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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 notes and formulas for calculating vehicle roll rate, anti-roll bar effects, and rolling weight.

Identifier  ExFiles\Box 127\4\  scan0222
Date  2nd July 1940
  
-3-

Section III.
The roll rate is obtained by drawing tangents to a graph in which roll couple in lb.ft. is plotted against roll angle in degrees.

The couple = (weight difference x track) / 2

The angle = (diff. in ht. between wing stickers x 57.3°) / (distance between wing stickers)

Tyre roll rate= (tyre rate x (Track in inches)^2) / 1375

The anti roll bar effect is obtained by subtracting the roll rate of the front suspension less anti roll bar from the roll rate of the front suspension with anti-roll bar.

On development work, after tests have been done with two or three anti-roll bars, a graph can be plotted of anti-roll bar dia. versus anti-roll bar effect.

The value of (measured roll rate less anti-roll bar) / (calculated ditto ditto) should be between .95 and 1.05.

Section V.{VIENNA}
Obviously the spring track should be used when calculating the suspension roll rate.

Section VI.
The rolling weight on our selected car is Kerb weight plus 600 lb. - rear unsprung.

The latter is the only part which does not roll.

340 lb.ft/deg. is considered to be a good value for roll rate/2,000 lb. of rolling weight. If the centre of gravity is lower than normal (about 25" from the ground) a lower figure would be desirable.

2,000 lb. is taken as a unit of rolling weight in order to fall into line with American practice.

Test headings etc. can be modified to suit departures in suspension details from those on the selected car.

Rm{William Robotham - Chief Engineer}/GB.
  
  


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