Problem 10: A horizontal belt conveyor arranged as shown in Fig. 10 operates at a speed of 270fpm and requires 21HP at the 30" diameter driving drum. The drum receives power from a countershaft, through a pair of spur gears. A motor operating at 860rpm delivers power to the countershaft through a V-belt drive. The mechanical efficiency of the belt drive is 90% and of the gears 96%. a) Determine the horsepower of the motor. b) Calculate the diameter of the large pulley required to run the conveyor belt at the speed specified. c) Determine the torque on the countershaft corresponding to the rated horsepower of the motor. d) If the allowable shear stress is 5500 psi, determine the diameter of the countershaft. 24T 4P 124T Motor 18T 42** 5" Chain, 1 pitch Large sprocket Countershaft Drum Fig. 10 270 fpm Conveyor belt