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Analysis of transverse axis net couple and frame twist, including calculations and a diagram of a rear suspension layout.


Identifier  ExFiles\Box 26\1\  Scan041
Date  19th March 1965
  
- 4 - Tln/CJC. 3.FL. 19.3.65

About transverse axis, net couple

= We₂ - We₁ ~ twisting frame in opposite direction to longitudinal axis couple.

If a = b, the twist of the frame will be zero when

(e₂ - e₁) = b.

Putting figures to this, if we assume that b = centroidal distance between sills = 60", the crossmembers would be conveniently situated at the dash and rear seat heelboard. The minimum value of e₁ possible = 15" so for zero twist e₂ = 75". This results in a wheelbase of 150" which is rather long. Any departure from the above figures will result in some twist but much less than with a conventional arrangement.

The ideal set-up is a front engine front wheel drive car, the load crossing obviously taking place at the rear end. One possible suspension layout which achieves the desired frame loading is shown below:-

FIGURE 5

STABILISING RODS.
REAR WHEELARCH
DAMPER
FRAME
FORWARD
LONGITUDINAL TORSION BAR
BEARING TO REDUCE BM ON TORSION BAR DUE TO CORNERING FORCE.
FORGED H.T.S. LEVERS. -NATURAL FREQUENCY OF UNDAMPED LENGTH >1,000 C.P.M.

Continued.........
  
  
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).


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