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 to Templewood Engineering Co., Ltd. discussing issues with aluminium brake drums and potential solutions.
| Identifier | ExFiles\Box 170\1\ img038 | |
| Date | 1st November 1938 | |
| 1028 Rm{William Robotham - Chief Engineer}/APM1/R.{Sir Henry Royce} 1st November, 1938. Templewood Engineering Co.,Ltd., 490, Ipswich Road, Trading Estate, SLOUGH, Bucks. (For the attention of S.S. Tresilian, Esq.) Dear Sirs, We understand that you are prepared to make two or three sets of aluminium brake drums, and pay for the experimental charges in connection with same. Our interest, therefore, is only that drums submitted for test are likely to have sufficient endurance - if they have not then delay in standardisation will occur. Our own aluminium drums have only one technical fault; they emit a noise generally called "contraction crackles" although in reality it is due to rapid expansion of the liner, and relative movement between liner and drum parallel to the axis of the drum cylinder. We have had one or two liners shift sideways, when subjected to severe overloads, but under the same treatment we crack iron drums of the same volume so this can not be said to be a weakness peculiar to the aluminium drum. We think your solder should help in both these cases. We have had various other troubles but they have been overcome; the one we will not tolerate is failure of the aluminium casing. Our cases fail unless we use a cast iron liner .100 thick; if the liner is made of steel (Youngs modulus 30 x 10⁶) the cases crack; if we use a low carbon iron (semi-steel, E = 18 x 10⁶) the liners come loose but if we use an ordinary cast iron (3.25% carbon) then the drums are satisfactory. You will see there is very little margin so your intention of using a thicker liner may lead to trouble unless you use a lower interference and make use of the adhesive properties of your solder to keep the liner in place. | ||