Rail traction systems have undergone a change from the traditional use
of DC motors to the use of more compact AC systems. These motors are
lighter, require less maintenance, operate at higher speeds and provide
braking to stopping conditions; however they also carry the penalty of
greater torque “ripples” and generate higher shock torques.
These conditions require that the couplings between the AC motor and
gearbox or between the drive shaft and track wheel be designed with
higher excitation torques, speeds and shock loadings, and fit in a reduced
space with the ability to absorb greater movements and misalignments.
Each train car typically has two wheel trucks (bogies in Europe), which are
modular chassis sub-assemblies that house the wheels, axles, drives and
MEETING THE NEED FOR TORSIONAL FLEXIBILITY
For more than 45 years, Twiflex has been recognized by rail
traction OEMs worldwide for their superior coupling technologies. Twiflex
Layrub couplings are specifically designed to meet the requirements of
modern traction systems. The Layrub coupling is based on a standard
rubber component which can be configured and adapted into housings for
varying light rail, metro, commuter and regional train bogie applications.
Layrub couplings feature enhanced torsional flexibility and
damping. The coupling’s sophisticated sub-assembly
is capable of handling relatively large angular and axial
misalignments. The Layrub profile produces uniform stress
and deflection throughout the cross section of the rubber
The standard block material is natural rubber available in
4 duro hardness levels. Neoprene material is also available for
high temperature applications, where additional damping
is required, or where the presence of mineral oil creates a
The low torsional stiffness of Layrub couplings limits
high transmitted torque peaks while improving damping
properties. The couplings are immune to water
contamination and require no maintenance. Reversing
loads is not a problem since Layrub couplings have zero
Every bogie design is unique as traction engineers
continually strive to develop solutions that are more
lightweight and compact.
Layrub couplings are available in a range of configurations
including close-coupled, telescopic or fixed shafts, and
combined with CV joints to meet the wide range of
individual bogie design specifications.
PROVEN PERFORMANCE WORLDWIDE
Layrub couplings have a proven record of toughness,
reliability and long service in climates and track conditions
ranging from the Arctic wastes of Northern Scandinavia to
the arid conditions of the Australian outback.
Twiflex has successfully supplied couplings for various rail
car programs including British Railways, Swedish State
Railways, Stockholm Metro, Helsinki Metro, Rotterdam
Metro and Trams, Queensland Railways, Melbourne Trams,
Gothenburg, Waggonfabrik and Istanbul Trams, Toronto
Subway, Indian Railways, and Baltimore Mass Transit.