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 approximate helix angle of 'La Salle' and 'Marles Type L.7' steering gears.
| Identifier | ExFiles\Box 28\3\ Scan058 | |
| Date | 15th November 1934 | |
| APPROXIMATE HELIX ANGLE OF STEERING GEARS. 'LA{L. A. Archer} SALLE ESTIMATED DIMENSIONS OF GEAR RATIO 20:1 HELIX ANGLE = tan⁻¹ (1.625 x 2) / (1.250 x 20) = tan⁻¹ 0.130 = 7.4° MARLES TYPE L.7 DIMENSIONS SCALED FROM PRINT. ORIGINAL RATIO 15:1 HELIX ANGLE = tan⁻¹ (2.240 x 2) / (1.460 x 15) = tan⁻¹ 0.205 = 11.5° PRESENT RATIO 17:1 HELIX ANGLE = tan⁻¹ (2.240 x 2) / (1.460 x 17) = tan⁻¹ 0.180 = 10.2° H.F.H. 15/11/34 | ||