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).
Water ingress into the B.V. & B.50 servo motor, detailing the causes and proposed solutions.
| Identifier | ExFiles\Box 152\2\ scan0240 | |
| Date | 30th January 1939 | |
| 1294 To By.{R.W. Bailey - Chief Engineer} _____ c. to Da.{Bernard Day - Chassis Design}_____ Rm{William Robotham - Chief Engineer}/JBD.{John B. Dixon - Fuel Systems}8/JH.30.1.39. B.V. & B.50. Servo. We have had cases of water getting into this servo and causing judders and groans during wet weather. Until, recently this trouble appeared to be cured by sealing the outside edge of the spring plate with adhesive tape or Heldite, this latter method has been employed on 8.B.V. now in France and appeared satisfactory until a few days ago when groans and judders were reported. In view of this report, we made tests by pouring water over a servo on which the outside edge was sealed and found it very easy to thoroughly wet the lining and cause judders and groans. The water entering by the holes designed to drain away any leakage past the oil seals on the shaft. These holes incidentally are spaced all round the distance piece which is not located radially and the spring plate acts as a diaphragm pump. To overcome this trouble we fitted a U section ring of Neoprene between the spring plate and the box and allowed a drain for oil by half cutting away the rubber ring at the bottom. With this arrangement it was possible to pour a gallon of water over the servo at the same time pumping the brake pedal without water getting in. Owing to the lack of maintained elasticity in Neoprene, we suggest that the Bakelite ring is modified as in the lower half of the attached sketch and the drain for the oil seal made by milling a slot in the bottom of the face on the box. This arrangement will do away with the machined piece now carrying the Bakelite ring and if fears are entertained that the bakelite will wear the aluminium face on the gearbox the ring could be prevented from turning by locating it in the drain slot. This arrangement should give us the same results as the Neoprene ring but would diminish the number of parts | ||