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).
Letter from Cadillac Motor Car Company discussing research into wheel fight, wobble, and shimmy.
| Identifier | ExFiles\Box 173\4\ img238 | |
| Date | 9th March 1936 | |
| COPY Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer} * N.S a F.J.H See me CADILLAC MOTOR CAR COMPANY. DETROIT, MICHIGAN. Rm{William Robotham - Chief Engineer} March 9th 1936. B.I.Day Esq., Rolls-Royce Limited., Derby, England. Dear Mr Day, Thanks for yours of February 26, 1936. At the moment I am chiefly concerned with your notes on Wheelfight in this and in your letter of January 14, 1936. Also will you refer to my note to Rm.{William Robotham - Chief Engineer} of February 26, 1936?. Based on recent investigations both on Bump Rig and road I have formed the following ideas, which are not to be regarded as "idees fixes", but represent our experience to date:- (1) When we put a car on the drums with four cams per drum (9" long 1" high) and stir up wheelfight we see on all cars of all types at least a vestige of two distinct types of wheel fight - The first at 400 a minute is a close relative of Low Speed Wabble. The second occurs worst at wheel hop frequency (550-600 a minute) and is related to shimmy. (2) Our experience to date is that a car is good for wheel fight on the road may show a lot of the first type (on cams) but will show only a vestige of the second. The first, low frequency type is easy to damp out on the road. The second is not so easy to damp out although it is certainly affected by:- Friction in kingpins and rod-joints. Front shock absorber setting. Frame stiffness. | ||