I used easylaser e420 to do the alignment of cooling tower motor/gearbox.
The e420 consists of a display, M (movable unit) and S (stationary unit).
M should be placed on the shaft of the movable item (i.e the unit that you are going to do the modifications on for the vertical and horizontal alignment) and S on the shaft of stationary unit.
In our case, the motor or the gearbox could be assumed as M unit, because both could be adjusted and shims could be placed below any of the two. I started considering the motor as the movable unit, however, I found that the motor level is higher than the gearbox level and I had no choice to take it down because the motor was placed directly on the steel base without shims.
So I have to consider the gearbox as tge movable part and I applied the necessary shims to get the required alignment.
The alignment was done considering a tolerance of 0.07 mm because the motor rpm is 1450. In case motor rpm is greater than 2900 or 3650, the accepted tolerance should be 0.05 mm.
First vertical alignment shiuld be applied by adding/removing shims, then horizontal alignemt will follow by adjusting the side bolts.