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).
Comparison of cellulose lacquered cambric covered maconite H.T. cables for car and 'R' engines.
| Identifier | ExFiles\Box 58\1\ Scan206 | |
| Date | 18th March 1930 | |
| X 6009. Cellulose lacquered cambric covered maconite H.T. Cable. (For Car and "R" engines). The following should be noted:- (1) The cable covering only cracks when bent about at sharp angles and then it is only the lacquer that cracks not the cambric. On 14.G.IV. the cable shewed cracks before the car went away. This was largely due to the difficulty of getting this cable in the tube (diameter slightly above limit of 7 mm.), but also due partly to people testing the flexibility in position. (2) The cable inside the covering is standard maconite H.T. cable and therefore it can only be worse in appearance. (3) The "R" engine cable is a considerable improvement. The lacquer treatment is much better and permeates the outer cambric layer completely, which was not the case on the car cable. There is also provided an inner layer of cambric tape between the maconite and the outer lacquered layer. Also the diameter is larger, so that the flexure of the cambric is less. (4) The lacquered cambric covering of the maconite provides definite protection against oil and petrol and still does so to a great extent even if the covering is cracked; the inner spiral of cambric tape assists in this protection by taking up any oil or petrol which gets through the cracks. Tests have been made to prove this point. Bare maconite absorbs petrol or volatile oil, swells and becomes mechanically weak. This fault is common to all types of bare rubber covering. (5) The more finished appearance of black cellulose lacquered cambric covered H.T. cable is all in favour of this on the special "R" engines for which it is proposed. E.P.K. | ||