Chap, 5.2 The fundamental law of gearing(3) Point p is very important to the velocity ratio and it is called the pitch point For a constant velocity ratio, the position of P should remain unchanged The motion transmission between two gears is equivalent to the motion transmission between two imagined slipless cylinders with radius r, and r or diameter d, and d Two circles whose centers are at 0, and o and through pitch point p are termed pitch circles Pitch circles Pitch point Pitch circle Constant Angular Velocity Ratio▪ Point P is very important to the velocity ratio, and it is called the pitch point. ▪ For a constant velocity ratio, the position of P should remain unchanged. ▪ The motion transmission between two gears is equivalent to the motion transmission between two imagined slipless cylinders with radius r1 and r2 or diameter d1 and d2 . ▪Two circles whose centers are at O1 and O2 , and through pitch point P are termed pitch circles. Chap.5.2 The fundamental law of gearing(3) Pitch circles r1 r2 Pitch point Pitch circle Constant Angular Velocity Ratio P