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).
Design and modifications for servo-assisted front and rear brake systems for different chassis models.
| Identifier | WestWitteringFiles\K\December1923\ Scan16 | |
| Date | 10th December 1923 | |
| TO DA.{Bernard Day - Chassis Design} FROM H.{Arthur M. Hanbury - Head Complaints} c. to ED.{J. L. Edwards} MR.RS.{Sir Henry Royce's Secretary} [Handwritten note]: work by ORIGINAL SECRET. RE BRAKES. E.{Mr Elliott - Chief Engineer} A.{Mr Adams} C. 111. These are to go ahead as originally arranged with only the certain modifications necessary to make them work passably. The front wheel braking will be kept very moderate in effect in such a way that with all the variations we can find the back wheels will always skid first. The epicyclic proportion we understand is now fairly satisfactory, the servo may require rather shorter shoes so as to be more consistent, the work thrown on this will be made as small as possible by modification to the back brake shoes so that they will be effective forwards with a small rope pull; backward efficiency in this scheme is of no importance. The front shoes must be fairly efficient forwards and very efficient backwards. HS.{Lord Ernest Hives - Chair} has all the necessary information except perhaps that he will require the design of some hinged shoes for the standard rear brakes, but we are not doing anything with these until the experiments with the 3 sets of front shoes are completed. E.{Mr Elliott - Chief Engineer} A.{Mr Adams} C. 1. & 11. The brakes on these chassis are to be alike, the servo is on the 4 speed gearbox carried by the engine, it is to be driven at one twentieth engine speed, (slow speed) is to be of the single plate type (special patent cooling) with ratchet drive (sliding patent worm). The speed of the servo is accelerated by the foot and the whole foot energy - 500 lbs per 100 lbs - is transmitted to and through the servo (assisting it and being available backwards) to the main servo pull of possibly 2000 lbs total (being about 500 lbs. through 4") available for all four wheels. This pull is divided (in about 10 to 4 ratio) by the latest (lever patent type) distributor. This should give an exactly constant proportionate brake rope pull between the front and back wheels. These two separate pulls are afterwards divided equally by the standard bevel equalisers between the wheels on each side of the car. If then the brake shoes and drums are in equal condition there should always be exactly proportionate braking between front and back, and equal braking on each side of the car, independent of variations in the servo or earlier part of the system. The brakes themselves and their shoes will be the same as in EAC.111. except that there will be a stouter shaft passing through the crankchamber so that only a short operating shaft will be on each side of the front axles. (1) | ||