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).
Design of connecting rods for the Spectre engine, specifically addressing dismantling difficulties.
| Identifier | ExFiles\Box 93\1\ scan0108 | |
| Date | 23th March 1933 | |
| X469 314 To-R.{Sir Henry Royce} from E.{Mr Elliott - Chief Engineer} c. Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} Hs.{Lord Ernest Hives - Chair} By.{R.W. Bailey - Chief Engineer} E.4/HP.23.3.33. SpectreCodename for Phantom III Connecting Rods. ------------------------ Referring to the question of type of rod to be used on the SpectreCodename for Phantom III, it will be remembered that the design finally chosen was articulated. In going over this matter again we have come up against a difficulty in dismantling the piston of the master rod when removing the pistons and rods from an engine in position on the chassis without removing crankshaft. As originally arranged, after disconnecting the articulated rod by moving the pin endways, the master rod was to be pushed as far upwards as possible until the piston pin showed above the cylinder top to remove pin and piston. Unfortunately the pins are a shrink fit in the pistons, and our standard practice is to assemble by heating the latter in boiling water, when the pin will slip into place. Conversely when dismantling an engine the piston is plunged into boiling water for extracting the pin and separating the piston and rod. We have carefully confirmed that this practice is followed in all departments at the works and is necessary. It is not possible to drive out the piston pin without causing damage. This definitely favours side by side rods or fork and blade connecting rods. The latter scheme limits the diameter of the crankpin too much when the forked end is made to withdraw through the bore so we are left with the former. We should like to have your views on this point and in the meantime we are looking into the effect on the design of side by side rods. The majority of multi-cylinder "V" chassis engines employ side by side rods. Marmon and Voisin are forked. E.{Mr Elliott - Chief Engineer} | ||