Rockwell Automation 1325L DC Motors, Frames C210ATZ - C440ATZ - Manual (Page 11)

DC Motors 11
Minimum V-Belt Sheave Diameters
Application of Pulleys, Sheaves, Sprockets and Gears on Motor Shafts
To avoid excessive bearing loads and shaft stresses, belts should not
be tightened more than necessary to transmit the rated torque. The
pre-tensioning of the V-belt drive should be based on the total
tightening force required to transmit the horsepower divided by the
number of belts. This procedure avoids the excessive load caused by
tightening individual belts to a prescribed level recommended by belt
manufacturers.
Mounting
In general, the closer pulleys, sheaves, sprockets or gears are mounted
to the bearing on the motor shaft, the less will be the load on the
bearing. This will give greater assurance of trouble-free service.
The center point of the belt, or system of V-belts, must not be beyond
the end of the motor shaft.
The inner edge of the sheave or pulley rim should not be closer to the
bearing than the shoulder on the shaft but should be as close to this
point as possible.
The outer edge of a chain sprocket or gear must not extend beyond
the end of the standard motor shaft.
Minimum Pitch Diameter for Drives Other Than V-Belt
To obtain the minimum pitch diameters for flat belt, timing-belt,
chain and gear drives, apply the multiplier given in
Table D to the
minimum sheave diameter calculated for V-belt drives.
Shaft Extension and Method of Drive
Frames C210ATZ-C250ATZ are supplied with a shaft and bearing
system suitable for either coupled or belted drives. Frames C280ATZ-
C440ATZ are supplied with larger shafts and roller bearings when
belted drives are specified.
Table D
Multipliers for Drives other than V-belt
1 The above multiplier is intended for use with conventional single-ply flat, belts. When other than single-
ply flat belts are used, the use of a larger multiplier is recommended.
2 It is often necessary to install belts with a snug fit. However, tension should be no more than necessary
to avoid belt slap or tooth jumping.
Drive Multiplier
Flat Belt (See Note 1) 1.33
Timing Belt (See Note 2) 0.9
Chain Sprocket 0.7
Spur Gear 0.75
Helical Gear 0.85