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 R.R. and Bentley chassis engines.
| Identifier | ExFiles\Box 163\7\ img322 | |
| Date | 20th June 1938 guessed | |
| b 013 SPECIFICATION No.E.L.9/1. H.T. IGNITION CABLES FOR R.R. AND BENTLEY CHASSIS ENGINES. (1) Conductor. The conductor shall consist of 40 strands of tinned annealed copper wire, each of .010" diameter. (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 to be evenly centred in the dielectric. A layer of ozone and oil proof compound is permissible on the outside if such compound is non corrosive at high temperatures and is reasonably odourless. (3) Dimensions. The overall diameter of the completed cable shall lie between the limits .266 and .276. (4) Electrical tests. The cable shall be capable of withstanding for 15 minutes 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 hrs. (5) A further sample shall be bent into a loop five times the cable diameter, and baked at 150°C for 5 hrs. After allowing to cool for 3 hrs. the sample still bent in the loop, shall be immersed in water and be capable of withstanding for 5 mins a voltage of 15,000 (R.M.S) (6) A sample shall be subjected to an ionization test. This shall consist of winding three turns of cable tight on to a metal cylinder 3" dia., the cylinder to be maintained at a temperature of 80°C. and the cable conductors connected to a suitable ignition coil, delivering 12,000 sparks per min. at 10,000 volts, the cylinder being connected to battery negative. The cable should be capable of withstanding this test for at least 250 hrs. without failure. | ||