Center Distance and Belt Length

The relationship between center distance and belt pitch length is given by the following formula:

where:

Lp = pitch length of belt, inches
C = center distance, inches
D = pitch diameter of large pulley, inches
d = pitch diameter of small pulley, inches
ø = sin–1 (D-d/2C), degrees

The approximate center distance can be found by this formula:

where: K = 4L – 6.28 (D+d)

The exact center distance can then be determined by trial, using the belt pitch length formula, or use center distance tables available from belt manufacturers.

You can also use our online tool

Center Distance Calculator

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The pitch length increment of a synchronous belt is equal to some multiple of the pitch of the belt. For example, the belt length increment of XL section (0.200 pitch) must be 0.200, 0.400, 0.600, etc.

Table 18 Torque rating for MXL section (0.080 inch pitch)
BELT WIDTH (INCHES) RATED TORQUE (IBF-INCH) FOR SMALL PULLEY
10MXL 0.255 12MXL 0.306 14MXL 0.357 16MXL 0.407 18MXL 0.458 20MXL 0.509 22MXL 0.560 24MXL 0.611 28MXL 0.713 30MXL 0.764
0.12 0.29 0.35 0.40 0.46 0.52 0.57 0.63 0.69 0.81 0.86
0.19 0.48 0.58 0.67 0.77 0.86 0.96 1.05 1.15 1.34 1.44
0.25 0.67 0.80 0.94 1.07 1.20 1.34 1.47 1.61 1.87 2.01