Most coupled machines are oriented horizontally. However, there are some applications of vertically-oriented machines, such as water intake pumps, tank mixers, etc. In these cases, proper alignment of shaft centerlines is still important.
The main difference between horizontal and vertical alignment is that vertically-oriented machines normally do not have “feet”, as in the case with standard motors. They are mounted to the stationary machine using a C-face adaptor. The C-face adaptor bolts to the top of the stationary machine. It uses a grooved machined surface, and threaded holes (usually four or more). A C-face motor has a mating machined surface on its shaft side, and a hole pattern which matches the hole pattern in the adaptor. Bolts are used to attach the motor to the driven machine, and the mating machined surfaces serve to align the shaft of the motor to the driven machine.
Even though these mating machined surfaces serve to align the two machines together, there are instances where misalignment can occur:
- If machining errors are present in the manufacturing process;
- If damage occurs on the machined surface, usually due to mishandling;
- If dirt, grit, slag, paint, or other foreign material is between these surfaces.
Some laser shaft alignment tools can be successfully used to detect and correct misalignment of vertically oriented machines. The bolts are used as orientation areas, since inclinometers are of no value in this particular application. The bolt circle and number of bolts in it become the surfaces where shimming occurs.
Measurements are taken of the misalignment between the shafts, using the bolt locations as the points of reference. The laser alignment tool can then calculate the shim amounts required at each bolt location.
Normally, very little offset parallel misalignment is detected. Most of the misalignment is axial. By adding differing thicknesses of shims in the bolt locations, angular misalignment is corrected.
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