Four graphs showing J.III Rear low-pressure valve spring performance at varying RPMs.
| Identifier | ExFiles\Box 56\1\ Scan258 | |
| Date | 29th December 1932 guessed | |
| Top-Left Graph: J.III REAR. 40/40 LB. LOW PRESSURE. R.R.S.269. VALVE SPRING RATING 80 LB/IN. APPROX. 1" STROKE 90 R.P.M. DOUBLE DIAPHRAGM - A.C. & P.B. CONTROL LOAD MAX. 80 75% 53 50% 29 25% 12 ZERO 5 AXES LABELS: 308 LB/D" = 133 LB. , 120" I.S. Top-Right Graph: J.III REAR. 40/40 LB. LOW PRESSURE. R.R.S.269. VALVE SPRING RATING 80 LB/IN. APPROX. 1" STROKE 180 R.P.M. DOUBLE DIAPHRAGM A.C. & P.B. CONTROL LOAD MAX. 93 75% 66.5 50% 42.5 25% 27 ZERO 18.5 AXES LABELS: 308 LB/D" = 133 LB. , 120" I.S. Bottom-Left Graph: J.III REAR. 40/40 LB. LOW PRESSURE. R.R.S.269. VALVE SPRING RATING 80 LB/IN. APPROX. 1" STROKE 360 R.P.M. DOUBLE DIAPHRAGM A.C. & P.B. CONTROL LOAD MAX. 120 75% 82.5 50% 53 25% 36 ZERO 22.5 AXES LABELS: 308 LB/D" = 133 LB. , 120" I.S. Bottom-Right Graph: J.III REAR. 40/40 LB. LOW PRESSURE. R.R.S.269. VALVE SPRING RATING 80 LB/IN. APPROX. 1" STROKE 540 R.P.M. DOUBLE DIAPHRAGM A.C. & P.B. CONTROL LOAD MAX. 166 75% 122 50% 89 25% 66.5 ZERO 50.5 AXES LABELS: 308 LB/D" = 133 LB. , 120" I.S. | ||
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).