Capital Equipment News June 2015

CAPITAL EQUIPMENT NEWS

JUNE 2015

onstant flow turbo coupling has been

designed for vehicles in order to help

eliminate the shock effects that the

drivetrain may experience throughout day-

to-day operation. This, in turn, reduces

wear and tear dramatically, thus decreas-

ing maintenance costs. Turbo couplings are

of the utmost importance in the commercial

vehicle market, partially due to the sheer

size and weight of the vehicles, and par-

tially due (at least in South Africa) to the

dubious nature of the drivers.

But how exactly can a component eliminate

shock effects so easily? Simply put, the torque

transfer system is designed so that there is no

solid and mechanical contact. Usually through

the use of a mineral oil, turbo couplings make

use of a liquid torque-transfer system in order

to give the vehicle its drive. Voith Turbo is the

worldwide leader when it comes to these hy-

drodynamic couplings, and an analysis of their

system reveals exactly how it works.

While the system as a whole is easier to un-

derstand with a diagram, the system can be

explained as two wheels that are not connect-

ed or touching in any way, but are encased to-

gether and form part of a closed system. On the

sides of the wheels that face each other there

are hollowed out slats, and in these slats rests

the coupling’s liquid. The first wheel, known as

the pump wheel, is driven by the motor. This

starts spinning and the torque transmitted by

the engine is converted into the kinetic ener-

gy of the liquid. This liquid, essentially thrown

into the slats of the second wheel, known as

the turbine wheel, starts it spinning and in so

doing, converts the kinetic energy of the liquid

back into mechanical energy and provides the

vehicle with drive.

Of course, at a standstill the liquid is at rest,

and at start-up the pump wheel and the tur-

bine wheel are turning at different speeds

until what is called nominal operation is

achieved. This means that the two wheels are

turning at almost the same speed (the minor

difference in speed being called the nominal

slip), but what is important to note here is that

the liquid transfer between the two wheels

ceases. The flow becomes stationary and the

liquid, for all intensive purposes, becomes a

solid component in the drivetrain, this means

that only the torque required by the driven

machine is transmitted.

Voith have paid special attention to the min-

ing industry in recent years and have now

developed a water-operated turbo coupling.

The water-operated coupling could be used in

any application; however, it was designed with

a specific view to end-users in the mining in-

dustry. The industry’s vast demands on output,

safety and environmental protection have re-

stricted much of the old technology used; how-

ever, Voith have turned this into an opportunity

for innovation.

Water as an operating medium for the turbo

coupling holds significant improvement over

the use mineral oil. Most notably, it is far more

readily available, and it is environmentally

friendly. On top of this, also take into account

that it is often the case that vehicles at min-

ing sites will be operating underground. It is

undoubtedly safer to use water in such cir-

cumstances.

“The water coupling transmits power smoothly

and virtually wear-free, without any mechan-

ical contact between the torque-transmitting

components,” Voith advertise. This innovative

coupling is not only important to the vehicles

that are involved in mining operations though.

These couplings can run any numbers of belt

conveyers, fans and pumps that may be on site

as well. It is evident that, among others, the

mining industry is set to receive huge benefit

thanks to this innovation from Voith Turbo.

THE ADVANTAGES

of turbo coupling

By Pierre Sanson