Soal#2

Tryout UJIAN TENGAH SEMESTER 1. A journal bearing has an L/D ratio of 1, a 3-in. diameter, an oil viscosity 4 × 10-6 reyns, and an r/c ratio of 1000. A minimum film thickness of 0.0006 in. is to be maintained and the rotative speed is 3000 rpm. Determine the following quantities for a 120-deg bearing, (a) Flow entering in cubic inches per second. (b) End leakage in cubic inches per second. (c) Load. (d) Coefficient of friction. (e) Frictional horsepower. (f) Temperature rise of the oil.

2. For a 60-mm single-row deep-groove ball bearing of dimension series 02, Table 9.1 lists the following values for the basic dynamic and static load ratings as C = 9070 lb, and C0 = 6950 lb. This bearing to be used to support a shaft with stationary center load of 2000 lb. and stationary thrust load of 300 lb. If the speed of shaft is constant at 1000 rpm, determine: (a) the L10 rating life in revolutions and hours for this bearing. (b) the median life in hours for this bearing. (c) the expected life of this bearing if equivalent load were increased by 50%. (d) the equivalent load for this bearing if operation life were increased 100% above the L10 rating life. (e) the basic number of this bearing that one finds listed in industrial catalogs.