Motor Mount

A fixed-position adjustable base lets the motor be pushed or pulled into position, so the belt can be installed and adjusted. After the belt is pulled over the pulley and before the mounting bolts are tightened, one or more adjusting screws force the motor away from the driven pulley until the desired tension is reached.

A dual positioning base such as the one in figure above has two adjusting screws located directly under the motor feet. This style comes in configurations identical to single-adjustable bases, as well as in reinforced construction to extend the application range to about 200 hp. The major difference in the two styles is that dual screws provide a simple and positive way to hold alignment.

As belt tension is applied, the motor drive end is pulled away from the driven unit. The mounting nuts are not tightened until tension adjustment is complete. The misaligned condition shown in the figure should not occur if the screws are adjusted correctly. By alternating turns between the two screws, alignment is maintained at the same time tension is adjusted. With the single screw, you must pry and hold the motor in an aligned plane as the mounting bolts are tightened. Depending on motor size, the alignment tool can be as simple as a screwdriver or pry bar. To hold a larger motor in place you may need a hoist or Come-Along.

Many standard fixed-position bases have mounting studs that protrude from slots. You must lift the motor over the studs during installation and loosen the nuts to make tension adjustments. A caution: Never loosen the mounting nuts more than absolutely necessary to let the motor be moved during tension adjustment. If they are too loose, the motor can pivot and lift toward the driven pulley during belt tightening. Then, when the nuts are tightened, belt tension will be higher than required and you may overstress the mounting studs.