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A shaft runs at 300 rev/min and transmits power from a pulley A at one end to two
pulleys, B and C, which each drive a machine in a workshop. The distance between
pulleys A and B is 3 m and that between B and C is 2.4 m (i.e. the total length of the
shaft is 5.4 m). The shaft has a diameter of 50 mm between A and B and a diameter
of 40 mm between B and C. If the maximum permissible shear stress in the shaft is 80
MPa, calculate the maximum power which may be supplied from each of the pulleys B
an C, assuming that both machines would be in operation at the same time. Also
calculate the total angle of twist of one en
d of the shaft relative to the other when
running on full load. G = 80 (GPa)
Answers:
(30.2 kW; 31.4 kW; 13.7°)
Attached is my working, i can arrive at the answer of 31.4KW for the pulley at C at the smaller diameter step, however when i try the same calculate with the second moment of area (J) for the larger diameter i get an answer in excess of 60000KW. How would i calculate the torque for the larger diameter section?
as you can see from my working ive used the standard formula rearranged for torque, then used the standard power equation.
Thanks
pulleys, B and C, which each drive a machine in a workshop. The distance between
pulleys A and B is 3 m and that between B and C is 2.4 m (i.e. the total length of the
shaft is 5.4 m). The shaft has a diameter of 50 mm between A and B and a diameter
of 40 mm between B and C. If the maximum permissible shear stress in the shaft is 80
MPa, calculate the maximum power which may be supplied from each of the pulleys B
an C, assuming that both machines would be in operation at the same time. Also
calculate the total angle of twist of one en
d of the shaft relative to the other when
running on full load. G = 80 (GPa)
Answers:
(30.2 kW; 31.4 kW; 13.7°)
Attached is my working, i can arrive at the answer of 31.4KW for the pulley at C at the smaller diameter step, however when i try the same calculate with the second moment of area (J) for the larger diameter i get an answer in excess of 60000KW. How would i calculate the torque for the larger diameter section?
as you can see from my working ive used the standard formula rearranged for torque, then used the standard power equation.
Thanks
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