The size selection of the pulleys and the idlers is instrumental to drive performance and service life. Minimum pulley diameter and number of teeth are in direct relation with the tooth pitch. It is recommended to aim always for a bigger pulley or idler size to avoid belt tension member fatigue. The chart below will tell you the minimum number of teeth for your belt pitch and configuration.
No Back Bending
Minimum # of teeth on pulley
No Back Bending
Min. diameter of flat idler (in mm)
With Back Bending
Minimum # of teeth on pulley
With Back Bending
Min. diameter of flat idler in mm
| Pitch | Min Teeth No Back Bending | Min Pulley Diameter No Back Bending | Min Teeth With Back Bending | Min Pulley Diameter With Back Bending |
|---|---|---|---|---|
| T2 | 10 | 15 | 18 | 15 |
| T2.5 | 10 | 18 | 15 | 18 |
| T5 | 10 | 15 | 30 | 30 |
| T10 | 12 | 20 | 60 | 60 |
| T20 | 15 | 25 | 120 | 120 |
| Min Teeth No Back Bending | Min Pulley Diameter (mm) No Back Bending | Min Teeth With Back Bending | Min Pulley Diameter (mm) With Back Bending | |
|---|---|---|---|---|
| AT3 | 15 | 25 | 30 | 30 |
| AT5 | 15 | 20 | 25 | 60 |
| AT10 | 15 | 50 | 25 | 120 |
| ATS15 | 25 | 40 | 120 | 250 |
| AT20 | 18 | 25 | 120 | 180 |
| ATN10 | 25 | -- | 80 | -- |
| ATN12.7 | 20 | -- | 80 | -- |
| ATN20 | 20 | -- | 125 | -- |
| ATP10 | 15 | 25 | 50 | 120 |
| ATP15 | 20 | 30 | 100 | 160 |
| Pitch | Min Teeth No Back Bending | Min Pulley Diameter No Back Bending | Mio Teeth With Back Bending | Min Pulley Diameter With Back Bending |
|---|---|---|---|---|
| MXL | 10 | 18 | 15 | 15 |
| XL | 10 | 15 | 30 | 30 |
| L | 15 | 20 | 60 | 60 |
| H | 14 | 20 | 60 | 80 |
| XH | 18 | 25 | 150 | 180 |
| Pitch | Min Teeth No Back Bending | Min Pulley Diameter No Back Bending | Mio Teeth With Back Bending | Min Pulley Diameter With Back Bending |
|---|---|---|---|---|
| BAT10 | 20 | 25 | 60 | 120 |
| BATK10 | 20 | 25 | 60 | 120 |
| BAT15 | 20 | 30 | 100 | 150 |
| BATK15 | 20 | 30 | 100 | 150 |
| SFAT10 | 15 | 25 | 50 | 120 |
| SFAT15 | 20 | 25 | 100 | 150 |
| SFAT20 | 18 | 25 | 120 | 180 |
| TK5 K6 | 25 | 25 | 60 | 80 |
| TK10 K6 | 25 | 25 | 60 | 80 |
| TK10 K13 | 25 | 25 | 80 | 120 |
| TK20 K13 | 18 | 25 | 120 | 180 |
| ATK5 K6 | 25 | 25 | 60 | 80 |
| ATK10 K6 | 25 | 25 | 60 | 120 |
| ATK10 K13 | 20 | 25 | 60 | 120 |
| ATK20 K13 | 20 | 25 | 120 | 180 |
| ATN10 K6 | 25 | -- | 80 | -- |
| ATN12.7 K6 | 20 | -- | 80 | -- |
| HK13 | 18 | 20 | 80 | 120 |
| LK13 | 25 | 25 | 80 | 80 |