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).
Method for fitting and testing bearing liners of varying thicknesses.
| Identifier | ExFiles\Box 146\3\ scan0275 | |
| Date | 24th December 1936 | |
| -2- Derby ........Rm.{William Robotham - Chief Engineer} C; to ........Hd.{Mr Hayward/Mr Huddy} Sr/VAS/GM.24.12.36 We are now preparing several sets of test liners, each set will vary in thickness by .001", each set will comprise two liners of the following thickness : .095" - .096" - .097" - and .098". We propose to adopt the following method. After the amount of sinkage of the upper bearing into the crankcase has been determined and the joint faces of the cap reduced to the level of the joint faces of the lower bearing, we shall try various sets of the above liners to the bearing having treatment until one is found which will just allow the crankshaft to be turned. (turning the flywheel by hand). On the original liners of the bearing under treatment or if new RR.56 liners are fitted, the upper faces will be stepped as per Rm.{William Robotham - Chief Engineer} 271., corresponding to the amount of sinkage and if necessary that part of the liner which actually faces on the bearing section, will be reduced so as to leave as near as possible .003" clearance. EXAMPLE:- If the sinkage of the upper bearing is found to be .003" and the lower one .002", the faces of the cap will be reduced by .002", test liners will be chosen until the crankshaft can just be turned by hand. We shall then remove the test liners and supposing they have a thickness of .092" the final liners which we should fit to the bearing would have a .003" step in the upper face and that part of the liner which faces on the bearing section would have a thickness of .095", however, assuming that a car having attention has covered from 15.000 to 20.000 kilometers and taking the possibility of a certain amount of wear of the crankshaft journals, then in the above case we think that a liner having a thickness of .094" could be used without risk. We should however like to have your opinion. The following is the order in which we intend to attend to the bearings: 1. Rear bearing. 2. Front " 3. Centre " 4. Intermediate bearing. 5. Oil test. It will be obvious that when bearings have been attended to as above that we cannot definately state whether the working clearance are quite correct. We however, think that the method outlined will give a guarantee that the bearings will not be overtightened. Sr/VA | ||