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 analysis of Borg & Beck 10' and 11' spring driven clutch plates.
Identifier | ExFiles\Box 130\3\ scan0092 | |
Date | 16th June 1939 | |
1110 To Da.{Bernard Day - Chassis Design} c. to Hdy.{William Hardy} Rm{William Robotham - Chief Engineer}/WRC.5/JH.16.6.39. BORG & BECK DRIVEN PLATES. The spring drives in the hubs of the 10" and 11" plates are identical except for a small difference in the strength of the springs, and this is arranged by altering the free length. The 10" plate has 8 springs (Red) of nominally 1.073 free length, and the 11" has 8 springs (Yellow) of nominally 1.087 free length, both acting at 2.125 radius. The angular displacement of the hub is limited by stops to approx. 4° either side of zero. The rate of each spring is approx. 1000 lbs/per inch. (mean of four actually tested). The springs are approaching solid length when the stops limit further movement. The torque necessary to produce maximum deflection approx. 186 lbs.ft. for the 10" plate, and 205 for the 11" (omitting the effect of the damping friction). The springs have a small pre-load when at rest (no torque), and the torque necessary to start movement is about 68 and 75 lbs. respectively, but this figure is liable to considerable variation on account of the very high rate of the springs and their variation in free length (the ends of the springs are roughly finished). From the above, the following conclusions are drawn :- (1) The 10" clutch on the 4¼ litre 6 cyl. engine, with a torque of about 200 lbs.ft. would be running chock at max. torque. (2) The 11" clutch as above, would be on the threshold of running chock. (3) The 11" clutch with a 5.7 litre 6 cyl. engine would become chock at round about 2/3 of max. torque. NOTE. Borg & Beck fit these spring drive hubs to most of their | ||