A 16 tooth pinion drives a double reduction spur gear train, as shown. All gears have 25 ° pressure angles. The pinion rotates counterclockwise at 1,200 rpm and transmits power to the gear train. The tree is not designed yet, but the free-body diagrams have been generated, as shown in the figure. Tree speeds are 1,200 rpm, 240 rpm, and 80 rpm. Forces are represented in pounds
The study of a bearing begins with a life of 10 kh and a reliability of the assembly of the 6 bearings of 0.99. An application factor of 1.2 is adequate. Specify the six CYLINDRICAL bearings
a). Assuming that all six bearings have the same reliability, determine the expected load capacity and type of 02 series bearing specified in Table 11-3, for bracket E.

b). If the expected reliability of bearing E is 90%, what would be the load capacity and what would be the selected bearing from series 02

c). With the load capacity obtained with the formula in the previous paragraph and the internal diameter obtained from Table 11-3, specify a bearing from the SKF page that meets the minimum requirements (look for the bearing with the diameter obtained and the capacity of immediate superior charge of subsection (b)). What is the new load capacity and catalog number of the selected bearing?

d). With the information in part (c) determine the expected life of the bearing in hours and in millions of cycles.

e). The setting to be used in the bearing assembly is j6 for the shaft and P6 for the housing. Determine the tolerances of the bearings and their respective shafts and housings and identify the interferences or maximum clearances in both cases. Make a schematic drawing of the assembly showing the nominal diameters and their tolerances.

 

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