sep 2009
Last Updated: Sep 2009
What are Hydraulic Motors?
Three types of hydraulic motors are gear, vane and piston-type motors. Each of these types can be either unidirectional or reversible, although most motors used in mobile equipment are the latter. In hydraulic gear motors, one of the two driven gears is attached to the output shaft. Gear motors, which are the least expensive but the noisiest of the hydraulic motors, have the ability to operate at high speeds; however, they are inefficient at low speeds. In a hydraulically balanced vane motor, the vane on the inlet port side of the motor is subject to full system pressure, while the chamber leading the vane is subject to the much lower outlet pressure, forcing oil through the motor and, as a result, developing torque. Hydraulic vane motors are the most popular general-purpose motor, but they are limited by their tolerance to high pressure systems and the higher percentage of slippage or internal leakage relative to the lower total fluid flow at low speeds. Hydraulic piston pumps can be either axial or radial and are generally the most expensive of the hydraulic motors. They have advantages over the other motors, however, in that piston motors are far more adaptable to high torque, low speed operation and higher system pressure applications.
Hydraulic motors provide solutions in applications involving infinite speed control, stalling under full torque, high power-to-weight ratio and small size. Their characteristics make them useful in a wide variety of industries. The aerospace industry uses hydraulic motors to actuate wing flaps. The food processing industry uses them to power automated manufacturing machinery. Hydraulic motors are also used in trenchers, construction equipment, waste management and recycling, forestry, agriculture, dredging and industrial processing. Other applications for hydraulic motors include drives for marine winches, submersible ROV's, conveyor and auger systems and mining equipment.
Hydraulic motors provide solutions in applications involving infinite speed control, stalling under full torque, high power-to-weight ratio and small size. Their characteristics make them useful in a wide variety of industries. The aerospace industry uses hydraulic motors to actuate wing flaps. The food processing industry uses them to power automated manufacturing machinery. Hydraulic motors are also used in trenchers, construction equipment, waste management and recycling, forestry, agriculture, dredging and industrial processing. Other applications for hydraulic motors include drives for marine winches, submersible ROV's, conveyor and auger systems and mining equipment.
1. Drive shaft - via electric motor, hydraulic motor, belt and pulley etc.
2. Roller bearings - rigid support, immersed in lubricating oil bath.
3. Fixed-angle cam - translates rotary motion into linear to the hydraulic cells.
4. Hydraulic cells - displace diaphragms via pressurised oil.
5. Diaphragms - hydraulically balanced, no stress during flexing.
6. Inlet valve assemblies - simple design, allow liquid into pump chamber.
7. Outlet valve assemblies - allow liquid to flow into pressure discharge line.
2. Roller bearings - rigid support, immersed in lubricating oil bath.
3. Fixed-angle cam - translates rotary motion into linear to the hydraulic cells.
4. Hydraulic cells - displace diaphragms via pressurised oil.
5. Diaphragms - hydraulically balanced, no stress during flexing.
6. Inlet valve assemblies - simple design, allow liquid into pump chamber.
7. Outlet valve assemblies - allow liquid to flow into pressure discharge line.
8. Pressure regulating valve - controls outlet pressure and prevents pump overload.
