In the figure is a proposed shaft design to be used for the input shaft a in Prob. 7–7. A ball bearing is planned for the left bearing, and a cylindrical roller bearing for the right. (a) Determine the minimum fatigue factor of safety by evaluating at any critical locations. Use a fatigue failure criteria that is considered to be typical of the failure data, rather than one that is considered conservative. Also ensure that the shaft does not yield in the first load cycle.
(b) Check the design for adequacy with respect to deformation, according to the recommendations in Table 7–2.
In the double-reduction gear train shown, shaft a is driven by a motor attached by a flexible coupling attached to the overhang. The motor provides a torque of 2500 lbf · in at a speed of 1200 rpm. The gears have 20o pressure angles, with diameters shown on the figure. Use an AISI 1020 cold-drawn steel. Design one of the shafts (as specified by the instructor) with a design factor of 1.5 by performing the following tasks.
Problem 7–8
Shoulder fillets at bearing seat 0.030-in radius, others 1/8 -in radius, except right-hand bearing seat transition, 14 in. The material is 1030 HR. Keyways 38 in wide by
3/16 in deep. Dimensions in inches.
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