Variable-Speed Multi-Disk Coupling
Type MDC
Voith Variable-Speed Multi-Disk Coupling:
light weight, space-saving, economical
1
2
3
4
Input shaft
Control oil
Scoop tube
Rotary piston
5
6
7
8
Outer disk carrier
Inner disk carrier
Output shaft
Working oil
2
2
3
4
1
4
5
3
6
1
8
7
7
6
5
New coupling concept
Voith Turbo has complied with the requirements of
the market for a drive solution for high-power and
low-speed driven machines.
Based on their know-how and many years of experience on the sector of hydrodynamic variable-speed
couplings, Voith Turbo has developed the variablespeed multi-disk coupling, a drive component completing the product line as economical variant of the
proven Voith variable-speed coupling.
This coupling type is designed, in particular, for lowspeed driven machines. For this application, the use
of a standard hydrodynamic variable-speed coupling
is not always the optimal solution for reasons of
space.
2
Due to its design characteristics and physical properties, the new variable-speed multi-disk coupling
offers essential advantages for the above-mentioned
applications:
■ compact design
■ space-saving
■ low capital costs
■ high efficiency
■ synchronization at 95% speed, elimination of slip
losses
■ robust design
■ long lifetime
■ increase of economic efficiency by using speed
control for the driven machine
Design and Function
0% scoop tube position, thus small oil ring
and low axial force. Motor can run up to
speed at no-load.
An oil ring and therefore axial force is built
up by positioning the scoop tube. Gentle
acceleration of driven machine. Stepless
speed variation with increasing or decreasing axial force. The force imposed on the
disk package increases until synchronization of disks at approx. 95% speed.
100% scoop tube position. Disks are
synchronized. Slip losses eliminated.
Start-up
Partial load operation
Nominal operation
Function
Oil supply
The torque to be transmitted is regulated by varying
the disk package contact pressure. This pressure
varies together with the radial height of the oil ring
(control oil) formed in an annular chamber rotating
with input speed.
Oil supply is provided by a mechanically driven
pump and an electric motor driven auxiliary lube oil
pump, also providing oil for external lubrication of
motor and driven machine. Working oil flows through
the disk package from the inside to the outside and
a heat exchanger is used for re-cooling.
The height of the oil ring varies by means of a tilting
scoop tube. The centrifugal force produces a rotational pressure resulting in an axial force acting on
the disk package. The stronger the axial force, the
higher the torque transmitted.
At 95% speed the disks are synchronized resulting
in pure mechanical power transmission, thus eliminating the slip losses.
Integration in the process-controlled circuit
By controlling the scoop tube via an actuator, the
variable-speed multi-disk coupling can be integrated
in a speed or process-controlled circuit.
3
Technical data
Selection chart
6.0
5.5
5.0
4.5
4.0
10
3.2
2.8
72
92
7
Power [MW]
2.4
2.0
77
5
1.6
1.4
63
1.2
1.0
0.9
0.8
200
0
52
300
400
600
800
4
1,000 1,200 1,500
Speed [rpm]
4
Power ratings
Dimensions / weights
The design of the variable-speed multi-disk coupling
is essentially determined by the input speed and
power of the driven machine. The selection chart
shows the power transmitted as a function of output
speed for the various multi-disk coupling sizes.
The adjoining table shows the main dimensions and
weights of the individual coupling sizes.
MDC Horizontal
MDC Vertical
a
øo
b
øn
e
f
m
c
s
q
øg
f
d
Oil reservoir
q
h
i
ør
j
øp
= Space required for attaching parts
MDC Horizontal
Size
a
b
c
524
630
775
927
1072
1,260
1,420
1,725
2,180
2,400
930
1,200
1,260
1,620
1,880
560
600
710
850
1,000
d
560
500
520
470
470
e
700
800
1,000
1,200
1,380
f
øg
210
210
250
350
350
100
120
150
190
220
h
i
j
Oil reservoir
[l]
Weight
[kg]
600
880
920
1,200
1,400
600
800
850
1,000
1,150
570
720
750
930
1,080
400
550
800
1,100
1,400
1,100
2,000
3,600
7,500
9,800
MDC Vertical
Size
524
630
775
927
1072
m
øn
øo
øp
q
ør
s
Weight [kg]
1,260
1,420
1,725
2,180
2,400
840
1,120
1,240
1,480
1,700
1,080
1,400
1,610
1,920
2,200
1,080
1,400
1,610
1,920
2,200
210
210
250
350
350
100
120
150
190
220
1,230
1,420
1,740
2,130
2,400
1,500
2,500
4,500
9,000
12,000
Dimensions in mm, weights without oil filling
5
Applications
Marine drives
Another application for the variable-speed multi-disk
coupling are diesel engine driven marine drives by
interaction of parabolic ship propeller curve with the
diesel engine characteristic. An extended regulation
range of the propeller speed results from the use of
the variable-speed multi-disk coupling since a down
regulation from no-load speed downward is possible.
The variable-speed multi-disk coupling is synchronized above the no-load speed of diesel engine.
Thus slip losses do no longer occur.
Advantages and functional alternatives
■ Creep speed
■ Manoeuvering against pollard pull curve
■ Overload protection for engine and propeller
6
Arrangement scheme of a main marine drive with
variable-speed multi-disk coupling.
Vertical installation of a variable-speed
multi-disk coupling in a cooling water
pump drive.
Industrial applications
Retrofit
The multi-disk coupling is used on machines with
parabolic torque curve, especially low-speed
machines with high power ratings. On account of
the compact and space-saving design, the coupling is most suitable for vertical installation.
On account of its small size and low weight, the
variable-speed multi-disk coupling is also suitable for subsequent installation in existing units.
It is not necessary to replace the existing motor.
Industrial applications
■ Circulating pumps
■ Cooling water pumps
■ I.D. fans
■ F.D. fans
■ Vertical pumps
7
cr 270 en, 08.2008, aik / WA, 1.000. Dimensions and illustrations without obligation. Subject to modifications.
Voith Turbo GmbH & Co. KG
Variable-Speed Drives
Voithstr. 1
74564 Crailsheim, Germany
Tel. +49-7951 32-0
Fax +49-7951 32-650
vs.drives@voith.com
www.voithturbo.com / variable-speed