Question

5) An eight-cylinder diesel engine has a front main bearing with a journal diameter of 3.500 in and a unilateral tolerance of 20.003 in. The bushing bore diameter is 3.505

in with a unilateral tolerance of10.005 in. The bushing length is 2 in. The pressure-fed bearing has a central annular groove 0.250 in wide. The SAE 30 oil comes from a sump at 120°F using a supply pressure of 50 psig. The sump's heat-dissipation capacity is 5000 Btu/h per bearing. For a minimum radial clearance, a speed of 2000rev/min, and a radial load of 4600 lbf. Find the average film temperature and apply Trumpler's criteria in your design assessment. (10pts). Repeat this scenario 3 times with different grade SAE oil, different supply pressure and different speed while all are held the same. What can you conclude by changing these parameters and how does that effect the design? (10pts).

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