Hydrodynamic Torque Converter Type EL - Voith Turbo


Hydrodynamic Torque Converter Type EL - Voith Turbo

Hydrodynamic Torque Converter Type EL

Operating principle

Torque converters are hydrodynamic

transmissions, based on the

”Foettinger Principle“. The heart of

Voith‘s hydrodynamic torque converter

is it‘s hydraulic circuit; consisting

of pump, turbine and guide

wheel with adjustable guide vanes.

The mechanical energy of the motor

is converted into kinetic fl uid energy

through the pump wheel. In the turbine

wheel, this kinetic energy is

converted back into mechanical

energy and transmitted to the output

shaft. The adjustable guide vanes

regulate the mass fl ow and thereby

providing variable output speed.

Customer benefi ts

■ robust design with long service


■ low investment cost

■ easy maintenance

■ easy to install and to control

■ wide operating range and

accurate speed control

■ wear free power transmission

■ fast response time

■ damping of torsional vibrations

and shock loads

■ suitable for a wide variety of

environmental conditions, i.e.

applications in tropical climate,

the desert or low temperature

zones, as well as in hazardous


■ high reliability and availability

■ unloaded motor start

■ overload protection of motor

■ no harmonic vibration problems

■ excellent torsional vibration


■ increased output torque for startup

or emergency conditions

Design and Applications


The EL type torque converter is a

fully self supported unit. The rotating

parts are supported in the closed, oil

tight housing. Main motor and driven

machine are connected to the torque

converter via connecting couplings.

The oil tank is integrated into the

cast iron housing, the oil pump is

Controls and guide vane


driven by the input shaft, providing

the working and lube oil. The shafts

are supported in anti-friction bearings.

Guide vanes Pump wheel Turbine wheel

The adjustable guide vanes can be

controlled by a pneumatic, hydraulic

or electric actuator, which receives

an input signal of 4 – 20 mA or

0.2 – 1 bar from the customer‘s

master control system. The feedback

signal, to incorporate the

torque converter in a closed control

loop, can be provided by switches or

as a 4 – 20 mA signal.

Guide vanes closed (L x = 0%) Guide vanes max. opened (L x = 100%)

Input Torque / Speed Characteristics

L x = 100%

L x = 75%

L x = 50%

L x = 25%

L x = 0%


The torque converters of this series

are variable-speed drives, especially

developed for electric motors with

constant speed (squirrel cage or induction

motors) or diesel engines

with limited regulating range. With

the adjustable guide vanes, speed

and torque can be controlled within

a wide operating range. The unload-

Output Torque / Speed Characteristics

L x = Guide vane setting

T P = Input torque

T T = Output torque

n P = Input speed

n T = Output speed

1 Torque converter

2 Shaft driven gear pump

3 Pressure relief valve

4 Heat exchanger

5 Oil fi lter

6 Orifi ce

ed motor start allows a smooth and

controlled start of the driven machine.

These torque converters are

mainly used on constant torque applications

e.g. displacer machines,

working against a constant pressure

at low and high speed settings, like

reciprocating pumps, screw pumps

or compressors as well as agitators,

Simplifi ed longitudinal section of torque converter

1 7 5 3 2 4


P & I Diagram Power chart



1 Input shaft

2 Pump wheel

3 Turbine wheel

4 Output shaft

5 Adjustable guide vanes

Converter input power P 1 [kW]










mixers, extruders or winches. The

hydrodynamic principle of the torque

converter provides a natural overload

protection of the motor and the

driven machine by dampening

torque spikes, which increase the

lifetime of the entire drive train.

6 Guide vane adjustment


7 Gear pump

8 Pressure relief valve

9 Oil reservoir

EL 10

EL 9

EL 8

EL 7

EL 6

EL 5

EL 4

EL 3


700 1000 1500 2000 2500 3000

Converter input speed n1 [rpm]


ø75 h6

Voith Turbo GmbH & Co. KG

Variable Speed Drives

Voithstr. 1

74564 Crailsheim, Germany

Tel. +49 7951 32 -261

Fax +49 7951 32 -650




Torque converter type EL 7 / 8 Torque converter type EL 9 / 10




ø75 h6

max. 970



ø95 h6



150 ø95 h6

max. 1015



Cr 208 en 06.2006 1.000 aik / WF. Technical data and illustrations subject to change.

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