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).
Outstanding questions regarding the design of Wraith brakes, specifically shoe and drum options.
| Identifier | ExFiles\Box 7\7\ X 606 Brakes-page004 | |
| Date | 27th March 1936 | |
| To E.{Mr Elliott - Chief Engineer} C. to Da.{Bernard Day - Chassis Design} c. to Hdy.{William Hardy} HH/AEL.10/JH. 27.3.36. Wraith Brakes. There seem to be two outstanding questions to be decided before work can be started on the above. They are :- (a) Whether we should use one or two pairs of shoes in the rear brake drums. (b) Whether to design the brakes for use with aluminium drums or cast iron drums. The following information may help you to come to a decision. (a) Some time ago we altered 3-S-IV so that hand and foot brakes operated the same shoes in the rear drums. The latter were very rigid, their diameter being 12"; the hand brake overall ratio was 52 and its linkage was more spongy than the foot brake linkage. We never had any trouble with this layout although we repeatedly used the servo to assist us apply the hand brakes. We think that the secret of the success of this system lay in the freedom from sponge in the foot brake system. If Wraith has a hand brake with 10.5" travel and overall ratio of 60 it will require adjustment less soon, not sooner, that the footbrake with an overall ratio of 23. It would be necessary with only one set of rear shoes to use either :- (1) a single stop on the foot brake linkage between the junction of direct and servo linkage and the rear equalizer, to prevent further travel of the | ||