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).
Report comparing design aspects of distributor mechanisms, including drive, bearings, and ventilation.
| Identifier | ExFiles\Box 37\1\ scan 108 | |
| Date | 25th May 1921 guessed | |
| Oy2 - G 25521 Sheet #3. pins engaging with a slotted cross piece on the rotor spindle. The Delco advance might be worth inspection by Mr. Royce, as these people have most experience of any maker in this country. When the latter type of advance is used, the overall height of the mechanism is very small; for example, the dimensions on the Westinghouse ignition of the distributor head and the body containing contact breaker and advance mechanism are 3-3/8" dia, X 4-1/4" high overall. (6) DRIVE: Generally the body carries a "tail" similar to the American Bosch ignition brought over by Mr. Hives, and standardized by the S.A.E.. This is shown in the attached sheet from the S.A.E. handbook, as well as the standard screwdriver drive attachment, which is off-centred so that it can be engaged in only one position. The turned outside dia. of the tail permits the hand-advance to operate by twisting the whole head. The Delco Co., however, find that the earth connection through the tail is not good enough and therefore provide a slotted sector as shown in the enclosed sketch, which makes a firm contact through a spring bolt and also limits the travel of the hand-advance. (7) BEARINGS: The average maker depends on the single plain bearing below the automatic advance to do everything. Delco and Bijur, however, do better than this in providing quite a substantial ball bearing above the automatic advance and just below the cam, as shown in the sketch. (8) VENTILATION: The ball bearing will corrode, however, if the contact breaker case is not sealed fairly well at the bottom and thoroughly ventilated. The seal is generally a felt ring, and the ventilation two holes in the contact breaker case which are screened from direct dirt by the clips holding the distributor head (as on the American Bosch ignition). | ||