In the following example, a ZIMM bevel gearbox ZK-065 with a drive ratio of 2:1 is checked by calculation for a three-phase motor with fan. The selection is carried out by calculating input torque, output torque, output power, factors, design torque and thermal limit power. The calculated values are then compared with the permissible values.
Which initial data are used for the calculated selection of a ZIMM bevel gearbox of the ZK Series
| Initial variable | Value |
| Application | Three-phase motor for fan |
| Input power | 0,75 kW |
| Input speed | 1390 upm |
| Operation | 16 h/d |
| Duty factor | max. 100 % ED / 10 min |
| Starts per hour | max. 100 c/h |
| Fan speed | 500–750 upm |
| Ambient temperature | 20 °C |
| Radial force at output shaft | 350 N |
| Checked size and drive ratio | ZK-065, 2:1 |
How are input, output and factors calculated in the example?
1. Calculate input torque
TD = 0,75 kW × 9550 / 1390 min⁻¹
TD = 5,15 Nm
2. Calculate output torque
TAC = 5,15 Nm × 2 × 0,97
TAC = 10,0 Nm
3. Calculate output power
PAC = 10,0 Nm × 695 min⁻¹ / 9550
PAC = 0,73 kW
4. Include factors
fb = 1,1
fd = 1,15
ft = 1,0
fe = 1,0
5. Calculate design torque
Ta;AC = 10,0 Nm × 1,1 × 1,15 × 1,0
Ta;AC = 12,65 Nm
6. Calculate thermal limit power
Pt = 0,73 kW × 1,15 × 1,0 × 1,0
Pt = 0,84 kW
Which check criteria are compared in the calculated selection of a ZIMM bevel gearbox of the ZK Series?
The comparison is carried out using design torque, radial force, thermal limit power and the 80% limit of the thermal limit power.
| Check criterion | Calculated value | Permissible value | Assessment |
| Design torque Ta;AC | 12,65 Nm | 14,5 Nm | fulfilled |
| Radial force Fr;AC | 350 N | 390 N | fulfilled |
| Thermal limit power Pt | 0,84 kW | 1,3 kW | fulfilled |
| 80% limit of the thermal limit power | 0,84 kW | 1,04 kW | fulfilled |
