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).
Letter discussing issues and potential solutions for brake squeak and wear with Gandy's 'Safeguard' brake lining.
| Identifier | ExFiles\Box 140\4\ scan0126 | |
| Date | 5th January 1938 | |
| GANDY'S "SAFEGUARD" BRAKE LINING - CONTINUED MESSRS. ROLLS ROYCE LTD. (2) 5th January, 1938. On top of the normally severe working conditions this may lead to charring and consequent rapid wear, in the present instance, five times greater than normal. Although you would take care to adjust the Brake correctly, initially, it is very probable that the swelling of the Lining did not occur equally on all four assemblies and this would completely upset the distribution of Braking load. We will take precautions to eliminate this swelling, which is partly due to the presence of the graphite, in the case of any future samples which we send to you. Our impression is that had the brakes remained correctly balanced the squeak would not have occurred, certainly not after such a short distance as 100 miles. In our next experiment with graphited liners, we will put in the maximum amount where possible, in order to settle finally whether this line of experiment is likely to cure the squeak. We note that you have obtained good results with Ferodo MR/3, and we have some experiments in progress along the lines you suggest. In regard to further samples, we are sending, to-day, the following test pieces. (a.{Mr Adams}) Safeguard "D" for the leading shoe to be used in conjunction with standard Safeguard "400" on the trailing shoe, together with duplicates. Should your test rig squeak with this combination, we would suggest repeating the test with fresh samples, after drilling 6 holes 3/8" dia. through the working face of the brake drum, the holes being symmetrically disposed about the centre and being staggered across the width of the Brake path. We might repeat that this combination of Safeguard "D" with "400", in conjunction with the holes, permanently cured an extremely bad case of Brake Squeak. | ||