— Belts, Chains & Gears
V-Belt Cross-Section Standards
| Section | Top Width | Height | Typical Power Range |
|---|---|---|---|
| A | 1/2" (13 mm) | 5/16" (8 mm) | ~0.9–10.2 HP |
| B | 21/32" (17 mm) | 13/32" (11 mm) | ~1.6–16.3 HP |
| C | 7/8" (22 mm) | 17/32" (14 mm) | ~6.9–31.8 HP |
| D | 1-1/4" (32 mm) | 3/4" (19 mm) | ~25–100 HP (indicative) |
| E | 1-1/2" (40 mm) | 29/32" (25 mm) | ~50–200+ HP (indicative) |
| 3V (narrow) | 3/8" (9.7 mm) | 5/16" (8 mm) | ~1.4–14.2 HP |
| 5V (narrow) | 5/8" (15.8 mm) | 17/32" (14 mm) | ~8.2–30.8 HP |
| 8V (narrow) | 1" (25.4 mm) | 7/8" (23 mm) | Similar to 5V-class, higher end |
Timing Belt Pitch Standards
| Designation | Pitch | Family | Typical Use |
|---|---|---|---|
| MXL | 0.080" (2.032 mm) | Inch trapezoidal | Miniature, light instruments |
| XL | 0.200" (5.080 mm) | Inch trapezoidal | Light duty |
| L | 0.375" (9.525 mm) | Inch trapezoidal | Medium load |
| H | 0.500" (12.700 mm) | Inch trapezoidal | Heavy duty |
| XH | 0.875" (22.225 mm) | Inch trapezoidal | Extra heavy duty |
| T2.5 / T5 / T10 | 2.5 / 5 / 10 mm | Metric trapezoidal | Miniature to medium-heavy (not interchangeable with same-number HTD) |
| HTD 3M / 5M / 8M / 14M | 3 / 5 / 8 / 14 mm | Curvilinear (Gates HTD) | Light to heavy duty — 8M is the most common industrial pitch |
| GT2 2mm / 3mm / 5mm | 2 / 3 / 5 mm | Curvilinear (Gates GT2) | Small automation/3D printing to precision positioning |
ANSI Roller Chain Standards
| Chain No. | Pitch | Avg. Tensile Strength | Typical Use |
|---|---|---|---|
| 25 | 0.250" | 780 lbf | Miniature machinery, light instruments |
| 35 | 0.375" | 1,760 lbf | Light-duty conveyors |
| 40 | 0.500" | 3,125 lbf | General light industrial |
| 50 | 0.625" | 4,880 lbf | General industrial |
| 60 | 0.750" | 7,030 lbf | Medium industrial drives |
| 80 | 1.000" | 12,500 lbf | Heavy-duty industrial |
| 100 | 1.250" | 19,530 lbf | Heavy machinery |
| 120 | 1.500" | 28,125 lbf | Heavy machinery, high torque |
| 140 | 1.750" | 38,280 lbf | Very heavy-duty |
| 160 | 2.000" | 50,000 lbf | Maximum standard single-strand duty |
See the Belt/Chain Drive Sizing calculator to size a drive from center distance, ratio, and speed/power.
Gear Tooth Standards
Diametral pitch (P) = teeth per inch of pitch diameter (US customary), higher P = smaller teeth. Module (m) = mm of pitch diameter per tooth (metric), higher m = larger teeth. Conversion: m = 25.4 / P.
| Standard Modules (mm) | Standard Diametral Pitches (coarse) | Standard Diametral Pitches (fine) |
|---|---|---|
| 0.5, 0.6, 0.8, 1, 1.25, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 10, 12, 16, 20 | 1, 1.25, 1.5, 2, 2.5, 3, 4, 6, 8, 10, 12, 16, 20 | 20, 24, 32, 40, 48, 64, 72, 80, 96, 120 |
20° pressure angle is the modern AGMA-preferred standard for spur/helical gears (since AGMA 2001-B88) — higher load capacity, better lubrication characteristics, and fewer pinion teeth possible without undercutting. 14.5° was the older standard, discontinued as a dedicated specification in the early 1970s; still stocked for legacy replacement but obsolete for new designs.
See the Gear Design calculator to size a gear mesh, and Gear Train Speed & Torque to solve output speed/torque through a gear train.