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).
Diagrams illustrating the conical pitch surfaces of bevel gears and the hyperboloid pitch surfaces of hypoid gears.
| Identifier | ExFiles\Box 114\1\ scan0092 | |
| Date | 11th January 1937 guessed | |
| Fig. 4 PITCH SURFACES FOR BEVEL GEARS ARE CONES Fig. 5 PITCH SURFACES FOR HYPOID GEARS ARE HYPERBOLOIDS OF REVOLUTION | ||