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).
Trials on steel brake shoes, discussing issues of clearance, seizing, and permanent growth compared to aluminium shoes.
| Identifier | ExFiles\Box 102\3\ scan0111 | |
| Date | 5th February 1934 | |
| X 5360 To Sg.{Arthur F. Sidgreaves - MD} From Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} c. to Wor.{Arthur Wormald - General Works Manager} c. to Sy. c. to Da.{Bernard Day - Chassis Design} c. to Hdy.{William Hardy} Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}23/KW.5.2.34. Steel Brake Shoes. We have tried steel brake shoes on the rear brakes of both 18-G-IV and 19-G-IV, on the front of 28-EX, and on all the brakes on both 2-B-IV and 3-B-IV. On the 20/25 we find that the brake clearance can be reduced from .750 to .500 without seizing. At 1" clearance however the pedal reaches the floorboards after a few miles of hard driving owing to the shoe expansion not following the drum expansion. On 3-B-IV we lost a pedal travel equivalent to 3 half turns of the wing nut adjustment in one descent of Porlock hill. The reason we have experimented with steel shoes is primarily to overcome the trouble of rear brake seizures on the 20/25. In several cases of brake seizure JLE.{J. Lee Evans - Chassis Test Manager} told us that the brake clearance had decreased, pointing to the shoe having increased permanently in size. We confirmed this on one of our own cars and also by heating a 40/50 shoe after which it had taken a permanent set. Hy.{Tom Haldenby - Plant Engineer} has therefore arranged for all brake shoes to be heat treated on production so that further permanent growth will not take place. 28-EX 10,000 miles car is to have the wider front brake drums. Built up steel shoes have also been instructed. We consider that aluminium shoes would be preferable and have asked Hy.{Tom Haldenby - Plant Engineer} to issue details of a wider aluminium shoe. The built up steel shoes are not easy to make and we cannot see that they would be any advantage on the front of the 40/50 where there are no complaints of seizing. There will be the disadvantage of the servo reaching its stop earlier than with aluminium shoes. Hs{Lord Ernest Hives - Chair}/H.{Arthur M. Hanbury - Head Complaints} Grylls. | ||