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).
The cable drum diameters and gear ratios for a launching winch.
| Identifier | ExFiles\Box 175\2\ img131 | |
| Date | 21th May 1941 | |
| To Rn.{Mr Robinson} From DV/DD. SECRET. LAUNCHING WINCH. Cable Drum Diameters and Gear Ratios. It has been agreed to supply a range of drum diameters and gear ratios with the launching winch. From conversation with members of the C.L.B. Ringway, staff who visited us here, it appeared that they were anxious to obtain a fairly high speed early in the launch, and were also anxious that the pull available towards the end of the launch should not be unduly diminished. This suggested that we should employ a larger and longer drum than originally intended. The two diameters chosen are 10" and 12" and the length has been increased to 22 1/2" between the flanges instead of the original 20" giving 61 turns/layer instead of 72. WINCH DRUM DIAS AND GEAR RATIOS Three gear ratios are suggested and these can be obtained by alterations in the gears only, the casing being arranged to take the largest gears of the set; the gear centre distances remain unaltered. The gears required and the resulting ratios are set out in the table below :- | Pinion | Gear | Idler | Ratio | |---|---|---|---| | 40 | 89 | 74 | 2.225 | | 32 | 81 | 82 | 2.53 | | 25 | 74 | 89 | 2.96 | It is probable that the combination of the 10" drum and 2.96 gear ratio will not be useful as it gives a maximum cable speed of 70 m.p.h. only at 4000 engine r.p.m. Two graphs have been prepared to show the cable pulls and speeds obtainable with the various Cont'd.{John DeLooze - Company Secretary} | ||