66) The material used for brake lining should have __________ coefficient of friction.

67) Screws jacks have multiple threads.

68) In an ordinary bolt, the effect of the impulsive loads applied axially is concentrated on the cross-sectional area at the root of the threads.

69) The radial distance of a tooth from the pitch circle to the top of the tooth is called

70) In a gear, having involute teeth, the normal to the involute is a tangent to the