By Zak Khan
When engineers are selecting couplings for heavy and percussive loads, there are a few design considerations to keep in mind. These include the type of coupling, the operating conditions and the spacing of the various couplings and shafts.
When considering the ends of couplings, the end that carries the load or otherwise interacts with the system is of primary concern. In heavy and percussive loading situations, make sure that this end is rigid enough to stand up to the rigors of operation. If, however, the system has requirements for flexibility or movement, a bearing that is rigid in one direction but flexible in another, such as a bellows coupling, may be more suitable.
When it comes to ball and roller bearings, roller bearings can support heavier loads than a comparable ball bearing. This means that ball bearings are usually found in light loading applications, while roller bearings find use in more demanding situations. Bearings that use cages usually support less than those that have a full set of rollers.
Keep in mind the direction the load as well. Thrust ball bearings only accommodate for axial loads in one direction. Angular contact thrust ball bearings are good for normal axial loads that occur at high speed. Heavier loads that are purely axial allow the use of needle roller thrust bearings, cylindrical bearings and tapered roller bearings. Spherical roller bearings are for axial loads in one direction only, as well as radial loads. For heavy, alternating loads, try using two cylindrical rollers or two spherical rollers mounted together.
Heavy, combined loads require unique combinations and types of bearings. These situations are often specialized and consulting with bearing manufacturers is helpful. Keep in mind additional support bearings that only handle certain kinds of loads, such as axial or radial, may also be required in addition to the necessary load carrying bearings.
Also, remember that heat, moisture and lubrication affect how well bearings and couplings accommodate loads. Reading the documentation provided by manufacturers is vital to make sure that the system is not placing bearings and couplings in unacceptable operating conditions. Proper maintenance and lubrication should always occur.