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).
Vehicle suspension, ride quality, testing instruments, and the impact of balloon tires.
| Identifier | ExFiles\Box 43\2\ Scan102 | |
| Date | 10th March 1926 | |
| Oy3-E-31026 -2- March 10, 1926 Am inclined to think from recent experiences that a Packard, for instance, rides better with Watson Stabilators, Gabriel Snubbers or some other rather "rough" device than with Lovejoys. To get the full benefit out of Lovejoys it is necessary to fit the Packard first with softer springs front and rear. But the result in quality of riding (rather than mere safety on rough roads) is well worth the change. Newton and Norton instruments. Am getting particulars of these for you. The Norton machine draws a picture such as I sent you, with a spot of light on a continuous film. It is therefore an inspection rather than a measuring device. The Newton machine counts the aggregate changes in acceleration per mile, in units of 2 g.{Mr Griffiths - Chief Accountant / Mr Gnapp} and is therefore useful for production testing. We shall shortly be testing one of these. Both measure acceleration and not displacement. This is done by arranging in each case that the natural vibration frequency of the deflecting arm is considerably higher than any frequency liable to be met with in use. In the Norton machine the frequency is several thousand per second I believe. In the Newton about 700 per second, so that nothing but perhaps high speed with hard tires on cobbles could get within range of its frequency. You refer to the cushion riding worse than the floor on the Norton graph. This was actually the case in the car in question, and we find it to be often the case. For several years we have noticed that when cushions are badly made one often gets better riding by removing them and sitting on a rolled up coat or rug. I suggest that perhaps we are at cross purposes in this. You may be judging riding qualities by driving fast over rough roads. We feel that to prevent damage to passengers on rough roads is the easiest part of the job, but the difficulty is to make a car which will be really comfortable throughout the range from 20 to 45 m.p.h. on a good road with a slight wave in it. Balloon tires. Mr. Burford made a suggestion which reflected a different idea of riding qualities than the one we have over here. He said that possibly with the wider adoption of balloon tires road springs could be stiffened or finally eliminated. | ||