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).
Potential causes for seized main bearings, focusing on crank ovality and material analysis.
| Identifier | ExFiles\Box 146\1\ scan0270 | |
| Date | 3rd June 1938 | |
| 1245 W/P. from Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} Sr. Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}2/R.3.6.38. B.125.GP. Assuming that all precautions were taken and the main bearings were given the correct nip and clearance, it is difficult to conceive why Nos. 2, 3 and 4 should have seized as stated in your memo Sr/Wall/ET.30.5.38. In reply to your query we do not consider from our experience that the crankshaft bow is the trouble, as in the majority of cases when a unit is assembled with a bowed crank, the latter is perfectly free, such that what-ever load the bearings are subjected to by the bow will be negligible in comparison with the running loads. The ovality of the crank, if the same as you now state, i.e., .003 on No.4 when the bearings were first fitted may be responsible, dependent upon whether you gave your bearing the requisite clearance from the minimum diameter of the journal, or the maximum. Cranks with this amount of ovality should be corrected before new bearings are fitted. We should like to see the bearings in question as it is so much like the trouble we ran into with A.C.2 material that we should like to confirm they are the correct material, namely A.C.7., by analysis. Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} | ||