Product Manual

-31-
Motor Guidelines for Belted Applications
The information contained in this document is intended to be used
for applications where LEESON Electric and Lincoln Motors motors are
connected to other equipment through the use of a V-belt drive. These
are to be used as guidelines only since LEESON Electric and Lincoln
Motors does not warrant the complete drive system.
The goal of any belted system is to efficiently transmit the required
torque while minimizing the loads on the bearings and shafts of the
motor and driven equipment. This can be accomplished by following
these four basic guidelines:
1. Use the largest practical sheave diameter.
2. Use the fewest number of belts possible.
3. Keep sheaves as close as possible to support bearings.
4. Tension the belts to the lowest tension that will still transmit the
required torque without slipping.
1. Sheave Diameter Guidelines
In general, smaller sheaves produce greater shaft stress and shaft
deflection due to increased belt tension. See Table 1 for minimum
recommended sheave diameters. Using larger sheaves increases the
contact with belts which reduces the number of belts required. It also
increases the belt speed, resulting in higher system efficiencies. When
selecting sheaves, do not exceed the manufacturer’s recommended
maximum rim speed. Typically 6,500 feet per minute for cast iron
sheaves, 8,000 feet per minute for ductile iron and 10,000 feet per
minute for steel. The following formula will determine sheave rim speed:
Shaft RPM x 3.14 x Sheave Dia. in inches
12
2. Number of Belts
In general, use the fewest number of belts that will transmit the required
torque without slipping. See Table 1 for maximum recommended
number of belts. Each belt adds to the tension in the system which
increases load on the shafts and bearings. Belts are most efficient when
operated at or near their rated horsepower.
If the sheaves have more grooves than the number of belts required, use
the grooves closest to the motor.