This specification covers the requirements for castings, and is not intended for the purchase of ingots.

This specification covers grades of bearing bronze ranging from Grade V, which is soft and deformable to Grade PZI, which is hard and brittle. In respect to permissible loading per unit area of bearing surface, bearings of Grades V, I, IV, II and III, vary in the order stated, Grade V being suitable for the least, and Grade III for the greatest unit loads. Where lubrication is imperfect or not dependable, the permissible relative speed of the bearing surface for equal unit loadings varies in the reverse order, Grade V being suitable for the highest speeds.

Grades I, IV and V are suitable for bearing liners for operation under conditions such that the bearing metal is required t o deform locally to conform to irregularities of motion or imperfection of fitting. These grades also provide reasonable service where lubrication is fauttg. Bearing of railway rolling stock, travel- cranes, rock crushers, winches, and conveyers are examples of applications for which these grades are particularly suitable.

Grades II and IV are good bearing bronzes for general bearing surfaces, They are also reasonably good structural bronzes and are suitable materia1 for members in which the bearings are integral with the supporting or enclosing structure.

Grade III bronze is a hard bearing bronze, also known as hard gear bronze.

Grade VI bronze is suitable for use where strength, hardness, or shock resistance is required. It is suitable for heavily loaded, true running, finely finished bearings which are lubricated.

Grade VI1 bronze is used for torpedo engine and tail bushings.

Grade VI11 bronze is adaptable for pressure tight castings.