Question

PROBLEM 2 and 3 (journal bearing) A gear-reduction unit uses the countershaft depicted in the figurel. The reactions at bearing positions and C, are shown in figure 2. Note that only bearing position take the axial load. The bearing at position is to be angular-contact ball bearings, having a desired life of 50 kh when used at 300 rev/min. Use 1.2 for the application factor and a reliability goal for the bearing pair of 0.96, assuming distribution data from manufacturer 2 in Table 11-6. Select the bearings from Table 11-2. Tables on the pdf provided in class. At position C, a full journal bearing is selected, the shaft diameter is 30.00 mm, with a unilateral tolerance of -0.012 mm. The bushing bore has a diameter of 30.05 mm and a unilateral tolerance of 0.032 mm. The bearing is 30 mm long. The journal load reactions are on figure 2, and it runs at a speed of 300 rev/min, using an average viscosity of 55 mPa. S, find the minimum film thickness, the aximum film pressure, and the total oil-flow rate for the minimum clearance assembly Comment on your modifications to improve the design of the gear box Gece G 15 - 150 75 9. ---- 10 OSO Figuere 1. Shaft, all dimensions in mm. 494 N 10337N 20673 N 10830 N 4350B 300C 300 I 5 5083 N 3762 N 9640 N 8319 N Y B O 2823 N 2823 N Axial force distribution Figure 2. Reactions at position and C. planes X-Y and X-Z. Reaction in Newton. Axial load

Answer 1

Solution → Journal Begaina LP 1 200, 73N' 0 5083 design in Journal d= 30mm -given p=w - 4599 0:1476_N/mm 1080X30 Ratio LA 1080 mm 080 36 $ 21 - 2.1 55 X 300 30 = 11652-5 1.416 free calculation, k4940 AX 8762 108-30P 10337-N Ibyon 8319 N. 6573 (400) I 19149 N 380 mm 30313 N Mo 40.4) X 6675 + 0.75 ( 30313) - 1.08 X9149 -1.71m ffeat generation Hg = MW.V u= 33.25 - (287) 33.25 35X300 30 f00002 -3 0.1416 100X10 4 = 0.118234 s W = 4589 H VetTDN TI ( 30x103) (300) 0.47 m/s 60 300 mm Toto 4589 N X X 1010 1010 60 Mg-0.118234X 4589 x 0.47 - 253,6826. minimum clearance 100x10= 0.025 4 4 The maximum beaning pressure can be obtained transmission shaft :P6= 1.05 N N/mm2. Assumptian