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1. A pinion shaft for a helical gear reducer is sketched in Figure Q1 (a), where the reaction forces on the pinion are also shown. The pinion shaft is to be driven at 600 rpm by a motor developing 20.9 kW. 140 mm -65 mm Driving pinion - Fy=-2047 N Fo=1502 N Fe = 3571 Ni с Figure Q1 (a) B (a) Construct shear, and bending moment diagrams for the shaft, in both the horizontal and the vertical plane, assuming that the bearing at the right end (nearest to the gear, point B) supports all thrust (axial) loading. [8 marks] (b) If the shaft is to be made of 1006 steel (Sy= 170 MPa, Sut= 300MPa, Se=150 MPa), and a design safety factor of 3.0 is desired, determine the minimum diameter required at location middle of two bearings to provide infinite life? [6 marks] Note: Use of marine factors such as surface and size factors can be ignored for this problem.
(C) The casing shown in Figure Q1 (b) is proposed for the shaft of Figure Q1 (a). The shaft should be supported by using two tapered roller bearings and one cylindrical roller bearing at housings allocated in the casing. Bearings should be able to carry all the loads even if the shaft direction reversed. i) Figure Q1 (b) Place the bearings in the housings of the casing at correct location and orientation. [2 marks] ii) Design a shaft to locate bearings, gears, and other necessary parts. [2 marks] iii) Complete the design of the assembly by use of other machine elements such as casing lid, lock nut, lip seal, screw, etc. (label all parts on the drawing). [3 marks] iv) Briefly explain how the bearings arrangement in your design will satisfy the needs to carry loads and to accommodate the thermal expansion of the shaft. [2 marks] Note: tasks i) to iii) can be completed just by drawing of one hand sketch without dimensions. (d) Calculate the life of the cylindrical roller bearing in hours after finding its reaction loads and its location in sections (a) and (c) respectively. The basic dynamic load rating of the selected bearing is C=28.5kN when the reliability of 95% is targeted. [3 marks]