Hydraulic Motor

A hydraulic motor transforms hydraulic energy into rotary mechanical energy applied to a resisting object by means of a shaft connected with the motor. They closely resemble hydraulic pumps in construction and size. The difference being, instead of pushing the fluid as the pump does, in a hydraulic motor the rotating elements (i.e. vanes, gears, pistons, etc.) are pushed by the oil pressure to enable the motor shaft to rotate and thus develop the necessary turning torque and continuous rotating motion.

Types of Motors:

Hydraulic motors are classified as:
1.Uni-directional, or
2.Bi-directional.

As per their construction, hydraulic motors are of:

Gear type

This is generally a fixed capacity imbalanced motor. The hydraulic imbalance in a gear motor is caused by gear teeth unmeshing. Meaning all teeth subjected to system pressure are hydraulically balanced except for one side of one tooth on one gear. This is the point where the torque is developed. The larger the gear tooth or higher the pressure, more is the torque produced. Check out more on Hydraulic Gear Motor.

Vane type

This is a positive displacement motor that develops an output torque at its shaft by allowing hydraulic pressure to act in the vanes that are extended. The vane motor includes: vanes, rotor, cam-ring, shaft and port plates. In vane motors the imbalance is caused by the difference in vane area exposed to hydraulic energy which is due to the eccentric position of the rotor to the housing. When pressure oil enters the inlet port, the unequal area of the vanes results in development of a torque in the motor shaft. The larger the exposed area of the vane, or higher the pressure, more is the torque that is developed. This makes the shaft rotate.

Piston type

In general three types of piston motors exist. These include: These are positive displacement motors that can develop an output torque at the shaft by allowing oil pressure to act on the pistons. The piston type motors include: in-line piston, axial piston and radial piston. The axial piston motors are used for medium to high pressure and moderately high power ranges whereas, radial piston motors are used for very high pressure ranges.

Rating of Hydraulic Motors

The hydraulic motors are also rated in various ways like as the displacement of the motor, which can be fixed or variable. Displacement is the volume of the hydraulic fluid that is required to turn the shaft of the motor. It is this displacement which provides the mechanical power of the motor and it is measured inches cubed or centimeters cubed. The higher the displacement the more liquid that is needed and at the same time more power is generated. In case of fixed displacement motors, they have the same torque at all motor speeds. In a variable displacement motor, different speeds and torques are allowed which lets the motor to adjust output based on the load on the system.

Hydraulic motors also have pressure rating. This is the highest pressure that the motor can be operated at. If used in systems with more pressure than the rating there is every chance of leaking within the motor and and the motor can be damaged. Having the right pressure rating is necessary. To go higher is good but going lower is risky.

Related Article

How Does Hydraulic Motors Work?

Send ONLINE ENQUIRY for bulk purchase of hydraulic motors