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).
Specification for H.T. ignition cables for Spectre and Bentley chassis.
| Identifier | ExFiles\Box 168\1\ img215 | |
| Date | 4th October 1935 | |
| Y617. By.{R.W. Bailey - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Wst. c. to Roy.{Sir Henry Royce} c. to Sft.{Mr Swift} Hs{Lord Ernest Hives - Chair}/Wst.17/MA.4.10.35. H.T. IGNITION CABLES FOR SPECTRECodename for Phantom III AND BENTLEY CHASSIS. The correct specification for the cable to be used on these chassis is as follows :- (1) Conductor. Stranded tinned annealed copper wires. Number of wires 19. Diameter of wires .012". (2) Dielectric. This shall consist of compound vulcanising rubber applied in not less than two layers and shall contain not less than 40% by weight of rubber of a quality not inferior to first grade British Plantation rubber. The conductor should be evenly centred in the dielectric. The rubber dielectric should be braided with strong cotton yarn and cellulose varnished with a sufficient number of coats so that the surface is smooth, glazed and free from pinholes. (3) Diameter. The overall diameter of the completed cable should lie between the limits .266" and .276". (4) Electrical tests. The completed cable must be capable of withstanding for at least 15 minites 15,000 volts (R.M.S.) applied between the conductor and the water after the cable has been immersed in water at normal atmospheric temperature for 24 hours. The cable we have tested complying with this specification, was obtained from the British Insulated and Helsby Cables Ltd., and H.T. ignition cable for SpectreCodename for Phantom III & Bentley should be exclusively obtained from this firm until we have suitably approved similar cable from Messrs. Macintosh Ltd. Hs{Lord Ernest Hives - Chair}/Wst. | ||