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).
Calculations for the helix angle and overlap of Bensport timing gears.
| Identifier | ExFiles\Box 136\1\ scan0081 | |
| Date | 30th August 1933 | |
| X 411 FILES. 30.8.33. BENSPORT TIMING GEARS. HELIX ANGLE & OVERLAP. STANDARD GEARS 16.75 D.P. Width of gears on pitch line = 0.97" Helix angle = 35° Let x = length of arc subtended by 1 tooth. x = 0.97 tan. 35° = 0.680" Circular pitch of gears = 0.229" Overlap = 0.680 / 0.229 = 2.97 pitches. SPECIAL GEARS WITH FABROIL CAMWHEEL 10.D.P. AS FITTED TO B.5. UNIT. Width of gears on pitch line = 0.91" Helix angle = 39.5°. Circular pitch 0.407" x = 0.91 tan. 39.5 = 0.751 Overlap = 0.751 / 0.407 = 1.845 pitches. For overlap to be equal to that of standard gears = 2.97 x = 2.97 x 0.407 = 1.208" Tan. (Helix angle) = 1.208 / 0.91 = 1.327 Helix angle must be 53° Hs{Lord Ernest Hives - Chair}/F.J.Hardy. | ||