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).
Engine component testing, detailing modifications and test results for articulated rods and bearings.
| Identifier | ExFiles\Box 179b\3\ img267 | |
| Date | 17th February 1933 | |
| -2- Ha.7/WJ.17.2.33. Cont'd.{John DeLooze - Company Secretary} (2) A further modification is - bolt centres slightly altered. Owing to the failure of number (1) we do not think Number (2) will be a complete cure. (3) A curved base on the rod. Sets of these rods are now ready for test and will be run under the same conditions under which the others have failed. The other possible cure is of course articulated rods but we have no design of articulated rod to suit existing crankshaft. The articulated rod demands a wider big end bearing therefore we have got to carry on the tests with number (3). Apart from the lugs cracking we have had several cases on development engines and one case in service of the bearing block itself cracking. On the high powered test with the white metal bearings these cracked up after every two hours. After slight modifications to get rid of sharp corners, and with the manufacture of lead bronze bearings the bearings are quenched at high temperature, which we think improves the condition of the steel) the result is that we have been able to run eleven hours on lead bronze bearings at the high powers. A further improvement we expect in this direction is by the use of C.W.S. instead of mild steel blocks. On the general question of articulated rods versus plain and forked rods, on the tests we have run so far, the articulated rod has proved to be more reliable. On the articulated rod we have run 19 hours at approximately 900 HP. without any signs of failure. On the forked rods we have broken an ear after 11 hours of similar running. The articulated rod is heavier and is designed from the experienced of the "R" engine. We believe if the same weight was put into the forked rod and a considerable amount of development, it could be made to stand up as well, but as we cannot possibly afford to do everything we say that for all future engines we ought to concentrate on articulated rods. We have still got to look after the 1000 engines already made, and the others which are contemplated with the existing rod. If the articulated rod could be made to go on the existing crank this might prove to be the best way out we think it is too much to ask to scrap crankshafts, because these are giving no trouble whatever. The articulated rod at present is used in conjunction with the shorter stroke. The reason for the shorter stroke is that the rod fouls the bottom of the cylinder liner and if the standard liner is used it must be shortened by .250". This also means shortening the piston because we have not been able to get | ||