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).
Rattle issue with the Phantom II Synchro Mesh Gear Box due to excessive clearance.
| Identifier | ExFiles\Box 15\5\ Scan344 | |
| Date | 21th October 1932 | |
| GRY{Shadwell Grylls} See me x7310. BY Hs{Lord Ernest Hives - Chair} c. By/PWD c. Brt c. Spt/Mr Norman from Mx.{John H Maddocks - Chief Proving Officer} MS/T21.10.32. HS{Lord Ernest Hives - Chair} PHANTOM II SYNCHRO MESH GEAR BOX. We have come up against a trouble on a number of Phantom II Gear Boxes of a rattle when picking up on top gear from low speeds up to about 30 miles per hour. It is something similar to the "bubble" that we used to have from the continuous gears on the Silver Ghost Gearboxes. Some chassis are entirely free from it and on others it is very pronounced. Some few days ago I demonstrated a case to Rm.{William Robotham - Chief Engineer} and in the meantime we have been carrying out some investigations of a bad case to find out what actually caused the trouble. We feel we have now definitely located it as being due to the varying amount of clearance between the cam and its slot on the Synchro-mesh mechanism. This allows the mass of the Synchro-mesh mechanism to oscillate. On a particularly bad instance of this trouble we have temporarily increased the size of the two cams by nickel depositing - this has entirely cured the rattle. We find that there is quite a big limit allowed on the parts in question, the clearance can vary from .005" to .012". We consider that the clearance should not exceed .005". At the present moment we have four gear boxes which are not passable for rattle. Will BX please consider the advisability of immediately instructing some cams to be produced sufficiently oversize to suit the gear boxes in question. We do not think that this will present any difficulties as we understand that there is plenty of material on cams as produced before grinding. contd- | ||