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).
Diagram and procedure for testing servo efficiency using spring balances.
| Identifier | ExFiles\Box 178\1\ img098 | |
| Date | 13th July 1926 | |
| APPARATUS FOR TESTING SERVO EFFICIENCY. SPG. BAL. A SPG. BAL. B "STEP ASIDE" COUNTERSHAFT. TO FRONT THE ABOVE DIAGRAM SHOWS THE METHOD OF INSERTING THE MAXIMUM READING SPRING BALANCES IN THE LINKAGE WHEN ON THE CAR. THE RODS "CD" & "EF" SHOULD BE OF THE SAME LENGTH AS THE USUAL RODS EMPLOYED & IT IS ESSENTIAL THAT THE VARIOUS LEVERS ARE IN THEIR CORRECT ANGULAR POSITIONS THE UNDERSHIELD WILL HAVE TO BE REMOVED TO ACCOMODATE SPG. BAL "B". THE SAME ARRANGEMENT CAN BE USED ON THE GEAR BOX TEST RIG, BUT THE RODS F, G & H WILL HAVE TO BE FIXED TO SOMETHING. THE SAME ANGULAR POSITIONS MUST BE MAINTAINED AS WHEN ON THE CAR. WE TAKE THE VALUE B/A AS THE RATIO FOR COMPARING SERVOS. WHERE 'A' IS THE LOAD IN POUNDS RECORDED IN BAL. A.{Mr Adams} WHERE 'B' IS THE LOAD IN POUNDS RECORDED IN BAL. B. NOTE ON MAKING THE TEST:- IF TESTED ON THE CAR, THE BRAKING MUST NOT BE SUFFICIENT TO LOCK THE WHEELS & FOOT PEDAL SHOULD BE RELEASED BEFORE CAR STOPS. IF TESTED ON RIG, SERVO MUST NOT BE ALLOWED TO BECOME UNDULY HOT. AN AVERAGE SHOULD BE TAKEN OF ABOUT A DOZEN TESTS. AVERAGE RATIO B/A SHOULD BE WITHIN THESE LIMITS:- | RATIO B/A | MAX: VALUE | MIN: VALUE | |-----------|------------|------------| | | 2.5" | 1.5" | STAMPED TEXT: [ILLEGIBLE] 13 JUL 1926 DERBY. | ||