From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Bearing materials, lubrication, fitting, and clearance specifications.
| Identifier | ExFiles\Box 115\5\ scan0047 | |
| Date | 27th May 1938 guessed | |
| 1. to corrosion as a bearing in contact with oil; this is known to occur with Cadmium and Lead Bronze. The Brinell hardness is only slightly reduced when at 150°C. whereas normal Babbit metal falls for 30 Br.{T. E. Bellringer - Repair Manager} in the cold to about 5.Br. at 150°C. Concerning lubrication etc., we will requote an extract from Messrs. Rolls Royce Technical Information - "We have found that lubrication plays a tremendously important part in successful bearing operation, and to great a care cannot be taken in establishing a sufficient oil supply; this particularly applies to bearings for use in high speed high performance engine where explosion and inertia loads can be very high." Interference Fit. We recommend that bearings are fitted with their outside diameter greater than the diameter of the housing into which it fits. The figure we usually work to is 0.0005/inch diameter. Nip of Bearings in Housing. By nip of bearing, we mean the amount by which the bearing halves stand proud of the joint face. This should be 0.001" on each side of the bearing relative to the joint face for each half of bearing. Working Clearance. We recommend the following clearances for bearings. (a) CONNECTING ROD BEARINGS. For connecting rods we find the following clearances satisfactory - Minimum - 0.001/inch diameter. Maximum - 0.0012/inch diameter. (b) Main Bearings. For main bearings where crankcase and crankshaft distortion must be taken into account, we find that the following clearances are necessary - Minimum - 0.0012/inch diameter. Maximum - 0.00155/inch diameter. Preferred - 0.00125/inch diameter. | ||