| Gears |   | 
 
| Symbol | Description | Units | 
|---|---|---|
| T1 | Applied torque to drive gear | Nm | 
| n1 | Speed of drive gear | rpm | 
| r1 | Effective radius of drive gear | m | 
| Fa | Axial force | N | 
| Fr | Radial force | N | 
| Ft | Tangential force (effective force that does useful work) | N | 
| Fn | Total force (force normal to the tooth surface) | N | 
| a | Pressure angle | o | 
| b | Helix angle | o |