Product Manual

Output Speed and Torque: These are the key criteria for matching a
gear reducer to the application needs.
Center Distance: The basic measurement or size reference for worm
gear reducers. Generally, the larger the center distance, the greater the
reducer capacity. Center distance is measured from the centerline of the
input shaft to the centerline of the output shaft.
Horsepower: A reducer’s input horsepower rating represents the
maximum prime mover size the reducer is designed to handle. Output
horsepower, while usually listed by reducer manufacturers, has little
application relevance. Speed and torque are the real considerations.
Overhung Load: This is a force applied at right angles to a shaft
beyond the shaft’s outermost bearing. Too much overhung load can cause
bearing or shaft failure. Unless otherwise stated, a reducer manufacturer’s
overhung load maximums are rated with no shaft attachments such as
sheaves or sprockets. The American Gear Manufacturers Association pro-
vides factors, commonly called “K” factors, for various shaft attachments
by which the manufacturer’s maximum should be reduced. Overhung
load can be eased by locating a sheave or sprocket as close to the reducer
bearing as possible. In cases of extreme overhung load, an additional
outboard bearing may be required.
The following formula can be used to calculate overhung load (OHL):
OHL (pounds) =
Torque (inch-pounds) x K (load factor constant of overhung load)
R (radius of pulley, sprocket or gear)
where, K equals 1.00 for chain and sprocket, 1.25 for a gear, and 1.5 for
a pulley and v-belt.
Thrust Load: This is a force applied parallel to a shaft’s axis. Mixers,
fans and blowers are among driven machines that can induce thrust
loads. Exceeding manufacturers’ maximums for thrust loading can cause
premature shaft and bearing failure.
Mechanical and Thermal Ratings: Mechanical ratings refer to the
maximum power a reducer can transmit based on the strength of its
components. Many industrial reducers, including LEESON’s, provide
a 200% safety margin over this rating for start-ups and momentary
overloads. Thermal rating refers to the power a reducer can transmit
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