Question 304Steam Plants - 1st Asst/Chief

The correct answer is C) Insufficient bearing crush. The key factor here is the need for adequate bearing crush, which is the compression of the bearing insert against the housing. Insufficient bearing crush can allow the split-type, precision insert bearing to rotate with the journal, causing the dowel or locking lip to shear. This is because the lack of proper compression prevents the bearing from being securely held in place, leading to the potential for movement and failure. The other options are incorrect because they do not directly relate to the root cause of the bearing failure. Unequal torque on the bearing bolts, short periods of above normal speed, and excessive bolt torque may contribute to other bearing issues, but they do not specifically cause the shearing of the dowel or locking lip due to insufficient bearing crush.