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).
With suggestions for improving the epicyclic third-speed gearbox.
| Identifier | ExFiles\Box 178\3\ img051 | |
| Date | 29th January 1932 | |
| HS.{Lord Ernest Hives - Chair} ) FROM DA.{Bernard Day - Chassis Design} DY.{F R Danby} ) Copy to E.{Mr Elliott - Chief Engineer} EPICYCLIC 3rd. SPEED BOX. X7310. X7360. One of the suggestions is to increase the force of the spring working the ratchet. We understand that you have done this: we suggest that it should be doubled. It is also suggested that we should increase the strength of the main springs operating the brake. These give twice engine torque at .1 coefficient. We suggest that they should be increased 50%, if necessary using square wire, and tried. With reference to the clutch these springs can also be increased say 50%. We understand that you removed one plate and found that the slipping was appreciably worse. This would have the effect of reducing the strength of the springs as well as the number of plates. We have not previously seen GL.{G. Linnett}521., and on looking into it we see that slight alterations have been made in the position of the components of the brake operating gear, which have had the effect of reducing the reserve clearance after the brake is fully on - that is to say - when the clearance has been taken up and not allowing for any spring in the levers, stretch in the bands, or compression in the fabric, there is a matter of .225 reserve clearance before the lever is resting on the end of the slot in the connecting rod. If this happens it would immediately begin to relieve the spring load. On the original N. scheme we had provided for about .450 of reserve clearance. In order to improve this we suggest that the number of teeth in the ratchet should be increased from say 16 to 20, or better still 24. This would have the effect of reducing the band clearance around the drum, but as it is already more than we intended due to the position of the fulcrum of the lever which conveys the movement of the brake operating lever to the ratchet, we think no harm would be done in reducing it slightly. This should have the effect of causing the lever to stabilise in a higher position than shewn on GL.{G. Linnett} 521. Another suggestion which we presume would only be done after some of the less extensive modifications have been tried would be to increase the length of the crank which operates the (1) | ||