A pulley 250 mm diameter is driven directly by an electric motor at 420 revs min1. A

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Question:

A pulley 250 mm diameter is driven directly by an electric motor at 420 revs min–1. A v-belt is used to transmit power from this pulley to a second pulley 600 mm diameter against a load of 300 Nm. The distance between the center of the pulleys is 800 mm; the included angle of the pulley groove is 40°; the coefficient of friction between the belt and pulley is 0.35 and the ultimate strength of the belt is 10 kN.

a) Calculate the actual power transmitted to the second pulley.

(b) Calculate the power which can be transmitted if the maximum tension in the belt is limited to half of the ultimate strength of the belt.

(c) Giving reasons for your answer, what would be the effect of the following factors on the maximum power which can be transmitted:
(i) increasing the coefficient of friction;
(ii) increasing the included angle of the pulley groove.

(d) Giving reasons for your answer, if the load torque is increased and the speed maintains constant, what would be the effect on the following:
(i) the tension in the tight side of the belt;
(ii) the tension in the slack side of the belt;
(iii) the power transmitted.