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).
Extract detailing calculations for drum and shoe sizes for Lockheed Hydraulic Brakes on the MYTH vehicle.
| Identifier | ExFiles\Box 110\1\ scan0009 | |
| Date | 13th September 1940 | |
| 1030 706 EXTRACT FROM Ev{Ivan Evernden - coachwork}4/JH.13.9.40 re Lockheed Hydraulic Brakes. .................. .................. MYTH. It was agreed that MYTH should have the same hydraulic equipment as Rippletto and the same pipe line pressure. The difference in weights being provided for in the diameter of the drum, and the width of the shoes. The calculation to arrive at the drum size is as follows:- Car loaded 26 Cwts, or 2900 lbs, 5.5 x 16 Tyres, Rolling radius 13" Retardation per wheel 750 lbs approx: Shoe tip pressure assuming 7/8" diam: wheel cylinder 550 lbs. Retardation at drum 2200 lbs. This gives the drum approximately 8.9" diam: Mr Parnell stated that he recommended the standard 9" drum with 1.5" wide shoes, the drum diameter being slightly increased to accommodate the thicker lining. Mr Parnell will investigate the use of the plate lever hand-brake operation, but it was tentatively agreed on his recommendation that we should use the latest bisector. .................. .................. Ev.{Ivan Evernden - coachwork} | ||