T–61
SECTION 15 HANDLING AND STORAGE
The following has been condensed from RMA Bulletin No. IP-3-4: "Storage of Power
Transmission Belts":
Recommendations for proper belt storage is of interest to designers as well as to users.
Under favorable storage conditions, high-quality belts maintain their performance capabilities and
manufactured dimensions. Good storage conditions and practices will result in the best value from
belt products.
Power transmission belts should ideally be stored in a cool and dry environment. Excess
weight against belts resulting in distortion should be avoided. Avoid storing belts in environments
that may allow exposure to sunlight, moisture, excessive heat, ozone, or where evaporating solvents
or other chemicals are present. Belts have been found to be capable of withstanding storage,
without changing significantly, for as long as 8 years at temperatures less than 85° F (30° C) and
relative humidity below 70 percent without direct contact with sunlight.
Proper handling of synchronous belts is also important in preventing damage that could
reduce their performance capabilities. Synchronous belts should never be crimped or tightly bent.
Belts should not be bent tighter than the minimum recommended pulley size specified for each belt
section, or pitch. Belt backside bending should be limited to the values specified in Table 21 for a
minimum diameter backside idler.
SECTION 16 STANDARDS APPLICABLE TO BELTS
Different belt tooth configurations are shown in Figure 19 and their characteristics are described
in Table 3, both on page T-15. Since synchronous belts are manufactured by several manufacturers,
each has established individual standards. Subsequently, the following general standards have
been published:
1. Specifications by the Rubber Manufacturers Association for Drives using Synchronous
Belts.
2. Synchronous Belt Drives – specification by the International Organization for Standardization.
Based on these, as well as standards developed by belt manufacturers, the following information
is presented in this handbook:
Recommended Tension for Length Measurement ........................................ Table 22
Belt Width Tolerances ....................................................................................Table 23
Pitch Length Tolerances ................................................................................ Table 24
Center Distance Tolerances .......................................................................... Table 25
Overall Belt Thickness dimensions ................................................................ Table 26
Overall Belt Thickness Tolerances ................................................................ Table 27
Length Measurement
The pitch length of a synchronous belt is determined
by placing the belt on a measuring fixture comprising
two pulleys of equal diameter, applying tension and
measuring the center distance between the two pulleys.
One of the pulleys is fixed in position, while the other is
movable along a graduated scale.
The fixture is shown schematically in Figure 33.
Any pair of equal-diameter pulleys of the proper pitch
and manufactured to specifications may be used for
measuring. The measuring tension is given in Table 22.
Fig. 33 Length Measuring Fixture
NB =
Number of
Teeth of Belt
Np =
Number of Grooves
of Pulley
Center
Distance
Total
Measuring
Force
