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).
Letter from EKCO regarding body wiring and shielding principles on a Park Ward 40/50 HP chassis.
| Identifier | ExFiles\Box 63\2\ scan0012 | |
| Date | 11th May 1935 | |
| /6153. W. S. VERRELLS Chairman & Managing Director E.{Mr Elliott - Chief Engineer} K.{Mr Kilner} COLE Sub-Managing Director E.{Mr Elliott - Chief Engineer} R.{Sir Henry Royce} PRING R.{Sir Henry Royce} E.{Mr Elliott - Chief Engineer} CORNWALL Directors EKCO ALL-ELECTRIC and BATTERY RADIO TELEGRAMS EKCO SOUTHEND-ON-SEA TELEPHONE SOUTHEND 49491 8 Lines RIC/JP E.{Mr Elliott - Chief Engineer} K.{Mr Kilner} COLE LTD EKCO WORKS SOUTHEND-ON-SEA 11th May 1935. Rolls Royce Ltd., DERBY. For the attention of Mr. West. Your Ref: Hs{Lord Ernest Hives - Chair}/Wst.8/MA. Dear Sirs, Thank you for your letter of the 9th inst., with regard to the body wiring on the Park Ward 40/50 h.p. chassis. We have noted your remarks regarding the insulation of the shielding, but would state that it is not intended that the shielding should ever be connected, except to negative earth returns. In fact, the essence of the shielding principle requires that both ends of the braiding be at ground potential. In these circumstances you will agree that insulation on the outside of the shielding is not so important. Where it is not desired to earth either side of the battery, or where twin wiring is required for any other reason, we supply a cable suitable for this, a sample of which is enclosed (part No.A4869). Actually, however, we have never found it necessary to use this, except on motor-coaches. We are, of course, quite prepared to use twin shielded wiring should you still require it, but it would mean that with the shielding grounded one of the internal conductors would be in parallel with it. It is evident that Park Ward's electrician made a mistake in this instance, and we attach a sketch showing the arrangement normally employed, which contd................ IMPORTANT NOTICE. "LIMITED LICENCE" "Ekco products are patented and are supplied upon condition that the recipient accepts a licence under the patents and agrees to sell only at the prices fixed by the Makers. Violation of this by anyone renders him liable for damages." | ||