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).
Troubleshooting issues with gearbox synchronisation, gear crashing, and sticking cones.
| Identifier | ExFiles\Box 15\5\ Scan269 | |
| Date | 25th April 1932 | |
| -3- HS{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}13/A.25.4.32.contd. A 30° cam angle did not make the first part of the gear lever movement any easier but it became too easy to crash the gears before the speeds had synchronised. The reason we think that the pair of cones not operating offer a drag preventing the synchronising of the other two is that with the gear lever in neutral and the back of the car jacked up, the rear wheels commence to rotate and require a couple of several lbs. ft. to stop them. We therefore arranged so that the bronze cone should have to move .150 instead of .075 before engaging. With the oil in the gearbox hot there was no drag on the back wheels and the gear changing was slightly improved. A further trouble we have just found with this box is that on coasting to rest with the gear lever in neutral the sliding piece moves partially into top gear after which the interlock prevents further movement of the gear lever. The explanation of this is we think as follows. When running in top gear the top gear cones remain engaged, on moving the sliding piece into neutral the cones should also return to the neutral position due to the action of the synchromesh plungers in their grooves. If however due to expansion the cones seize together then instead of the sliding piece being able to disengage and centralise them it will be pulled by the action of the plungers partially into top gear, since the action of these 6 springs is stronger than that of the selector springs. This is further evidence of the way that the large dia: 7.11 cones stick, a thing we must prevent. HS{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} | ||