DRIVES, MOTORS & GEARS
ENSURING RELIABLE OPERATION
REICH DRIVE SYSTEMS
A SMOOTH PATH TO DRIVE COUPLING SELECTION
Engineers and designers working on power
transmission applications can often face a
daunting task when it comes to specifying
the most appropriate drive coupling for the
task in hand. Detailed consideration must
be given to both sides of the drive equation,
input and output, with regard to torque,
shock loads, starting frequency, temperature
and environmental conditions, but where
to begin.
In this informative article, David Proud
General Manager of Reich Drive Systems UK
explains how to navigate through what can
sometimes be seen as a technical minefield
for designers and engineers.
Drive couplings vary greatly in their design
and capabilities, so for any given application
engineers must ensure that they specify the
drive coupling correctly to ensure reliable
efficient, and in the more challenging
applications, safe operation.
A detailed review of what the coupling
will be subjected to in use is an essential
starting point. Factors such as torque
transmission, speed ranges, running start
/ stops and potential shock loadings
are just some of the key elements in the
selection of the coupling. However, we
must also consider alignment between the
various components, the environmental
operating conditions that could include
high temperatures or moisture etc., and any
maintenance requirements or restrictions.
There may also be potential limitations on
available space, size and / or weight, which
will have to be taken into account. The
prime mover, diesel or gas engine, hydraulic
or electric motor will also be influential in
the specification and selection of the drive
coupling.
Get it right, and the coupling will provide
years of uninterrupted service, requiring
little or no maintenance in its own right,
whilst ensuring that mating components are
protected from undue stresses and keeping
downtime to a minimum.
COMMON MISTAKES CAN BE
COSTLY
There are a number of commonly made
mistakes, which result in the wrong coupling
being specified. This can have serious
consequences both for the coupling and the
other elements in the drive train. Often, it
does not take long before these issues rise
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PECM Issue 35
to the attention of maintenance engineers
in the form of a catastrophic failure of the
coupling and hours of unplanned downtime.
Other less visible effects will be undue wear
on bearings, shafts and gears, which will
ultimately impact motors or gearboxes. For applications where there may be high
shock loads it may be preferable to avoid
a keyway solution and instead opt for a
taper bush fixing, or couplings with shrunk
discs, which will also provide backlash free
operation.
Before making a final decision on selecting
the drive coupling the specifier must fully
evaluate and understand the forces and
loads that will be applied to the coupling
in use. Making an “educated guess” at these
values is not an option and could result in
either a coupling being specified which is
not fully up to the job, or design overkill,
which would result in an unnecessarily
larger and more expensive solution to the
application. From a maintenance perspective, the time
required to remove or replace a coupling or
any change parts, is a major consideration.
Therefore, the selection of a coupling
which not only meets all of the technical
and application requirements, but is either
maintenance free, or has the ability to
have change parts replaced in-situ will
bring significant benefits to uptimes and
efficiency.
The specific application will dictate whether
the coupling required is a disc coupling,
shaft to shaft coupling, auxiliary coupling
or other variant, however it is essential
that consideration is given to factors such
as the torque rating and torsional stiffness
required for the task. Generally, couplings
with a higher torque rating will be larger
and less flexible. In addition, the degree of
axial, radial or angular misalignment that
the coupling will be required to compensate
for will influence choice, and it is essential
that the coupling to be used, is able to
meet these criteria, but have the capacity
to accommodate a level of unexpected
deflection whilst in service without failing.
Another contributing factor, which will
influence success, is how the coupling is
mounted. In applications where there are
minimal shock or reversing loads, keyways
and taper bushes will be a reliable solution.
If there is any doubt on the part of the
individual responsible for specifying and
selecting the coupling, seeking expert
advice from the manufacturer will both
eliminate risks and ensure longevity and
reliability in operation. With a history
spanning over 70 years, Reich Kupplungen
has built up unrivalled expertise in the
design and manufacture of drive couplings
for use across a wide range of industries
and applications. The company also
embraces a D2C (design to customer)
principle, which allows the creation
of customised high-quality and long-
lasting power transmission products in
collaboration with the customer and their
specific requirements.
Telephone +44(0) 161 714 4191
Website - www.reich-uk.com