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).
Tests carried out to understand and reduce persistent steering joggling on Phantom II cars.
| Identifier | ExFiles\Box 182\M19\ img219 | |
| Date | 31th August 1931 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey} c. Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. E.{Mr Elliott - Chief Engineer} Da.{Bernard Day - Chassis Design} Hy.{Tom Haldenby - Plant Engineer} ORIGINAL x457 x9420 Hs{Lord Ernest Hives - Chair}/Lid{A. J. Lidsey}3/AD31.8.31. P.II. STEERING. We have lately carried out a number of tests to find out more about the conditions which are necessary to cause the persistent joggling which is prevalent in some degree on the majority of P.II. cars. The car used for the tests was 20-EX which is fitted with low rating springs front and rear and has damper loads to suit viz. Front 110/110 lbs. (.055" and .032" dia. leaks in H.P. valve) Rear 115/90 lbs. (one .055" dia. leak in H.P. valve). The engine mounting is the sandwich feet type; we would have preferred diamond mounting but there was no car available with this latest modification. 20-EX was mainly chosen because the steering was a very good example of bag joggling. Actually, the P.II steering is really very good for road shocks usually associated with running over very badly potholed roads; steering wheel movement from this cause is almost negligible. The objectionable feature is joggling which takes place on roads which can be described as normal main roads at speeds above 40 M.P.H. The joggling appears in some way associated with front end jellying - the same type of road produces it at the same speeds. Joggling, which in a new car is generally very slight, becomes worse as the car becomes older and more used, evidently due to wear in the various steering connections reducing the damping friction. In order to reduce the personal element from the comparative tests to be carried out, a device was made to measure the integrated steering wheel movement due to joggling and steering whilst the car was driven over the chosen test road. The device worked quite well and the results obtained from it agreed very well with personal opinions of comparative tests. | ||