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Coupling Assembly and Maintenance – Part 1


Companies of all sizes and national or international reach which use industrial machinery will usually afford a good amount of time and money ensuring their machines are up to spec before sending them into action. One huge part of this process is making sure that the shaft couplings are properly aligned, as well as ensuring they are assembled correctly and that regular maintenance is scheduled to keep on top of any problems that might arise.


Couplings should last a good while before needing to be replaced, but only when they are assembled and aligned correctly and they receive regular maintenance. Without regular maintenance, the coupling could fail as soon as the machine approaches full power.


Maintenance Starts with the Correct Coupling Design


Industrial machinery uses a wide variety of different kinds of coupling, though most often it will be some kind of flexible coupling design.  Even these flexible couplings require regular maintenance, and that begins with the original assembly of the machine’s components. Many types of coupling may fit a particular shaft, but that doesn’t necessarily mean that it is the correct coupling for that machine.


The purpose of a coupling is to transmit power from one shaft to the other, while also serving as the weak link in the chain so that the coupling fails before any damage can be inflicted upon the shafts and the machine itself. There are also several other factors to consider when selecting the right coupling for the job at hand, such as their ratings for torque, horsepower and starting load. As it is imperative that you use the correct coupling for your machine, liaise with your engineering department and check with the couplings manufacturer or your company’s coupling suppliers to ensure you are using the right coupling design.


Proper Assembly Makes Maintenance Easier


Maintaining your couplings will be a lot easier if you follow the couplings manufacturer’s guidelines on the usage of the particular coupling you are using, as well as adhering to the engineering department and/or machine designer’s recommendations.  Do make sure you understand the different types of couplings as their type will determine how they fit onto the shaft. Some couplings are ‘slip fit’, while others might be ‘interference fit’. This is a particularly important distinction as the hub of a ‘slip fit’ coupling should slightly larger than the shaft, while the hub of an ‘interference fit’ coupling should be slightly smaller.


Never use a coupling that is too loose on the shaft as this will cause damage to the shaft as well as overloading the key. A loose coupling fitting will vibrate more than the shaft or the machine fed by the shaft is built to endure and thus you will experience far more wear and tear than is necessary.


Also never use a coupling that fits on to the shaft too tightly because at worst it will break the coupling hub, or at the very least it will result in poor axial spacing, which we will discuss in further detail in Part 2 of this blog.


If you require flexible couplings or are interested in a particular couplings manufacturer, then contact YB Components who are the leading coupling suppliers and can ship these parts all over the world.