A fundamental aspect of mechanical drives is the axial transmission of torque from a driving machine to a driven machine. A typical example is a motor connected to a pump. This is achieved by joining the shafts of each machine through a device called the coupling. A key requirement of any coupling is the alignment of the shafts.

The topic Shaft alignment and couplings introduces those aspects and presents couplings and shaft alignment methods suitable for various operating conditions. For couplings, the emphasis is put on selection, assembly and disassembly, while the portion that deals with shaft alignment methods demonstrates proper handling of the tools to take valid measurements and ensure a proper alignment. An add-on named Laser alignment of shafts is optionally available.