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).
Specifications for belt and pulley angles on B.60 and B.80 engines.
| Identifier | ExFiles\Box 135\4\ scan0027 | |
| Date | 25th May 1939 | |
| 1135 & 10HH To By/CS. Rm{William Robotham - Chief Engineer}/Ed.{J. L. Edwards}17/JH.25.5.39. B.60 & B.80 Pulleys. We have been over the belt and pulley angles on the above engines, and find that these should be as under, dimensions being taken from an actual belt bent to conform to the pulley diameter. B.80. Crankshaft. Pulley angle 36°, top width .900". Depth. .500". Fan. 5.6875" dia. Pulley angle 34°, top width .900". Depth .500". Dynamo. 4.175" diam. Pulley angle 33°, top width .900". Depth .500". B.60. Fan. 6.25" diam. Pulley angle 31°, top width .625". Depth .450". Crankshaft. 5.625" diam. Pulley angle 29°, top width .625". Depth .450". Water Pump. 4.00" diam. Pulley angle 28°, top width .625". Depth .450". | ||