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).
Instructions for testing and adjusting a contact breaker and distributor, detailing current, speed, and tension specifications.
| Identifier | ExFiles\Box 70\4\ scan0118 | |
| Date | 7th July 1927 guessed | |
| -2- Contd. (1) The contact breaker shall be connected up to an ammeter, a twelve volt battery, and a non-inductive resistance of zero temperature coefficient, all in series, the last named being of such a value as to permit the passage of exactly one ampere when the points are in contact. The distributor shall then be driven at a speed of about 700 r.p.m. The correct platinum point setting will then be such as to permit the passage of a current of .55 ampere during rotation. The resulting platinum gap should be noted for future reference and should lie between .017" and .021" but the adjustment should initially be carried out as above. (2) The distributor should now be speeded up to 1800 r.p.m. when the average current should not be less than .46 ampere. If it is, it is probable that the set of the contact breaker spring requires increasing. That screw of the two securing the contact spring clamp nearer to the contact points shall now be removed. Through the hole thus available, a wire, having a hook at each end is inserted and attached to the contact end of the rocker arm. A spring balance is now hooked on to the other end of the wire and the tension required just to break contact (and indicated by the ammeter in circuit) is noted, care being taken that the wire is clear of the side of the hole. This tension should lie between the limits .9 and 1.2 lbs. There should be no readable difference between Contd. | ||