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).
The effect of pull-off spring strength on thumping in the New Phantom's 4-wheel brakes.
| Identifier | WestWitteringFiles\N\2October1925-December1925\ Scan122 | |
| Date | 4th November 1925 | |
| R.R. 493A (50 H) (D.D. 31, 12-6-25) J.H.D. EXPERIMENTAL REPORT. ORIGINAL Expl. No. REF: Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}2/LG4.11.25. To DA.{Bernard Day - Chassis Design} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} NEW PHANTOMCodename for PHANTOM I - 4-WHEEL BRAKES. +S420 With reference to DA{Bernard Day - Chassis Design}3/M22.10.25. We find that increasing the strength of the pull off springs on the Phantom beyond the present standard does not have a beneficial effect on thumping. With no friction on the swinging arm, increasing the strength of the pull off springs does not increase the intensity of the thump but extends the road speed period at which it occurs. More friction, if anything, is required to eliminate thumps under these circumstances than when the car is in standard condition. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||