Building Tips – Aligning Drive Motors

Roy C. speaks to this challenge.

I prefer to drive my prop shafts using a belt. I like toothed belts but others have had good experience using O rings. Belt drives have the advantages that they eliminate couplings, can have a speed ratio other than 1:1, allow variations in motor positioning, and simplify alignment. I typically mount my motors ahead of, and in line with, the prop shafts, as shown in the picture. If it were necessary, the motors could be mounted above the shaft, or off to the side. A 1:2 speed ratio, for example, provides better low speed control.

Even when I have the motors straight in line with the shaft and use a coupling, I use shims to set the vertical alignment of the motors. When I am glueing the mounting block for a motor into the hull, I leave a gap of, say, 1/8″ under the motor mounting bracket. So when I come to adjust the tension on the drive belt, I adjust the shim thickness to get the tension correct. 

The picture shows the motors and belt drives in my “Empress of Canada” model. You can see several thicknesses of shim under the motor.