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).
Secret memorandum detailing design changes to a fabric engine coupling.
| Identifier | ExFiles\Box 66\4\ scan0143 | |
| Date | 29th April 1925 | |
| +8305 TO BV. FROM AJS. SECRET. AJS1/M29.4.25. Copy to EH. HS. {Lord Ernest Hives - Chair} E. {Mr Elliott - Chief Engineer} A. {Mr Adams} C. FABRIC ENGINE COUPLING. +8305 We send herewith LeC. 2056. on which we shew a fabric engine coupling, the disc of which is .775 thick, the outside dia. remaining as before. The bolt and set screw centres are however slightly contracted in radius. With the scheme shewn on this drawing we have substituted set screws and a conical nut for the conical headed bolts used previously, thereby eliminating the machined out clearance feature on the front of gearbox ball bearing housing and cover. The facing it should be noted, carrying the front ball bearing cover has been set back relative to the layshaft similar facing in order to give extra clearance, and lock nuts and plate washers are to be used in holding the 1st. motion shaft ball bearing cover in position, also to gain space. We believe you will find that the cover itself on the 1st. motion shaft has been slightly decreased in depth but we believe there is ample room for the core of the oil drain pocket. We have shewn the 2 Woodruff keys as originally specified for holding on the rear spider, but if the 4 smaller ones are satisfactory we are quite in agreement with these. The method of locking the nut holding on the rear spider has been altered. The nut is now a hex; one and over it fits a pressed steel cap having tabs turned down into holes in the spider, the number of holes combined with the hex: nut giving a differential locking scheme. It should be noted further that the oil retaining thread on the spider has been shewn shallow in distinction to the deep thread indicated on some of the Derby details. It is our impression here that this shallow thread should be equally as effective as the deep one, and we believe has been used on aero work quite successfully. If there is any reason for this not being the case we should be glad to know for future work. It is very difficult to be certain on a scheme of this sort that the parts will go together when we have such small clearances, but we believe that with the conical spigots and reinforcing plates registering in the rear spider, it will enable a little manouvreing in getting the disc into position. AJS. | ||