Examination of Wraith brakes, detailing pedal pressures under various conditions and emergency functionality.
| Identifier | ExFiles\Box 7\7\ X 606 Brakes-page055 | |
| Date | 4th May 1937 | |
| SECRET. 606. E. {Mr Elliott - Chief Engineer} from Rm {William Robotham - Chief Engineer} /AFM. {Anthony F. Martindale} Hs. {Lord Ernest Hives - Chair} Da. {Bernard Day - Chassis Design} Ry. Hdy. {William Hardy} Ev. {Ivan Evernden - coachwork} ____________ Rm {William Robotham - Chief Engineer} /AFM {Anthony F. Martindale} /R.4.5.37. WRAITH BRAKES. We have examined the brakes on 25.G.VI, and we consider them to be fairly satisfactory, now the servo is working. The following table gives the pedal pressures for various conditions. Pedal Pressure lbs. 100 approx. Locks rear wheels, rough dry surface. 90 " " " wet " 35 Takes up shoe clearance servo stationary with present 15 lb pull off springs on bell cranks. 15-20 Takes up shoe clearance, no springs on bell cranks. 25-30 Takes up shoe clearance, 3-5 lb springs on bell cranks. 15-18 Takes up shoe clearance, servo running, present pull off springs. We have suggested that W.Sch.5117 should show 4 lbs low rating pull off springs on the bell cranks in the rear brake linkage. Emergency brakes after a failure. With both rear brakes disconnected and the servo stop on the point of coming into operation, the front brakes still work. The brakes come on immediately the servo has wound up without the need for groping for the hand brake; the braking is reasonably effective, the car quite controllable. The front wheels can be locked. We drove two miles like this without any discomfort. The front brakes smoked. | ||
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).