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).
Issues with brake drum flexibility and proposals for increased stiffness.
| Identifier | ExFiles\Box 120\1\ scan0023 | |
| Date | 26th November 1930 | |
| HS.{Lord Ernest Hives - Chair} } FROM R.{Sir Henry Royce} BY.{R.W. Bailey - Chief Engineer} } X4612 Rl/M26.11.30. C. to SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} BRAKE DRUMS. We telegraphed Derby today as follows: "BAILEY - STOP ALL BRAKE DRUMS PENDING INCREASED STIFFNESS". From Mr. Hancock's description of experience by the Crickle-wood Service it would appear that the chief trouble with the brakes is due to the drums being too flexible, that is, they are too easily pushed out of true circle. I believe that if we increase the stiffness we shall avoid a multitude of troubles. Most of the forms we can suggest would consist of a light drum with a liner. The drum could be aluminium sheet, or cast, or wrought steel sheet, and the liner could be cast iron, which is considered to provide the best surface, or naturally hard steel such as manganese steel which is used for tramway crossings. The alternative (which I prefer) is to use a ring which is made from a thick tube or forging and turned with radiating and stiffening rims, this being carried by sheet steel conical disc hub. This would probably be the best and give a simple means of attachment and easy replacement. The double flange will give great stiffness and some help to cooling. I will get Mr. Day to send through a set of drums of the type preferred by us for both cars, and both front and back axles. If these do not give satisfaction we must try some of the alter-natives. I think they will have marked influence on sponginess, loss of braking, and such troubles, and provide a comparatively inexpensive replacement scheme. The thin drums were adopted to prevent jaggers, by tests of the Expl. Dept. We are proposing a new type of shoe which should at least modify the squeaks for better or worse. It will be remembered that much stiffer drums were origin-ally supplied, but more is known about squeaks, jaggers, etc, and they may now be acceptable. It would appear that the flexibility of the brake drums results in wearing off the ends of the liners on the shoes. Then during light braking the middle of the liner only touches. In this condition squeaks are prevalent. (1) | ||