Hydrostatic drive system

Hydrostatic drives

In this type of drives a hydro-static motor and a pump is used. The engine drives the pump and it generates a hydro-static pressure on the fluid. The pressurised fluid then feed to the motor and motor drives the wheel. In this transmission, mechanical power is generated in the motor because of displacement under hydraulic pressure. The fluid also carries kinetic energy but since it leaves the motor at the same velocity as that at which it enters, there is no change in its kinetic energy content and kinetic energy plays no part in the transmission of power.

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Principle of hydrostatic drive system

It consists of a pump which converts torque and rotation of mechanical shaft in to flow of pressurized fluid combined with a hydraulic motor, which converts fluid under pressure into rotating torque on the output shaft.

Pump and motor are identical in construction, but they may vary in size and displacement, particularly when torque multiplication is needed. By employing variable delivery of hydraulic unit, it is possible to obtain wide range of output ratios.

Advantages of hydrostatic drives

1. Hydro-static drives eliminate the need for mechanical transmission components like clutch and gear box as well as allied controls.

2.  It provides for smooth and precise control of vehicle speed and travel.

3. This system ensures faster acceleration and deceleration of vehicle.

4. It offers better flexibility in vehicle installation because of wide range in choice of pumps and motors of different capacities and of fixed or variable displacement type. Hydraulic fluid pipelines replace mechanical drive line components. 

Applications of hydrostatic drives

1.   It is used to move the machine tools accurately.

2.   It is used in steering gears of ship.

3.   It is used in warships to operate gun turrets.

4.   It is used in road rollers, tractors and earth movers, and heavy duty trucks.