| a | center distance between base circle and rolling circle | h | radius ratio of enveloping circle and rolling circle |
| k | reciprocal of curtate ratio | K | curtate ratio |
| L | distance from the point C to the center of rolling circle O2 | r1 | radius of base circle |
| r2 | radius of rolling circle | R | radius of enveloping circle (or cutter circle) |
| Q | instantaneous flow rate | φ1 | rotary angle of base circle |
| φ2 | rotary angle of rolling circle | θ | angle between line O2C and normal PC of trochoid |
| σQ | pulsation coefficient of flow rate |
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