Question

Question 9 (9] The shaft shown in fiqure Q9 receives 80 kW from a water turbine through a chain sprocket at point C. The gear pair at E delivers 60 kW to an electrical generator. The V-belt sheave at A de- livers 20 kW to a bucket elevator that carries grain to an elevated hopper. The shaft rotates at 1700 rpm. The sprocket, sheave and gear are located axially by retaining rings. The sheave and gear are keyed with sled runner keyseats, and there is a profile keyseat at the sprocket. Use AlSi 1040 cold-drawn steel for the shaft with vield strength (S) of 490 MPa and a corrected fatigue strength (S) of 140 MPa. The design factor of safety to be used is 2. The shaft is to be designed for repeated torsion (alternating and mean components are of equal magnitude) and fully re- versed bending. Determine the minimum acceptable diameter Da at point C for a steady torsion and fully re- versed bending. At this point, K, Km = 3, Kts Km 1 and the bending moment diagram is also shown in the figure. 6.00 6.00 -6,00 6.00 Bearing rD- D1 DI N Bearing 14 TN LDs ND D Spur gear 20° FD 12.00 in PD V-bclt sheave 6.00 in PD Chain sprocket 10.00 in PD 540 Nm 380 Nm 350 Nm A E Figure Q9 End

Answer 1

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