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).
Comparative analysis of suspension spring characteristics between the New Phantom, 20 HP, and Lanchester models.
| Identifier | ExFiles\Box 4\7\ 07-page38 | |
| Date | 27th January 1926 | |
| To C.J. from D.A. X441 DA{Bernard Day - Chassis Design}1/M27.1.26. GEOFFREY SUMMERS - 117-MC. X.4117 X.441 X.8410 X.8410 Replying to CJ2/D25.1.26, all the illustrations and drawings we have here show the springs on the 20 HP. Lanchester arranged in the opposite way to that described by PN.{Mr Northey} viz: with the rear end shorter than the front end. The design may have been changed recently, but we think it more likely there is a clerical error in PN{Mr Northey}'s note. Assuming our illustrations are correct comparing the 20 HP. Lanchester with cantilever rear springs, underslung and eccentrically loaded, without shock dampers, with first the New PhantomCodename for PHANTOM I with cantilever rear springs overslung, and centrally loaded, and friction shock dampers, and secondly with the 20 HP. RR. with semi elliptic rear springs, underslung, and centrally loaded, and with friction dampers, the following applies. As compared with the 20 HP. Lanchester :- NEW PHANTOMCodename for PHANTOM I. (1) Is less liable to roll due to overslung springs. (The underslung spring has been several times tried on RR. cars, each time being condemned on account of rolling. This probably explains why the Lanchester people find it necessary to fit an anti-rolling device). (2) Equally flexible in vertical suspension, the eccentric loading of the spring on the Lanchester making no difference to this. (3) Is less rigidly held laterally, the shorter rear end of the eccentric Lanchester springs being stiffer for an equal total length of spring. But in this connection it may be pointed out that when one wheel lifts the tendency to side shock is reduced in the Lanchester by the springs being nearer the ground,(the ideal position for these being of course level with the ground. 20 HP. R-R.{Sir Henry Royce} Has a nearly equal tendency to roll, but the slightly higher springs and superior lateral stiffness probably makes just sufficient difference. Equally flexible in vertical suspension. Is much more rigidly held laterally, the position of the springs with reference to the ground being about the same, but being more rigid than the cantilevers. In spite of the stiffness however, it is probable that side shocks are no more noticeable than on the Lanchester, and for the same reason - viz: the lower position of the springs makes the side motion small. contd :- | ||