As its name suggests, a small hydraulic motor is really just a scaled down version of the more standard hydraulic motor. While smaller motors cannot provide the same amount of power as larger motors, small hydraulic motors weigh much less and can be used in small scale applications.
Like most other hydraulic motors, these motors utilize pressurized fluid to generate torque and rotational motion. The pressurized fluid, usually oil, is stored in a reservoir until the motor is needed. When the motor is operating, the oil is released from the reservoir and flows into the motor itself. Hydraulic motors can come in many configurations, like gear, vane, radial piston, gerotor, and axial plunger motor configurations.
When the pressurized fluid enters the motor, it presses against the internal components of the motor (the gears, pistons, cylinders, etc.), which move or turn to rotate a shaft. Thus, the hydraulic motor converts the hydraulic energy of the fluid into mechanical energy in the form of rotational motion and torque. Once the fluid exits the motor, it is recycled and pressurized in the reservoir.
Although they retain all of the capabilities of larger hydraulic motors, small hydraulic motors are typically used in applications requiring high precision, such as in military operations or robotics. Regardless of the size of a hydraulic motor, there are certain considerations that must always be thought through while building and before using one.
Proper fluids must always be used and checked for compatibility with the metal material of the motor. All of the relief valves should be checked as well as the pump and fluid reservoirs. Such precautions will ensure that a hydraulic motor will function at its optimum level for the longest period of time.