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).
The development and testing of light alloy connecting rods for the 3 1/2 Litre Bentley.
| Identifier | ExFiles\Box 85\5\ scan0062 | |
| Date | 24th January 1934 | |
| 217 To E.{Mr Elliott - Chief Engineer} From Hs.{Lord Ernest Hives - Chair} c. to Sg.{Arthur F. Sidgreaves - MD} c. to Mor. c. to By.{R.W. Bailey - Chief Engineer} Hs.{Lord Ernest Hives - Chair}4/MJ.24.1.34. LIGHT ALLOY RODS. - 3 1/2 LITRE BENTLEY. It will be remembered that we started these rods going some time ago. The chief object of them is to put up the speed at which the crankshaft period will come on. Another advantage we expect to gain is improvement in big end bearing wear. We have now run four sets of these rods, two sets are running on the road, one of these are fitted to Ap's. car and another set to an experimental Bentley. We have done a considerable amount of endurance testing on the bed with them running at high speeds. On the beds we had one of the rods fail. There is a certain amount of doubt whether it was the rod which went first or the piston. Since that time, however, we have strengthened up the section which failed. All our experience so far on light alloy rods has been built up on those made by the Experimental Department. There is a new design LeC.3682 which we have just received the first sample forging. We do not expect these rods to function any differently to those we have been running but this scheme does involve a larger diameter gudgeon pin which will mean a new piston. At the time these rods were designed we were in trouble with pistons and it was thought that we may have to go to a larger diameter gudgeon pin, but as we have now got a satisfactory piston it is doubtful whether we should gain any advantage by the larger pin. We are running with the improved bolt as shown on LeC.3682. Hs.{Lord Ernest Hives - Chair} | ||