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).
Notes discussing problems and solutions for brake drum liners, including doweling, crackling, and thermal expansion.
| Identifier | ExFiles\Box 159\5\ scan0090 | |
| Date | 5th November 1940 | |
| Cont'd.{John DeLooze - Company Secretary} - 3 - 10. We thought we could dowel liners in position. [This sentence is struck through] No dowel yet conceived by R.R. has been satisfactory. Either liners stay put by shrink fit or not at all. [Notes associated with diagrams A and B] Fiendishly expensive. Cannot be locked. Breaks smooth surface of drum. No dowels now used. Much cheaper. Looks alright but if called upon to take torque promptly breaks liner in corner. (Handwritten text: Part of LINER, KEY) 11. Crackling. We never solved this trouble. It appears to be due to axial movement of liner relative to case. The dowels type A.{Mr Adams} seemed fairly good but too expensive. We noticed the surface of the liner next the aluminium corroded resulting in bad temperature grade. Plating was introduced to stop this. Dowel on 'open' side of drum caused weakness and failure of case. Liner could be made in series of rings - never tried. 12. Circumferential looseness does not seem to be a worry so long as the liner cannot come out sideways. I have known a drum with quite a loose liner work satisfactorily for many miles, until it came out sideways. 13. On cars, we made drums so that on the "red gate" or other test run, max: temp: was 100 deg. C. I think this is rather important. If you exceed it, watch out for trouble. We tested them on the rig up to 200 deg. C. 14. There is every reason to suppose that when the brakes are in use the liner runs hotter than the aluminium, due to temperature grade. Rapidly equalises on releasing brakes. | ||