422) The pitch diameter is the __________ diameter of an external or internal screw thread.

423) When percentage of carbon in steel is increased, the ductility of steel decreases.

424) The shock absorbing capacity of a bolt may be increased by

425) A lap joint is always in single shear.

426) If b denotes the face width and L denotes the cone distance for a bevel gear, then the bevel factor is written as