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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).
Technical discussion on the causes and gyroscopic effects of high-speed wheel wobble.

Identifier  ExFiles\Box 28\4\  Scan216
Date  30th December 1924
  
V457

EO.
c.Hs.{Lord Ernest Hives - Chair}
G.E.P.

HIGH SPEED WHEEL WOBBLE.
-------------------------

I have already seen Mr.Hale's article in the Journal of the S.A.E. Mr.Hale himself represents the tyre manufacturers, and is of course out to lift the burden of the trouble off the tyre makers.

It is quite well understood by ourselves, and moreso of course by R, that the wobbles themselves can be controlled by the introduction of dash pots and friction devices, but the addition of such parts would never be agreed to by R.{Sir Henry Royce} without some very material advantage to be gained in consequence.

Mr.Hales' demonstration that when blocks were put between the springs and the chassis, the wobble disappeared, proves nothing in regard to the origin of the wobble.

I do not think there is the slightest doubt but that the wobble itself is a re-acting gyroscopic effect set up in the first place by the amplitude of the tyre deflection, the absence of friction in the tyre wall, and the increase of mass on the arm of the front axle where front brakes are used.

The inter-action of these three factors sets up, under certain road conditions, a horizontal wobble, which in turn, by gyroscopic effects, produces a violent vertical bounce.

By introducing blocks between the springs and the frame, the mass of the axle is considerably increased, as the whole front of the car represents a part of the axle.

By doing this, the period of the wobble will of course be brought down to a very low speed, and at such low speed the energy is not sufficient to give gyroscopic re-actions of large enough effect to swing the whole mass so clamped together.

The experiments we are carrying out with 33 x 6.75" balloon tyres will give us some information in the near future.

Contd.
  
  


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