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).
Advantages of the 'adopted' braking and servo scheme over competing systems.
| Identifier | Morton\M20.1\ img030 | |
| Date | 28th May 1924 | |
| COPY FROM R.{Sir Henry Royce} [redacted] SECRET. Copy to E.A.C. " [redacted] " H.S. " [redacted] E.A.C. 11. & 111. BRAKES ETC. Handwritten: x9940, x9770 x On the 6th inst. HS.{Lord Ernest Hives - Chair} brought us 4 cars, one being the Hispano. After spending the day on them we all agreed that any one of our 3 schemes was workable, but that the best combination was on the cabriolet No.2. which was fitted with RGs. plus RG{Mr Rowledge}'s second connecting rod for servo assistance backwards, as shewn in the sketch herewith, and known henceforth as the "adopted" scheme. This scheme has several distinct features in addition to Mr. Rowledge's back running device. It also appears very simple and clean and not at all difficult to understand or adjust. We believe it is the best combination that is being offered by anyone. We have the following advantages over most others:- (1) RG{Mr Rowledge}'s backward servo assistance enabling a lady to hold a heavy car backwards on a steep hill. (2) Considerably more direct braking by concentrating our direct foot pressure on the rear wheels only and with the proportions possible this braking appears to be 3 or 4 times more effective than the Hispano. This has the advantage of holding the car at close quarters during shunting etc on inclines, and therefore rendering the lag of RG{Mr Rowledge}'s scheme less harmful. (3) A servo, whose action depends directly upon the co-efficient of friction of the material, and is not susceptible to the bedding of lapping shoes, as in the case of the Hispano and self servoing brakes where the co-efficient of friction acts in some proportion greater than its first power. (4) A servo should not require adjusting for approximately 20,000 miles owing to its large surface, and to the fact of its large angle of operation requiring only a small torque. (heat and unit pressure which in our case is low governing life.) (5) The brakes themselves having the extra security of substantial steel drums and efficient actuating mechanism, so that although worn and neglected the brakes are not likely to stick on by the jamming of the cam, that is, although they may continue to rub when removed there will be no serious braking through being jammed on by an inefficient cam having arrived at its zenith. (6) Simple and efficient compensation of the action of the servo between the front and the back wheels by means of the floating lever, and not dependent upon the doubtful skill of the ordinary driver of adjusting the proportion of braking (1) | ||