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).
Clutch balancing issues, including flywheel hole tolerances and cover pressing distortion.
| Identifier | ExFiles\Box 130\3\ scan0110 | |
| Date | 17th August 1939 | |
| -2- Rm{William Robotham - Chief Engineer}/NRS.1/JH.17.8.39. Balancing. Some difficulty has been experienced by B. & B. in checking the balance of some of the clutches we have returned owing to the fact that we have reamed out the holes which locate the clutch, presumably to suit some of the earlier flywheels which were not jig drilled, the holes in the cover pressing are drilled in America and B. & B. pass them with a plug gauge of .313 GO and .3145 NOT GO, and a number of new ones I tried were within these limits, although in some holes the NOT GO gauge had perhaps .001 clearance, but some of the holes we have reamed had fully .005 clearance above the .3145 gauge, so for the present we will certainly have to check and correct the balance. Now that the flywheels are jig drilled, we anticipate much less trouble in this respect, and if we can ultimately cut out the reaming, or not ream more than say .001, we may hope to ultimately cut out re-balancing and this point is certainly worth watching carefully with a view to effecting economies and improvements as we gain experience. There is also the question of distortion of the cover pressing as a result of damage in transit or rough handling to consider, it being borne in mind that the triangular pressing of the long type is not so rigid as the circular flange of the B. & B. type, and if the holes do not register, it might be found better to spring the cover over the bolts rather than to enlarge the holes by reaming. A distorted cover pressing is also likely to upset the accuracy of the release lever setting which is another reason for our carrying out this final adjustment, and it is important that the studs on the setting plate agree accurately with the bolts of the flywheel. There is no doubt that a general all round improvement can be anticipated as B. & B. get down to production, and it will be realized that the first batch of clutches were made largely from parts ordered by cable from America, and ultimately more parts will be made in England. Rm{William Robotham - Chief Engineer}/NRS. | ||