228) The shock resistance of steel is increased by adding

229) A flange coupling is a type of rigid coupling.

230) The strength of the un-riveted plate (P) per pitch length is equal to

231) Two shafts of the same length and material are joined in series. If the ratio of their diameters is 2, then the ratio of their angles of twist will be

232) Wahl's stress factor __________ very rapidly as the spring index decreases.