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).
Clarifying the effect of different tyre and rim sizes on the turning circle and out-of-centre point for B.111 and B.50 cars.
| Identifier | ExFiles\Box 158\1\ scan0182 | |
| Date | 4th May 1938 | |
| 1339 Da.{Bernard Day - Chassis Design} from Da{Bernard Day - Chassis Design}/DB.{Donald Bastow - Suspensions} c. By.{R.W. Bailey - Chief Engineer} c. Bm. c. Rm{William Robotham - Chief Engineer}/ARM c. Rm{William Robotham - Chief Engineer}/FJH.{Fred J. Hardy - Chief Dev. Engineer} c. De/Ev.{Ivan Evernden - coachwork} Da{Bernard Day - Chassis Design}/DB.{Donald Bastow - Suspensions}11/G.4.5.38. FJH{Fred J. Hardy - Chief Dev. Engineer} TURNING CIRCLE, OUT-OF-CENTRE POINT AT ROAD, AND TYRE SIZE. B.111 and B.50. The accompanying table is intended to clarify the position with regard to the effect of different sizes of tyres and rims on the turning circle or out-of-centre point, or both, for B.111 and B.50 cars. Against a number of tyre sizes are listed, first, the lock angle of the outside wheel for a lock angle of inside wheel of 41°, and the corresponding turning circle, for the present out-of-centre of 2.17", after adequate clearance has been left between tyre and cross steering ball joint (the clearance allowed is 0.375" approx. in the worst lock and bump conditions). Subsequently the out-of-centre point dimensions required to obtain given turning circle diameters for the different tyre sizes are given. Turning circle diameters for both B.50 and B.111 are given. It should be remembered that if the same cross steering lever is used for both cars, they will have corresponding turning circles if the out of centre is also the same, but since the wheels for B.111 and B.50 will probably be different in any case, there seems no reason why the extra tyre size should not be accommodated on B.50 by increase of out-of-centre point. B.111 is the car on which the good turning circle is desirable, in view of the likelihood of comparison with B.11, and B.111 is also the car on which harder braking is probable and on which the smaller out-of-centre point is therefore desirable. Such a change in out-of-centre point for B.50 could be accommodated in the wheels, and would, of course, then alter front and rear tracks by a small amount. Da{Bernard Day - Chassis Design}/DB.{Donald Bastow - Suspensions} | ||