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).
Production, inspection, adjustment, and testing procedure for a distributor and contact breaker.
| Identifier | ExFiles\Box 168\3\ img135 | |
| Date | 13th April 1939 | |
| Specification No. ELC.23/DR.426. DB.{Donald Bastow - Suspensions}2287. Production, Inspection, Adjustment and Test of R.R. distributor and contact breaker suitable for Wraith and Bentley V.{VIENNA} (1) Inspection should be made that the contact points are exactly opposite with the contact surfaces bedding centrally. This can be done accurately and should be done by running the distributor with a coil in circuit, in which case the surface of the points will be characteristically marked where electrical contact has occurred. The points should be adjusted until this mark becomes central on their surfaces. Ascertain that the contact spring is free from cracks, the contact lever complete with spring should be temporarily removed and the lever pushed back against the spring as far as possible without showing any signs of distress, also see that the cam is greased with mobile grease No.2 and the contact lever pivot lubricated with one drop of oil. (2) The contact points must break every 60° during rotation with a tolerance limit of plus or minus one degree, overall error not to exceed two degrees. These limits must be strictly adhered to. (3) By means of a spring balance suitably attached to the contact end of the rocker arm, the tension required to just break contact indicated by a lamp in the circuit, should lie within the limits of 17 - 18 ozs. This tension should not be less than 17 oz., or there will be a tendency for point bounce at the maximum speed. It is importance that there is no readable difference between just making and just breaking contact, this indicating absence of excessive friction at the pivot. (4) The contact breaker shall be connected in series with an ammeter, a 12 volt battery and a non-inductive resistance of zero temperature coefficient, the last named being of such a value as to permit the flow of exactly one ampere when the points are in contact. The distributor shall then be driven at a speed of 300 r.p.m. The correct contact point setting will then be such as to permit 0.55 amperes to flow during rotation. The resulting gap should be noted for future reference. | ||