Letter from The Rover Company to Rolls-Royce detailing specifics on brake wedge angles and pull-off springs.
| Identifier | ExFiles\Box 120\3\ scan0096 | |
| Date | 13th November 1934 | |
| - 2 - Messrs. Rolls-Royce Ltd. 13th. Nov. 1934. if it was ever found necessary, from the point of view of this wedge indentation, the core hardness of these pieces could be very materially improved. (2) Wedge Angle. We are using 18° included angle on the wedge, and have not much experience of angles of more than 1° or 2° on either side of this figure, all of which were entirely satisfactory. (3) Pull-off spring. We use a pull-off spring having a tension, with the brake off, of 50-lbs, (see enclosed sketch), at the rollers between the shoe ends. We make a special point of keeping this spring pressure as light as possible for ease of brake operation, so we probably err on the light side, if anything. The tension required would, of course, depend very much on the amount and type of "works" that have to be operated between the brake pedal and the shoes. (4) We are not quite sure whether this question refers to a flat sided wedge or the conical one, such as we use. We have not had any practical experience with a flat sided wedge, having turned this type down in the early stages, as it would seem that, due to the shoes pivoting, there could never be more than point contact with the rollers, excepting in one critical position. You will see from the wedge we are sending that the alteration in contact position with a fair amount of shoe adjustment (which has taken place on the car in question) is very slight. We have never been able to detect any difference in brake operation, due to adjusting, from this cause. Will you please return the wedge when you have inspected it. Hoping this will provide the information you need. Yours sincerely, THE ROVER COMPANY LIMITED. M.C. Wilks Technical Department. | ||
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).