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DESIGN
ASSISTANCE
SYNCHRONOUS BELTS
Size Designations. Synchronous Belt sizes are identified by a standard number. The first digits specify the belt length to one-tenth inch followed by the belt section (pitch) designation. The digits following the belt section designation represent the nominal belt width times 100. For example, an L section belt 30.000 inches pitch length and 0.75 inches in width would be specified as a 300L075 Synchronous Belt. The nomenclature for double-sided belts will be the same as for single-sided belts with the addition of the prefix "D" in front of the belt section. Example 300DL075.
Standard Sections. Belt sections are specified in terms of "pitch". Table below gives the Standard Belt Sections and their corresponding "pitch".
| STANDARD BELT SECTION - INCHES | |||
| Belt Section | Pitch | h s | h d |
| Single-Sided | |||
| MXL | 0.080 | 0.045 | |
| XL | 0.200 | 0.090 | |
| L | 0.375 | 0.14 | |
| H | 0.500 | 0.16 | |
| XH | 0.875 | 0.44 | |
| XXH | 1.250 | 0.62 | |
| Double-Sided | |||
| DXL | 0.200 | 0.120 | |
| DL | 0.375 | 0.180 | |
| DH | 0.500 | 0.234 | |
Nominal Tooth Dimensions. Table below shows the nominal tooth dimensions for each of the standard belt sections. The tooth dimensions for double-sided belts are identical to those of a single-sided belt..
| NOMINAL TOOTH DIMENSIONS INCHES | |||||
| Belt Section | þ
Tooth Angle (Degrees) |
h t | b t | r a | r r |
| MXL (0.080) | 40 | 0.020 | 0.045 | 0.005 | 0.005 |
| XL (0.200) | 50 | 0.050 | 0.101 | 0.015 | 0.015 |
| L(0.375) | 40 | 0.075 | 0.183 | 0.020 | 0.020 |
| H (0.500) | 40 | 0.090 | 0.241 | 0.040 | 0.040 |
| XH (0.875) | 40 | 0.250 | 0.495 | 0.047 | 0.062 |
| XXH (1.250) | 40 | 0.375 | 0.750 | 0.060 | 0.090 |
| DXL(0.200) | 50 | 0.050 | 0.101 | 0.015 | 0.015 |
| DL (0.375) | 40 | 0.075 | 0.183 | 0.020 | 0.020 |
| DH (0.500) | 40 | 0.090 | 0.241 | 0.040 | 0.040 |
| HTD BELT DIMENSIONS | ||||||
| FINISHED BELT DIMENSIONS - TYPICAL BELT TOOTH DIMENSIONS | ||||||
| Tooth Type |
h
b Overall Thickness |
h t Tooth Depth |
"X" Ref. |
"Y" Ref. |
R1 Curve Rad11 |
R2 Curve Rad11 |
| 3mm | .095 ± .015 | .048 ± .004 | .0012 | .0137 | .034 | .012 |
| 5mm | .150 ± .025 | .082 ± .007 | .0020 | .0229 | .059 | .016 |
| 8mm | .236 ± .025 | .133 ± .009 | .0035 | .0310 | .102 | .030 |
| 14mm | .394 ± .025 | .237 ± .012 | .0060 | .0580 | .179 | .053 |
| 20mm | .520 ± .025 | .330 ± .025 | .0089 | .0743 | .256 | .075 |
Charts and Synchronous Belt information was abstracted from the RMA
1-800-THE-BELT (1-800-843-2358)
