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Keyways aren’t the only way to couple heavy-duty motor and gearbox shafts. In fact, keyways aren’t even the best way when you consider the alignment and installation difficulties you’ll encounter when installing keyed shaft couplings that may weigh thousands of pounds. A better alternative is to use couplings that employ a mechanical shrink fit around the shafts.

Keyed shaft connections are common, but they have their shortcomings. In reciprocating applications, keyways tend to concentrate stresses around the key – leading to wear and possible failure. Fortunately, you have two alternatives that offer an even distribution of locking forces.

Shrink discs are external locking devices that provide a high capacity interference fit as well as all positive features of a conventional connection method, but which are much easier and faster to assemble and dismount. When a torque is transmitted through the connection of a shaft and a hollow shaft, the contemporary solution is to use a shrink disc instead of a failure-prone keyed connection. Shrink discs are typically available with inner diameters from 14 mm up to 500 mm.