Using two pulleys and a belt is an efficient way to transfer mechanical power in an enclosed space. The engine of an automobile often includes a pulley system located on the side of the motor. The misalignment of a pulley system can cause strain on the shafts and bearings and can also result in stretching of the belt. The use of simple tools can ensure misalignment doesn't occur during the instillation of a pulley system or during maintenance.
Remove the belt from the pulleys.
Level the motor and the machine the motor will drive by using a level and shims.
Establish a datum line. Suspend a plumb bob from the end of the shaft from the pulley that will be driven so that the bob hovers right above the floor. Place a mark on the floor directly under the bob. Repeat this for the other side of the pulley and draw a straight line between the two marks. This is the datum line and represents the axis of the driven pulley.
Suspend the plum bob from the center of the driven pulley. Place a mark on the ground and use a square to draw a line perpendicular to the datum line.
Suspend the plumb bob from the center of the motor's pulley. Align the motor so the plum bob hovers over the center line extending from the driven pulley. Draw a perpendicular line underneath the motor's pulley using a square. Align the motor's pulley using the plumb bob and the perpendicular line as references.
Reinstall the belt, leaving 1/8 inch of sag for every foot of belt.
