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).
Tests conducted on rear wheel foot brakes, noting issues with heat, expansion, and permanent distortion.
| Identifier | ExFiles\Box 26\4\ Scan045 | |
| Date | 17th August 1914 | |
| From Exp. Dept. Copies for: J.{Mr Johnson W.M.} R.{Sir Henry Royce} Hy.{Tom Haldenby - Plant Engineer} Ha. REPORT ON REAR WHEEL FOOT BRAKES. We commenced to carry out a series of tests similar to those which I reported on under ref. Wor{Arthur Wormald - General Works Manager}/Hy{Tom Haldenby - Plant Engineer}9/L14814 but using the ribbed brake drums 2" wide instead of those 1¾" wide. The brake straps were 1½" wide but were fitted with 2" Ferodo liners. The effective pressure surface was therefore only 1½" wide. We ran a test on 3rd gear at 20 M.P.H. on bumping machine drums, full throttle, the power absorbed being 39 HP. After running 6 minutes the near side brake became red hot and this without the pedal lowering more than about ¼". This shows that the brake straps were expanding and following the drum outwards. The brake drum and parts of the brake straps were bright red when we stopped. On examination we found that some of the copper rivets were flush with the friction surface and these were evidently conducting the heat from the drum to the straps causing the expansion of the two parts to be almost equal. The brake straps were only red hot at the points where the rivets were in actual contact with the brake drum and these parts are shown shaded on the sketch. When cooled down the straps were found to be permanently distorted, the amount of distortion being shown on the sketch. X.Y.9. | ||