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).
Review of a two-plate clutch for the Spectre model, comparing it to a single-plate clutch.
| Identifier | ExFiles\Box 93\3\ scan0001 | |
| Date | 17th February 1934 | |
| X644 3/2 To E.{Mr Elliott - Chief Engineer} from Da.{Bernard Day - Chassis Design} c. Wor.{Arthur Wormald - General Works Manager} Hs.{Lord Ernest Hives - Chair} By.{R.W. Bailey - Chief Engineer} Hsy. RHC.{R. H. Coverley - Production Engineer} SpectreCodename for Phantom III Clutch. In view of Rm{William Robotham - Chief Engineer}'s comments on the two plate clutch, we should like to review the case for using it on SpectreCodename for Phantom III. Compared with the single plate it has:- (a) Reduced pedal pressure. This comes about because the movement of the initial engagement plate is the same for two as for one plate, and the clearance movement for two need not be twice that of one. Further, as the loads on the levers and bearings are approximately half those of the single plate, the spring and friction in the operating gear can be reduced. (b) Reduced inertia. Because some of the gain from relative reduced movement can be used to reduce the diameter of the driven plate, which very quickly reduces its inertia. (c) Reduced pressure per square inch. Because the spring pressure is much less, and the plates not so much less. (d) The gain in ground clearance which might be expected is not in fact realised, as the controlling factor is the starter ring. Actually about .200 is gained instead of approximately 1.000 as one would expect. (e) Compared with the single plate the additional complication is very little. The difficulties in engagement experienced in America may be due to the system of riveting the two inner plates to a solid hub causing them to bend as wear proceeds. On N. Sch.3976/3977 (attached to By's copy) the following results have been arrived at - compared with Phantom - pedal pressure reduced from 40 to 35 lbs (not allowing for efficiency). Inertia reduced from 110 units to 71 units. Pressure per sq.inch. reduced from 32 to 27 lbs. | ||