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).
Steering tendency of cars to 'tuck under' when braking, analysing weight distribution and moment of inertia.
| Identifier | ExFiles\Box 154\3\ scan0006 | |
| Date | 8th December 1926 | |
| Oy5-E-12826 X36882 December 8, 1926. To: Mr. Hulley cc Mr. Nadin Mr. Burton Mr. Hives ✓ Mr. Haldenby From: Mr. Olley Re Steering Attached is report from Hives of November 23rd on steering dealing with the tendency of the cars to "tuck under" when brakes are applied violently when turning a corner. Accentuated -he says- by the weaker springs they have fitted in the side steering tube, and by 6-3/4" tires. He quotes the heavier cars as being worst. Their limousine with 5 passengers and 100 lb. luggage has 43% of weight on front tires and 57% on rear. MX{John H Maddocks - Chief Proving Officer}-2 the other day with 5 up and 200 lb. baggage had 40% on front and 60% on rear, a considerably worse condition. Their braking is approximately 40% front, 60% rear. Ours is 38% front, 62% rear, but our total braking for a given effort on the pedal is only 80% of theirs. So that for a given effort on the pedal we get 76% of their front braking and 83% of their rear braking. The similarity of conditions makes me think that their "tucking-under" and our swerving to the left, are related, although we and Hives are talking of totally different effects. Moment of Inertia of heavy cars. It is worth while noting that as the moment of inertia of car about a vertical axis through the C.G. increases, we know that it tends to become uncertain in its steering and tends to swerve badly on small provocation. As weight is added to the rear of any of our cars we get this effect which apparently is due to increased angular momentum when turned out of a straight line. A thing like the Dodge truck with the load at the rear becomes particularly bad. This will probably explain some of the trouble on MX{John H Maddocks - Chief Proving Officer}-2. | ||