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).
Cumbersome gearbox on the Phantom III and proposing to test a Packard gearbox as a replacement.
| Identifier | ExFiles\Box 94\2\ scan0054 | |
| Date | 4th November 1936 | |
| 328 Hs.{Lord Ernest Hives - Chair} c. to E.{Mr Elliott - Chief Engineer} Da.{Bernard Day - Chassis Design} Hdy.{William Hardy} Rm{William Robotham - Chief Engineer}/Gry{Shadwell Grylls}2/OR.4.11.36. GEARBOX FOR P.III. There is no doubt that the operation of changing gear on P.III requires too much effort. There is also no doubt that the gearbox, as it is, is a very cumbersome, complicated, expensive and unsatisfactory way of altering the torque to the rear wheels. The addition of a relay mechanism, although it will lighten the operation, adds further complication and expense to hide an existing trouble. Sales pushed us into the synchromesh 2nd speed because certain cheap small cars had this feature. As the strength of the driver doesnot vary with the size of the car, the operation on our large cars is unduly heavy. It is far from light on the Hillman Minx. We see no justification for more than three speeds on the Phantom; we further think that synchromesh on the lowest gear is a very extravagant clutch stop. We have compared the merits of the twelve cylinder Packard box, which we know to be quieter than ours, with the P.III. If we made the Packard box in aluminium, we should expect to save about 40 lbs in weight, and at least one third of the present cost. The Packard synchromesh is one of the "non-positive" variety. Both Packard and Cadilac found this necessary on a large car. The car that Da.{Bernard Day - Chassis Design} and I tried in the States had a lighter operation than P.III, and could only be crashed with extreme violence. We recommend, and should like your agreement, obtaining a Packard box and fitting it to an experimental P.III car for criticism of the operation, and then the usual dynamometer testing. The interesting features of the Packard box are:- (1) Non-positive synchromesh operation in conjunction with 3 1/2° cones. (2) Side Shaft and gears integral necessitating pot-tapped unground gears. (3) Angular contact ball bearing mounting of the loose pinions in which slack cannot develop. | ||