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).
Chassis alteration number 4, detailing modifications to the clutch brake spring to address slow gear changes.
| Identifier | ExFiles\Box 74\2\ scan0220 | |
| Date | 21th January 1929 | |
| X4194 cc - Mr. Beaver Mr. Burton OYS.R.1.21.29 Mr. A.F. Sidgreaves, Rolls Royce Limited, London, England. Dear Mr. Sidgreaves: January 21st, 1929. cc - Mr. F.H. Royce Derby Works Report on Chassis Alteration. No. 4 Section 6000 - Clutch Brake. Drawings - G 72600 M 12516 M 12542 Cause for Alteration. Numerous complaints have been received of the slow handling of cars in traffic due to the time taken to change speeds. The original clutch brake spring was 11 lbs. This was entirely too slow in stopping the clutch. The spring was increased to 30 lbs. The shift was still too slow. The spring was then increased experimentally to 65 lbs. This was much better but the time taken to stop was variable. Many clutches were dismantled after varying mileage and it was found that the oil from the clutch throwout bearing worked on to the clutch brake fabric, and was not dissipated. For perhaps a month after initial assembly or overhaul the clutch brake worked excellently (in fact with the 65 lb. spring it was too quick). After this, as the fabric became saturated with oil, the shift became gradually slower and slower. The 65 lb. spring gave good shifting under these conditions but it appears to us to be excessive in the load on the pilot bearing. We have fitted some of these springs in cars to satisfy owners however and the reports are favorable. -continued- | ||