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 detailing the results of efficiency experiments on a submitted Girling brake sample.
| Identifier | ExFiles\Box 120\3\ scan0121 | |
| Date | 29th December 1934 | |
| 4456 Exptl. Dept. Hs{Lord Ernest Hives - Chair}/AFM.{Anthony F. Martindale}1/RW. 29th December, 1934. The New-Hudson Co.Ltd., St.{Capt. P. R. Strong} George's Works, Icknield Street, Birmingham 18. For the attention of Mr. Fraser. Dear Sirs, Re Girling Brake Sample submitted for Test. We have recently carried out several efficiency experiments on the sample brake submitted for test. During these tests an indicating clock was fitted to one shoe measuring the relative movement between the shoes in thousandths of an inch. A load of 300 lbs. over and above that required to overcome the pull off springs was applied to the operating rod, and the total "sponge" in one shoe at the cam centre was 27 thousandths. It is our custom here to have a clearance of 30 thousandths between shoe and drum at the point of maximum movement, i.e., opposite the toggle. With the "sponge" this makes a necessary movement of 57 thousandths for one shoe in order to get maximum braking. The maximum travel of one shoe that we were able to get with the brakes under load was 80 thousandths, and thus only 23 thousandths is available for wear before a drop in braking force would occur unless adjustment were made. The brake drum used was one of our standard Bentley brake drums, such as is fitted to the axle you have at present in your Works. | ||