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).
Winch drum diameters and suggested gear ratios, including performance calculations.
| Identifier | ExFiles\Box 175\2\ img125 | |
| Date | 5th June 1941 guessed | |
| -3- Winch Drum Dias. & 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 | 69 | 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 drum sizes and gear ratios. In order to make the picture as easy to follow as possible the graphs of cable speed and pull are plotted on a base of distance run from the commencement of the Launch. It will be noticed that we have catered for approx. 4500/ft. of cable, this being the figure the C.L.E. people said they would like and more than their official minimum of 3500 ft. The initial part of the graph is based on the full engine speed of 4000 r.p.m. being attained in the first layer of cable (less some 9 turns left on permanently for cable attachment and adhesion). If this condition is not fulfilled the commencement of the main part of the curves of pull and speed will occur rather further over to the right. As an example of what this means, with the 10" drum and 2.96 ratio a weight of towed object plus cable of 7220 lbs. can be accelerated to 4000 engine r.p.m. in the first layer of cable, and with the 12" drum and 2.225 ratio the corresponding figure of 2180 lbs. The weight of 4500 ft. of cable is about 550 lbs. Cont'd.{John DeLooze - Company Secretary} | ||