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).
List of design changes for the 20/25HP Synchro-Mesh Gear Box on experimental chassis.
| Identifier | ExFiles\Box 104\4\ scan0092 | |
| Date | 20th January 1932 | |
| K5310. To [redacted], from RHC.{R. H. Coverley - Production Engineer} c. [redacted] Hs.{Lord Ernest Hives - Chair} RHC{R. H. Coverley - Production Engineer}5/EE20.1.32. Re: 20/25HP. 'Synchro-Mesh Gear Box The latest Gear Boxes fitted to Experimental Chassis, differ from the original design as follows:- (1) 10° cones EX.6686/7/8 instead of 6°. The latter were inclined to stick and were sluggish in action. (2) The shoe G.54747 for operating 3rd and top gear altered to Phosphor Bronze instead of C.H.N.S. owing to the latter material seizing. Whilst the/P/B. shoe has proved satisfactory, there is the risk of failure if casings were porous. In order to obviate this we suggest forged aluminium bronze shoes as an alternative. (3) The pegs EX.7419/20 for the synchro-mesh operating sleeve reduced to give a little more land for supporting the shoe. (4) The cones secured to the member by nuts and screws in place of rivets. (5) The tail bearing for the 3rd motion shaft altered to plain bush EX.7161 increased in length, instead of roller bearing. Lubrication is supplied by drilling through the root of the 1st motion shaft gear teeth. (6) The clearances for the synchro-mesh outer and inner sleeves have been increased to .007" to give ease in operation. (7) The clearance between the rear cover G.54918 and the coupling flange G.54919 which is an Acme thread for the oil retaining, has been increased from .005" to .010". -continued- | ||