3. Transmission angle y pressure angle a (传动角与压力角) Transmission angley: 1) Defined as the angle between the output link and coupler 2) Taken as the absolute value of the acute angle of the pair of angles at the intersection of the two links 3)Varies continuously from min, to max, value ) A measure of the quality of force transmission at the joint Pressure angle a The acute angle between the directions of the force and the velocity of the point receiving the force on the follower.Transmission angle  ： 1) Defined as the angle between the output link and coupler 2) Taken as the absolute value of the acute angle of the pair of angles at the intersection of the two links 3) Varies continuously from min.to max. value 4) A measure of the quality of force transmission at the joint Pressure angle  ： The acute angle between the directions of the force and the velocity of the point receiving the force on the follower. 3. Transmission angle  & Pressure angle  （传动角与压力角）