188) In a disc clutch, if there are n₁ number of discs on the driving shaft and n₂ number of discs on the driven shaft, then the number of pairs of contact surfaces will be

189) The effect of swaying couple in a locomotive is resisted by the side pressure between the flanges of the tyres of the wheel and the inside of the rails.

190) The Klein's diagram is useful to find

191) The ratio of the number of teeth to the pitch circle diameter in millimetres, is called

192) The ratio of the pitch circle diameter in millimetres to the number of teeth, is called circular pitch.