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).
Modifications and trial experiments for EAC & Goshawk connecting rods.
| Identifier | Morton\M3.5\ img051 | |
| Date | 12th June 1925 | |
| TO HS.{Lord Ernest Hives - Chair} FROM R.{Sir Henry Royce} R1/M12.6.25. EAC.& GOSHAWK CONNECTING RODS. [Handwritten: X 5030] Referring back to the old 40/50 rods, the only great change we can find is in not fitting bushes to the big ends. I therefore think we should try some bushes both in bronze and mild steel, as shewn on Lec. 2081. [Handwritten: + soldered] My impression from an examination of the tested rods is that the whitemetal is insufficiently keyed to the steel, and I have suggested some axial grooves in the big end in combination with the circular grooving. This is also shewn on drawing Lec. 2081. which has been sent to Derby. The whitemetal might be made to adhere more firmly by first plating the big end with copper, but the difficulty may be that the copper will not firmly attach itself to the alloy steel; nevertheless a trial could be made unless we already have some experience with this idea. As regards the lubrication of the big end we do not usually like oil grooves because they allow the oil to squeeze out under load, but it may be necessary to use them to replace the oil more quickly. Try therefore some grooves extending 120º top and bottom, such as we found necessary on the Eagle. Try also independently a flat on the crankpin about 1.2" long. Summarising the modifications suggested for trial, experiments should be made as follows:- (1) Axial grooves in combination circumferential grooves - chequered grooving Lec. 2081. Try on (a) Mild steel rod. (b) Alloy steel rod. (2) Rod with big end bushes - Lec. 2081. This rod has been designed with a somewhat stiffer cap. (a) Bronze bushes whitemetalled. (b) Mild steel bushes with chequered grooving for whitemetal. (3) Copper plating before whitemetalling. (4) Increase supply of oil to big end. (a) Grooves top and bottom. (b) Flat on crankpin. (5) Test at still higher speeds by using double valve springs in place of the valve stem glands. R.{Sir Henry Royce} | ||