1. The problem statement, all variables and given/known data 1. A pulley 150 mm diameter is driven directly by an electric motor at 250 revs min–1. A V-belt is used to transmit power from this pulley to a second pulley 400 mm diameter against a load of 200 Nm. The distance between the centre of the pulleys is 600 mm, the included angle of the pulley groove = 40°, the coefficient of friction between the belt and pulley is 0.4 and the ultimate strength of the belt is 8 kN. What would be the effect of the following factors on the maximum power which can be transmitted (give reasons for your answer): (i) increasing the coefficient of friction (ii) increasing the included angle of the pulley groove. 2. Relevant equations F1 / F2 = eµθ/ sinα 3. The attempt at a solution Increasing the coefficient of friction would increase the power up to a certain point. graph 1 shows this. however i'm having some trouble explaining why this is. Increasing the included angle of the pulley groove will have the effect of decreasing the power. again i have a graph which shows this, but cannot really explain why. can anyone advise?