GANDHINAGAR INSTITUTE OF TECHNOLOGY

Fluid Power Engineering Topic:~”Hydraulic Machines”

(Fluid coupling, Fluid torque converter)

MECHANICAL DIPARTMENT B_2

Prepared By: Kushal Panchal

FLUID COUPLING

Introduction When we want to transfer the rotation energy or

torque of one shaft to another, we have to connect those two shafts with such a arrangements which can transfer the power with maximum efficiency and as per need.

In above kind of situations, ”The couplings” is used.

The coupling is device which connects the driving and driven shaft and also transfer the power.

Fluid Coupling A Fluid coupling is used for transmitting power or

torque from one to another shaft with the help of oil (fluid).

Without MECHANICAL connection of two shafts.

Construction.. It consist of two rotating

elements as a radial pump impeller and radial flow turbine runner.

The pump impeller is mounted on driving shaft and turbine runner is mounted on a driven shaft. Both the impeller and runner are identical in shape and they are enclosed in single housing filled with oil.

There is no direct contact between the shafts.

How it works…

Working When the driving shaft with pump impeller is rotated,

the oil starts moving from the inner radius to outer radius of the pump impeller by centrifugal action.

Due to centrifugal action and the speed of impeller, the pressure and kinetic energy of oil at outer radius increases. The oil then enters the turbine runner at the outer radios of the runner and flows inwardly to the inner radios of the runner. It will exert force and make it run.

The magnitude of the torque increases with an increases in the speed of driving shaft.

And cycle will continue.

Efficiency In actual prectice, the speed of driven shaft is

always less then the driving shaft by 2% to 4% due to friction and turbulence loss in the impeller and runner passage, which is known as SLIP.

The efficiency of the power transmitted by fluid coupling is about 98%.

In fluid coupling the driven shaft is free from engine vibrations.

Need… … … Industrial Rail transportation

Fluid couplings are found in some Diesel locomotives as part of the power transmission system. Self-Changing Gears made semi-automatic transmissions for British Rail.

Automotivesemi-automatic transmissions and automatic transmissions.

Since the late 1940s. Aviation

The most prominent use of fluid couplings in aeronautical applications was in the DB 601, DB 603 and DB 605 engines where it was used as a barometrically controlled hydraulic clutch for the centrifugal compressor and the Wright turbo-compound reciprocating engine

FLUID TORQUE CONVERTOR

Intoduction The fluid torque convertor is used for transmitting

variable (increased or decreased) torque from one shaft to another shaft.

A fluid torque convertor is nothing but a improved FLUID COUPLING.

The different torque( +/-) is achieved by adding third member (reaction member) between pump impeller and turbine runner.

The construction

How it works When oil flowing from the pump impeller to turbine

Runner exerts the torque on the stationary guide vanes which change the direction of oil. As result of this, the oil reacts upon the turbine runner and reduces the speed of turbine runner.

As we know, P NT. Hence, if the T at the driven shaft is to be increased, the

corresponding value of the speed at the same shaft should be decreased.

The speed of driven shaft is decreased by decreasing the velocity of oil, which is flow from pump impeller to the turbine runner and then through the STATOR which change the direction of oil, therefore the convergent is possible.

Application Automatic transmissions on automobiles, such as

cars, buses, and on/off highway trucks. Forwarders and other heavy duty vehicles. Marine propulsion systems. Industrial power transmission such as conveyor

drives, almost all modern forklifts, winches, drilling rigs, construction equipment, and railway locomotives.

Thank you for your precious T I M E… !!!