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).
Procedures for servicing Bentley main bearings.
| Identifier | ExFiles\Box 146\1\ scan0155 | |
| Date | 31th December 1937 | |
| Rm{William Robotham - Chief Engineer}/Swd1.7/JH.31.12.37. BENTLEY BEARINGS. In reply to your memo. Sr.10/CPN.24.12.37. we consider that your suggestion of attending to the main bearings as a routine job when 4¼ litre cars come in for their first decarb. is rather an expensive precaution. Rm{William Robotham - Chief Engineer}/GWH.{George W. Hancock - Head Chateauroux} has evolved an apparatus whereby the oil flow through the bearings can be registered to assess whether the bearings are slack, in which case they need attention or are a good job, in which case the expense of actually dismantling and removing the bearings to inspect is saved. A drawing of this test rig is being made and will be sent to you. We understand that Rm{William Robotham - Chief Engineer}/GWH.{George W. Hancock - Head Chateauroux} will shortly be coming to see you and will be able to give you full details of this test rig and discuss bearings and their treatment. In the meantime we suggest that when a car comes in for its first decarb. after 10,000 miles, unless there are signs of bearing trouble by roughness, thumping, or oil pressure lower than usual there should be no inspection of bearings. Regarding the drilling of the extra oil holes in the crank, up to date grooving of the inter-mains and the take up of the main bearings when the car comes in for its bottom decarb. as you say between 18,650 and 21,750 miles, this we consider is the correct procedure. In the experience of Rm{William Robotham - Chief Engineer}/GWH.{George W. Hancock - Head Chateauroux} on the numbers of cars dealt with at Kingsbury in regard to bearings, he considers that the method of stepping liners to take up bearings can only be carried out really satisfactory by taking the engine out of the frame to do the job and to which we agree. It should be arranged that the stepping gives a .002 nip at each side of bearing and on both halves, after which the bore of the bearing should be checked for clearance on the crank journals. | ||