Journal bearings provide radial support for the rotating equipment and thrust bearings provide axial positioning for them. Ball and roller bearings are used in some aircraft jet engines. However, all industrial gas turbines use journal bearings.
Journal bearings can be split or full-round. Large-size bearings used for heavy machinery normally have heavy lining. Precision insert-type bearings used commonly in internal combustion engines have a thin lining. The majority of sleeve bearings are of the split type for convenience in maintenance and replacement. Figure 16.1 provides a comparison of different types of journal bearings. The following is a description of the most common types of journal bearings:
Plain journal. The bearing is bored with equal amounts of clearance between 1.5 10 ? 3 in (3.8 10 ? 3 cm) and 2 10 ? 3 in (5 10 ? 3 cm) per inch of journal diameter between the journal (portion of the shaft inside the bearing) and the bearing.
Circumferential grooved. This bearing has the oil groove at half the bearing length. This design provides better cooling. However, it reduces the load capacity by dividing the bearing into two parts.
Cylindrical bore. This bearing type is commonly used in turbines. It has a split design. The two axial oil-feed grooves are at the split.
Pressure or pressure dam. This is a plain journal bearing with a pressure pocket in the unloaded...
TABLE OF CONTENTS 
