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).
Specification sheet for springs with a 10-inch static deflection for the Phantom III with Wraith wheel movements.
| Identifier | ExFiles\Box 95\2\ scan0238 | |
| Date | 27th October 1937 | |
| 27.10.37. SPRINGS OF 10" STATIC DEFLECTION 1200 LBS. NORMAL LOAD, FOR PHANTOM III WITH WRAITH WHEEL MOVEMENTS. ROOM ALLOWED FOR PACKING. Requested by Rm{William Robotham - Chief Engineer}/Les.{Ivan A. Leslie} Inner Spring. Outer Spring. Wire diameter 0.465" 0.650" Mean diameter of coils. 2.810" 4.125" No. of effective coils. 8 1/4 6 1/4 Normal load. 1147 lbs. 2215 lbs. Normal deflection. 3.210 3.80" Free length. 9.285" 10.250" Maximum load. 1517 lbs. 2820 lbs. Maximum stress - uncorrected. 107,800 lbs.sq. in. 107,800 lbs.sq. in. Maximum stress - corrected. 134,000 lbs. 132,800 lbs.sq. in. Maximum deflection. 4.250" 4.84" Rate per inch. 357 lbs. 584 lbs. Rate per inch of combination. 941 lbs. Rate per inch at wheel. 120 lbs. Solid length of inner = 4.725" Room for packing 0.310" Solid length of outer = 5.150" Room for packing 0.260" Maximum packing corresponds to a load increase at the wheel of 93.5 lbs, and for increases more than this two springs of increased free length should be used as on the present Phantom III, other particulars being as above. The new free lengths would be : Inner 9.565", Outer 10.56", for normal load of 1300 lbs. | ||