MOTORS, DRIVES & CONTROLS
E
ngineers 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? Here, we explain how to navigate through what can sometimes 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 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 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.
COSTLY MISTAKES There are a number of commonly made mistakes that result in the wrong have serious consequences both for the
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The best
CHOICE
David Proud explores a smooth path to drive coupling selection
coupling and the other elements in the drivetrain. Often, it does not take long before these issues rise to the attention of maintenance engineers in the form of a catastrophic failure of the coupling and hours of unplanned downtime. Other bearings, shafts and gears, which will ultimately impact motors or gearboxes.
must fully evaluate and understand the forces and loads that will be applied to the coupling in use. Making an ‘educated guess’ is not an option and could result in either a coupling being or design overkill, which would result in an unnecessarily larger and more expensive solution to the application.
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
for the task. Generally, couplings with a higher torque rating will be larger and axial, radial or angular misalignment that the coupling will be required to and it is essential that the coupling to be used, is able to meet these criteria but have the capacity to accommodate a service without failing. Another contributing factor that
where there are minimal shock or reversing loads, keyways and taper bushes will be a reliable solution. For applications where there may be high shock loads it may be preferable to avoid a keyway solution and instead opt for shrunk discs, which will also provide backlash-free operation. From a maintenance perspective, the time required to remove or replace a
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