Overview and comparison
What are HTD timing pulleys?
HTD (High Torque Drive) is a metric synchronous profile with a rounded (parabolic) tooth form. Unlike Imperial profiles (MXL/XL/L/H), HTD teeth have greater depth and a rounded shape, which reduces bending stress and allows higher torque transmission at the same size. Pitches are metric: 3M (3 mm), 5M (5 mm), 8M (8 mm), 14M (14 mm).
Pulleys in this series have a pilot (centre) bore — supplied with a bore that is subsequently machined to the required shaft diameter. Materials: aluminium UNI 9006-T6 (small 3M and 5M series) and steel / grey cast iron (larger 5M, 8M, 14M series).
HTD advantages over Imperial profiles
| Criterion | HTD (3M/5M/8M/14M) | Imperial (L/H/XH) |
|---|---|---|
| Tooth form | Rounded (parabolic) | Trapezoidal |
| Bending stress | Lower | Higher |
| Torque at same size | Higher | Lower |
| Pitch system | Metric (3/5/8/14 mm) | Imperial (9.525/12.7/22.225 mm) |
| Prevalence | Widely used in modern machinery | Traditional machinery |
| Compatibility | HTD belts only | Imperial belts only |
- Lower bending stress on the tooth thanks to the parabolic form
- Higher transmitted torque for the same pulley size
- Metric pitch system (3/5/8/14 mm), widely used in modern machinery
- Precise centring via a pilot bore, machined to the shaft diameter
Series and catalogue data
Series and technical data
The profiles cover metric pitch from 3 to 14 mm, 10 to 192 teeth, in aluminium, steel and cast iron:
| Profile | Pitch | Widths (F mm) | Teeth | Material |
|---|---|---|---|---|
| HTD 3M | 3.0 mm | 9.0 mm (09) / 15.0 mm (15) | 10–72 | Aluminium UNI 9006-T6 |
| HTD 5M | 5.0 mm | 9.0 mm (09) / 15.0 mm (15) / 25.0 mm (25) | 12–72 | Steel (up to 40 teeth) / Aluminium (≥44) |
| HTD 8M | 8.0 mm | 20 / 30 / 50 / 85 mm | 22–192 | Steel (≤48–56) / Cast iron (≥80–90) |
| HTD 14M | 14.0 mm | 40 / 55 / 85 / 115 / 170 mm | 28–192 | Steel (≤44–56) / Cast iron (≥48–64) |
Catalogue data — HTD 3M width 09
Aluminium, F = 10.2 mm · Pilot bore, 10–72 teeth
| Code | Type | Teeth | dp (mm) | de (mm) | Df (mm) | Dm (mm) | F (mm) | L (mm) | d (mm) | Kg |
|---|---|---|---|---|---|---|---|---|---|---|
| 10 3M 09 | 1F | 10 | 9.55 | 8.79 | 13.0 | 12.0 | 10.2 | 17.5 | — | 0.01 |
| 12 3M 09 | 1F | 12 | 11.46 | 10.70 | 15.0 | 15.0 | 10.2 | 17.5 | — | 0.01 |
| 14 3M 09 | 1F | 14 | 13.37 | 12.61 | 16.0 | 16.0 | 10.2 | 17.5 | — | 0.01 |
| 15 3M 09 | 1F | 15 | 14.32 | 13.56 | 18.0 | 17.5 | 10.2 | 17.5 | — | 0.01 |
| 16 3M 09 | 2F | 16 | 15.28 | 14.52 | 18.0 | 10.0 | 12.8 | 20.6 | 4 | 0.01 |
| 18 3M 09 | 2F | 18 | 17.19 | 16.43 | 19.5 | 11.0 | 12.8 | 20.6 | 6 | 0.01 |
| 20 3M 09 | 2F | 20 | 19.10 | 18.34 | 23.0 | 13.0 | 12.8 | 20.6 | 6 | 0.01 |
| 22 3M 09 | 2F | 22 | 21.01 | 20.25 | 25.0 | 14.0 | 12.8 | 20.6 | 6 | 0.01 |
| 24 3M 09 | 2F | 24 | 22.92 | 22.16 | 25.0 | 14.0 | 12.8 | 20.6 | 6 | 0.02 |
| 28 3M 09 | 2F | 28 | 26.74 | 25.98 | 32.0 | 18.0 | 12.8 | 20.6 | 6 | 0.02 |
| 30 3M 09 | 2F | 30 | 28.65 | 27.89 | 32.0 | 20.0 | 12.8 | 20.6 | 6 | 0.03 |
| 36 3M 09 | 2F | 36 | 34.38 | 33.62 | 38.0 | 26.0 | 13.4 | 22.2 | 6 | 0.05 |
| 40 3M 09 | 2F | 40 | 38.20 | 37.44 | 42.0 | 28.0 | 13.4 | 22.2 | 6 | 0.06 |
| 44 3M 09 | 2F | 44 | 42.02 | 41.26 | 48.0 | 33.0 | 13.4 | 22.2 | 6 | 0.07 |
| 48 3M 09 | 2 | 48 | 45.84 | 45.08 | — | 33.0 | 13.4 | 22.2 | 8 | 0.11 |
| 60 3M 09 | 2 | 60 | 57.30 | 56.54 | — | 33.0 | 13.4 | 22.2 | 8 | 0.11 |
| 72 3M 09 | 2 | 72 | 68.76 | 68.00 | — | 33.0 | 13.4 | 22.2 | 8 | 0.15 |
Catalogue data — HTD 3M width 15
Aluminium, F = 17.0–19.5 mm · Wider version for higher power
| Code | Type | Teeth | dp (mm) | de (mm) | Df (mm) | Dm (mm) | F (mm) | L (mm) | d (mm) | Kg |
|---|---|---|---|---|---|---|---|---|---|---|
| 10 3M 15 | 1F | 10 | 9.55 | 8.79 | 13.0 | 12.0 | 17.0 | 26.0 | — | 0.01 |
| 14 3M 15 | 1F | 14 | 13.37 | 12.61 | 16.0 | 16.0 | 17.0 | 26.0 | — | 0.01 |
| 16 3M 15 | 2F | 16 | 15.28 | 14.52 | 18.0 | 10.0 | 19.5 | 26.0 | 4 | 0.01 |
| 20 3M 15 | 2F | 20 | 19.10 | 18.34 | 23.0 | 13.0 | 19.5 | 26.0 | 6 | 0.01 |
| 24 3M 15 | 2F | 24 | 22.92 | 22.16 | 25.0 | 14.0 | 19.5 | 26.0 | 6 | 0.02 |
| 28 3M 15 | 2F | 28 | 26.74 | 25.98 | 32.0 | 18.0 | 19.5 | 26.0 | 6 | 0.03 |
| 32 3M 15 | 2F | 32 | 30.56 | 29.80 | 36.0 | 22.0 | 19.5 | 26.0 | 6 | 0.04 |
| 36 3M 15 | 2F | 36 | 34.38 | 33.62 | 38.0 | 26.0 | 20.0 | 30.0 | 6 | 0.06 |
| 40 3M 15 | 2F | 40 | 38.20 | 37.44 | 42.0 | 28.0 | 20.0 | 30.0 | 6 | 0.08 |
| 44 3M 15 | 2F | 44 | 42.02 | 41.26 | 48.0 | 33.0 | 20.0 | 30.0 | 6 | 0.10 |
| 48 3M 15 | 2 | 48 | 45.84 | 45.08 | — | 33.0 | 20.0 | 30.0 | 8 | 0.10 |
| 60 3M 15 | 2 | 60 | 57.30 | 56.54 | — | 33.0 | 20.0 | 30.0 | 8 | 0.15 |
| 72 3M 15 | 2 | 72 | 68.76 | 68.00 | — | 33.0 | 20.0 | 30.0 | 8 | 0.21 |
Catalogue data — HTD 5M width 09
Steel (12–40 teeth) / Aluminium (44–72 teeth), F = 14.5 mm
| Code | Type | Mat. | Teeth | dp (mm) | de (mm) | Df (mm) | Dm (mm) | Di (mm) | F (mm) | L (mm) | d (mm) | Kg |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 12 5M 09 | 2F | St | 12 | 19.10 | 17.96 | 23 | 12.5 | — | 14.5 | 20.0 | 6 | 0.03 |
| 15 5M 09 | 2F | St | 15 | 23.87 | 22.73 | 28 | 16.0 | — | 14.5 | 20.0 | 6 | 0.05 |
| 18 5M 09 | 2F | St | 18 | 28.65 | 27.51 | 32 | 20.0 | — | 14.5 | 20.0 | 6 | 0.07 |
| 20 5M 09 | 2F | St | 20 | 31.83 | 30.69 | 36 | 23.0 | — | 14.5 | 22.5 | 6 | 0.10 |
| 24 5M 09 | 2F | St | 24 | 38.20 | 37.06 | 42 | 27.0 | — | 14.5 | 22.5 | 6 | 0.15 |
| 28 5M 09 | 2F | St | 28 | 44.56 | 43.42 | 48 | 30.5 | — | 14.5 | 22.5 | 6 | 0.21 |
| 30 5M 09 | 2F | St | 30 | 47.75 | 46.60 | 51 | 35.0 | — | 14.5 | 22.5 | 6 | 0.25 |
| 36 5M 09 | 2F | St | 36 | 57.30 | 56.16 | 60 | 38.0 | — | 14.5 | 22.5 | 8 | 0.33 |
| 40 5M 09 | 2F | St | 40 | 63.66 | 62.52 | 71 | 38.0 | — | 14.5 | 22.5 | 8 | 0.42 |
| 44 5M 09 | 2 | Al | 44 | 70.03 | 68.89 | — | 38.0 | — | 14.5 | 25.5 | 8 | 0.17 |
| 48 5M 09 | 2 | Al | 48 | 76.39 | 75.25 | — | 45.0 | — | 14.5 | 25.5 | 8 | 0.18 |
| 60 5M 09 | 2 | Al | 60 | 95.49 | 94.35 | — | 45.0 | — | 14.5 | 25.5 | 8 | 0.23 |
| 72 5M 09 | 2 | Al | 72 | 114.59 | 113.45 | — | 45.0 | — | 14.5 | 25.5 | 8 | 0.42 |
Catalogue data — HTD 5M width 25
Steel (12–40 teeth) / Aluminium (44–72 teeth), F = 30.5 mm
| Code | Type | Mat. | Teeth | dp (mm) | de (mm) | Df (mm) | Dm (mm) | Di (mm) | F (mm) | L (mm) | d (mm) | Kg |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 12 5M 25 | 2F | St | 12 | 19.10 | 17.96 | 23 | 12.5 | — | 30.5 | 36 | 6 | 0.05 |
| 15 5M 25 | 2F | St | 15 | 23.87 | 22.73 | 28 | 16.0 | — | 30.5 | 36 | 6 | 0.09 |
| 20 5M 25 | 2F | St | 20 | 31.83 | 30.69 | 36 | 23.0 | — | 30.5 | 36 | 6 | 0.17 |
| 24 5M 25 | 2F | St | 24 | 38.20 | 37.06 | 42 | 27.0 | — | 30.5 | 38 | 6 | 0.26 |
| 28 5M 25 | 2F | St | 28 | 44.56 | 43.42 | 48 | 30.5 | — | 30.5 | 38 | 6 | 0.37 |
| 32 5M 25 | 2F | St | 32 | 50.93 | 49.79 | 54 | 38.0 | — | 30.5 | 38 | 8 | 0.48 |
| 36 5M 25 | 2F | St | 36 | 57.30 | 56.16 | 60 | 38.0 | — | 30.5 | 38 | 8 | 0.59 |
| 40 5M 25 | 2F | St | 40 | 63.66 | 62.52 | 71 | 38.0 | — | 30.5 | 38 | 8 | 0.75 |
| 44 5M 25 | 2 | Al | 44 | 70.03 | 68.89 | — | 38.0 | — | 30.5 | 40 | 8 | 0.32 |
| 60 5M 25 | 2 | Al | 60 | 95.49 | 94.35 | — | 50.0 | — | 30.5 | 40 | 8 | 0.44 |
| 72 5M 25 | 2 | Al | 72 | 114.59 | 113.45 | — | 50.0 | — | 30.5 | 40 | 8 | 0.85 |
Catalogue data — HTD 8M width 20
Types: 2F (steel, ≤48 teeth) · 3F (steel, 56–72 teeth) · 3 (cast iron, ≥80 teeth). F = 28 mm
| Code | Type | Mat. | Teeth | dp (mm) | de (mm) | Df (mm) | Dm (mm) | Di (mm) | F (mm) | L (mm) | d (mm) | Kg |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 22 8M 20 | 2F | St | 22 | 56.02 | 54.65 | 60 | 43 | — | 28 | 38 | 12 | 0.54 |
| 26 8M 20 | 2F | St | 26 | 66.21 | 64.84 | 71 | 48 | — | 28 | 38 | 12 | 0.80 |
| 30 8M 20 | 2F | St | 30 | 76.39 | 75.13 | 83 | 55 | — | 28 | 38 | 14 | 1.00 |
| 36 8M 20 | 2F | St | 36 | 91.67 | 90.30 | 98 | 70 | — | 28 | 38 | 14 | 1.60 |
| 40 8M 20 | 2F | St | 40 | 101.86 | 100.49 | 106 | 75 | — | 28 | 38 | 14 | 1.85 |
| 48 8M 20 | 2F | St | 48 | 122.23 | 120.86 | 127 | 75 | — | 28 | 38 | 14 | 2.50 |
| 56 8M 20 | 3F | St | 56 | 142.60 | 141.23 | 148 | 80 | 116 | 28 | 38 | 14 | 2.82 |
| 64 8M 20 | 3F | St | 64 | 162.97 | 161.60 | 168 | 80 | 137 | 28 | 38 | 14 | 3.22 |
| 72 8M 20 | 3F | St | 72 | 183.35 | 181.97 | 192 | 80 | 158 | 28 | 38 | 14 | 3.74 |
| 80 8M 20 | 3 | GG | 80 | 203.72 | 202.35 | — | 90 | 180 | 28 | 38 | 14 | 3.78 |
| 90 8M 20 | 3 | GG | 90 | 229.18 | 227.81 | — | 90 | 204 | 28 | 38 | 14 | 4.57 |
Catalogue data — HTD 8M width 50
Steel / cast iron, F = 60 mm · Up to 192 teeth
| Code | Type | Mat. | Teeth | dp (mm) | de (mm) | Df (mm) | Dm (mm) | Di (mm) | F (mm) | L (mm) | d (mm) | Kg |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 22 8M 50 | 2F | St | 22 | 56.02 | 54.65 | 60 | 43 | — | 60 | 70 | 12 | 1.10 |
| 28 8M 50 | 2F | St | 28 | 71.30 | 70.08 | 75 | 50 | — | 60 | 70 | 14 | 1.70 |
| 36 8M 50 | 2F | St | 36 | 91.67 | 90.30 | 98 | 70 | — | 60 | 70 | 14 | 3.10 |
| 44 8M 50 | 2F | St | 44 | 112.05 | 110.67 | 119 | 75 | — | 60 | 70 | 14 | 4.40 |
| 56 8M 50 | 7F | St | 56 | 142.60 | 141.23 | 148 | 90 | 116 | 60 | 60 | 18 | 5.68 |
| 64 8M 50 | 7F | St | 64 | 162.97 | 161.60 | 168 | 100 | 137 | 60 | 60 | 18 | 6.93 |
| 72 8M 50 | 7F | St | 72 | 183.35 | 181.97 | 192 | 100 | 158 | 60 | 60 | 18 | 7.95 |
| 80 8M 50 | 7 | GG | 80 | 203.72 | 202.35 | — | 110 | 180 | 60 | 60 | 18 | 7.96 |
| 112 8M 50 | 8 | GG | 112 | 285.21 | 283.83 | — | 110 | 254 | 60 | 60 | 18 | 12.16 |
| 144 8M 50 | 8 | GG | 144 | 366.69 | 365.32 | — | 110 | 336 | 60 | 60 | 20 | 15.68 |
| 192 8M 50 | 8 | GG | 192 | 488.92 | 487.55 | — | 130 | 460 | 60 | 60 | 20 | 24.09 |
Catalogue data — HTD 14M width 40
Types: 2F (steel) · 3F (cast iron, 48–64 teeth) · 4 (cast iron, ≥72 teeth). F = 54 mm
| Code | Type | Mat. | Teeth | dp (mm) | de (mm) | Df (mm) | Dm (mm) | Di (mm) | F (mm) | L (mm) | d (mm) | Kg |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 28 14M 40 | 2F | St | 28 | 124.78 | 122.12 | 127 | 100 | — | 54 | 69 | 24 | 4.80 |
| 32 14M 40 | 2F | St | 32 | 142.60 | 139.88 | 154 | 100 | — | 54 | 69 | 24 | 6.20 |
| 36 14M 40 | 2F | St | 36 | 160.43 | 157.68 | 168 | 100 | — | 54 | 69 | 24 | 7.70 |
| 40 14M 40 | 2F | St | 40 | 178.25 | 175.49 | 188 | 120 | — | 54 | 69 | 24 | 9.80 |
| 44 14M 40 | 2F | St | 44 | 196.08 | 193.28 | 211 | 120 | — | 54 | 69 | 24 | 12.00 |
| 48 14M 40 | 3F | GG | 48 | 213.90 | 211.11 | 226 | 135 | 170 | 54 | 69 | 24 | 11.98 |
| 56 14M 40 | 3F | GG | 56 | 249.55 | 246.76 | 256 | 135 | 207 | 54 | 69 | 28 | 14.01 |
| 64 14M 40 | 3F | GG | 64 | 285.21 | 282.41 | 296 | 135 | 240 | 54 | 69 | 28 | 16.65 |
| 72 14M 40 | 4 | GG | 72 | 320.86 | 318.06 | — | 135 | 278 | 54 | 69 | 28 | 15.52 |
| 90 14M 40 | 4 | GG | 90 | 401.07 | 398.28 | — | 135 | 358 | 54 | 69 | 28 | 19.40 |
| 112 14M 40 | 4 | GG | 112 | 499.11 | 496.32 | — | 135 | 456 | 54 | 69 | 28 | 24.14 |
Catalogue data — HTD 14M width 115
Steel / cast iron, F = 133 mm · Up to 192 teeth
| Code | Type | Mat. | Teeth | dp (mm) | de (mm) | Df (mm) | Dm (mm) | Di (mm) | F (mm) | L (mm) | d (mm) | Kg |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 28 14M 115 | 2F | St | 28 | 124.78 | 122.12 | 127 | 100 | — | 133 | 148 | 32 | 10.75 |
| 32 14M 115 | 2F | St | 32 | 142.60 | 139.88 | 154 | 100 | — | 133 | 148 | 32 | 14.48 |
| 36 14M 115 | 2F | St | 36 | 160.43 | 157.68 | 168 | 120 | — | 133 | 148 | 32 | 18.99 |
| 40 14M 115 | 2F | St | 40 | 178.25 | 175.49 | 188 | 135 | — | 133 | 148 | 32 | 24.04 |
| 44 14M 115 | 2F | St | 44 | 196.08 | 193.28 | 211 | 140 | — | 133 | 148 | 32 | 29.41 |
| 48 14M 115 | 2F | St | 48 | 213.90 | 211.11 | 226 | 150 | — | 133 | 148 | 32 | 35.00 |
| 56 14M 115 | 2F | St | 56 | 249.55 | 246.76 | 256 | 150 | — | 133 | 148 | 32 | 48.00 |
| 64 14M 115 | 7F | GG | 64 | 285.21 | 282.41 | 296 | 150 | 240 | 133 | 133 | 32 | 36.00 |
| 72 14M 115 | 8 | GG | 72 | 320.86 | 318.06 | — | 150 | 278 | 133 | 133 | 32 | 36.00 |
| 90 14M 115 | 8 | GG | 90 | 401.07 | 398.28 | — | 150 | 358 | 133 | 133 | 32 | 45.00 |
| 112 14M 115 | 8 | GG | 112 | 499.11 | 496.32 | — | 150 | 456 | 133 | 133 | 32 | 55.50 |
| 144 14M 115 | 8 | GG | 144 | 641.71 | 638.92 | — | 165 | 600 | 133 | 133 | 32 | 71.00 |
| 192 14M 115 | 8 | GG | 192 | 855.62 | 852.82 | — | 165 | 813 | 133 | 133 | 32 | 96.00 |
Formulas and flanges
Pitch diameter formula
dp = (z × p) / π, where z = number of teeth, p = pitch in mm. Examples: 24 teeth HTD 5M → dp = (24×5)/π = 38.20 mm | 36 teeth HTD 8M → dp = (36×8)/π = 91.67 mm | 40 teeth HTD 14M → dp = (40×14)/π = 178.25 mm.
Flange types
| Code | Description | Typical application |
|---|---|---|
| 1F | 1 flange (single-sided) | HTD 3M small pulleys |
| 2F | 2 flanges (double-sided) — standard | HTD 5M, 8M, 14M steel |
| 2 | No flange — plain body | HTD 3M/5M Al (higher tooth counts) |
| 3F | 3 flanges + inner disc (Di) | HTD 8M steel 56–72 teeth |
| 3 | Cast iron with Di, no flange | HTD 8M GG ≥80 teeth |
| 4 | Cast iron without flange, with Di | HTD 8M/14M GG ≥112 teeth |
| 7F | 7 flanges + Di | HTD 8M/14M 50/85mm ≥56 teeth |
| 7 | GG no flange with Di | HTD 8M/14M GG ≥80 teeth |
| 8 | GG no flange with Di (heavy) | HTD 8M/14M GG ≥112 teeth |
HTD timing pulleys, pilot bore
Download PDF ↓Frequently Asked Questions
What is the difference between HTD and Imperial (L/H) profiles?
HTD profiles have metric pitch (3/5/8/14 mm) and a rounded parabolic tooth — lower bending stress, higher torque capacity at the same size. Imperial profiles (L=9.525 mm, H=12.7 mm) have a trapezoidal tooth and inch-based pitch. The two types are NOT interchangeable — pulley and belt must have the same profile and pitch.
How is the pitch diameter of an HTD pulley calculated?
dp = (z × p) / π. For HTD 5M with 24 teeth: dp = (24×5)/π = 38.20 mm. For HTD 8M with 36 teeth: dp = (36×8)/π = 91.67 mm. For HTD 14M with 40 teeth: dp = (40×14)/π = 178.25 mm. Transmission ratio: i = z2/z1 — calculated from tooth counts, no slip.
Which HTD profile should I choose — 5M, 8M or 14M?
HTD 3M/5M: precision drives with low to medium power — robotics, CNC, packaging machines. HTD 8M: medium to high power — conveyors, industrial machines. HTD 14M: very high power and torque — heavy engineering, agricultural machinery. Larger pitch = higher torque, but also larger minimum diameter.
Can pulleys be bored to a specific shaft diameter?
Yes — pulleys are supplied with a pilot bore and machined to the required diameter. When ordering, specify: profile, tooth count, width, shaft diameter. Contact: nibora@nibora.com, +359 64 681 058.