Technical Data Synchronous Belts / Belt Sprockets Selection
Synchronous belt Correction Factors
Table 1: Service correction factor Ko
| Ratio of max. load output to motor rated output |
≦200% |
201%～249% |
250%≦ |
| Operation hours per day h |
＜3 |
3～10 |
10＜ |
＜3 |
3～10 |
10＜ |
＜3 |
3～10 |
10＜ |
| Type of load and examples of application |
Smooth
ex. ：Measuring instruments, medical equipment, agitators |
1.2 |
1.3 |
1.4 |
1.3 |
1.4 |
1.4 |
1.4 |
1.5 |
1.6 |
Moderate shock
ex. ：Injection molding machines, machine tools, conveyors, pumps |
1.3 |
1.4 |
1.5 |
1.4 |
1.5 |
1.6 |
1.5 |
1.6 |
1.7 |
Large impact
ex. ：Robots, high-speed press machines, intermittently driven conveyors |
1.4 |
1.5 |
1.6 |
1.6 |
1.6 |
1.7 |
1.7 |
1.7 |
1.8 |
For drive that is subjected to very strong shock, a factor greater than 1.8 may be required. Please contact a Tsubaki representative for the use of such application.
Table 2: Correction factor when idler is used Ki
| Idler use position |
Inside |
outside |
| Slack side of belt |
0 |
+0.1 |
| Tension side of belt |
+0.1 |
+0.2 |
Table 3: Correction factor for speed increase Ks
| Increase ratio |
Correction factor |
| 1 or more, less than 1.25 |
0 |
| 1.25 or more, less than 1.75 |
+0.2 |
| 1.75 or more, less than 2.5 |
+0.3 |
| 2.5 or more, less than 3.5 |
+0.4 |
| 3.5 or more |
+0.5 |
Table 4: Start-stop frequency correction factor Ka
| Frequency of start-stop per day |
≦10 |
11～100 |
101～999 |
1000≦ |
| Ratio of max. output to motor rated output |
≦200% |
1.2 |
1.3 |
1.4 |
1.5 |
| 201%～249% |
1.3 |
1.4 |
1.5 |
1.6 |
| 250%≦ |
1.4 |
1.6 |
1.7 |
1.8 |
Table 5: Belt length correction factor KL
| Types (Pitch ) |
Belt length mm |
| ≦200 |
201～300 |
301～450 |
451～600 |
601～900 |
901～1300 |
1301～1800 |
1801≦ |
| P2M |
0.8 |
0.9 |
1.0 |
1.1 |
1.2 |
1.2 |
1.2 |
1.2 |
| P3M・UP3M |
0.8 |
0.9 |
1.0 |
1.1 |
1.2 |
1.2 |
1.2 |
1.2 |
| P5M・UP5M |
- |
0.8 |
0.8 |
0.9 |
1.0 |
1.1 |
1.2 |
1.2 |
| P8M・UP8M |
- |
- |
0.8 |
0.8 |
0.9 |
1.0 |
1.1 |
1.2 |
| P14M・UP14M |
- |
- |
- |
- |
- |
0.9 |
1.0 |
1.1 |
Table 6: Meshing correction factor Km
| Number of meshing teeth of small belt sprocket Zm |
6 or more |
5 |
4 |
| Meshing factor |
1.0 |
0.7 |
0.5 |
Note: If the number of meshing teeth of the belt and belt sprocket do not satisfy the following conditions, reconsider the layout.
- ・In the case of a drive belt sprocket, the engagement angle shall be 120° or larger, and the number of meshing teeth shall be six or more.
- ・In the case of a driven belt sprocket, the engagement angle shall be 90° or larger, and the number of meshing teeth shall be six or more
