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).
Description of the Humfrey-Sandberg easy gear change unit.
| Identifier | ExFiles\Box 128\2\ scan0016 | |
| Date | 30th January 1931 guessed | |
| X2208. Associated Transmissions Ltd. 40, Grosvenor Gardens, London, S.W.1 DESCRIPTION of THE HUMFREY-SANDBERG EASY GEAR CHANGE UNIT. This arrangement of Humfrey-Sandberg Clutches (to be placed in a casing attached behind the gearbox, or preferably cast as part of it) is so disposed that the Clutches will perform the following functions :- The vehicle can be driven either free wheel or fixed wheel, but in both cases the method and ease of gear change is the same, i.e., fully declutching the main clutch and then moving the gear lever into the required notch without any necessity to consider either car or engine speeds. When driving free wheel, gear changes can be made, if desired, without declutching at all, although quicker changes can always be made by using the clutch. Two clutches are embodied in the unit, working in opposite directions. The clutch which transmits the forward drive is left permanently in engagement, but, of course, can over-run when the speed of the vehicle exceeds that of the main gearbox shaft. The second clutch transmits drive either when reversing or for allowing the vehicle to drive the engine when it is required to use the latter as a brake. When driving with this reverse clutch in engagement (i.e. fixed wheel) controls are arranged so that when the main clutch pedal is depressed it also withdraws the reverse clutch, and the gearbox is freed from the road wheels. The gear change is then made silently and quickly with the whole gearbox practically at rest, | ||