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).
Technical memo discussing the steering and suspension setup for a new lightened axle with balloon tyres.
| Identifier | ExFiles\Box 53\2\ Scan288 | |
| Date | 19th November 1926 | |
| To Hy.{Tom Haldenby - Plant Engineer} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to WOR.{Arthur Wormald - General Works Manager} 44565 Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}7/LG19.11.26. SPRINGFIELD. QUESTION 28. X4565 48430 With reference to Hy{Tom Haldenby - Plant Engineer}41/W16.11.26. The new type lightened axle has undoubtedly provided a steering that will cope with balloon tyres. However our tests have shewn that it does not pay to run balloon tyres at low pressures on the front of the 40/50 HP. car. We therefore recommend that the 6.75" tyres that we are at present fitting should be run at 40 lbs/sq.in. We think that under these conditions they give slightly better riding than the high pressure tyres on the front, and being able to run low pressure tyres at any required pressure on the rear very materially increases the comfort of the passengers. We know that in service the front tyre pressures will not be properly maintained, and have therefore carried out investigations to ensure that the steering shall be safe if these pressures fall as low as 30 lbs/sqin. The first essential is to have balanced wheels, the second to have efficient front shock dampers, preferably hydraulic. The third to have some frictional resistance in the steering gear. This is now possible owing to the new axle having made the steering so much lighter. We find that for Continental bad road conditions the friction required can be obtained by putting 1200 lbs. load on the balls of the spring loaded cross steering tube. Actually in order to promote wearing qualities it would be necessary to increase the size of the balls when the load could be reduced. However, R.{Sir Henry Royce} does not like spring loaded balls and has designed a hydraulic damper which functions between the cross steering tube and the axle. It will be several months before this is tested out; experiments with a R-R standard hydraulic damper in this position shew possibilities as long as no lost movement developes in the device. The load required is about 40 lbs. in the cross steering tube. The fourth essential is to have weak side steering tube springs. These minimise wobbles. The latest 40/50 HP. side steering tube has been designed with 1500 lbs. rating springs. The main point to be watched in connection with this tube is that the extra spring controlled travel of the balls does not promote 'taking charge' when the contd :- | ||