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).
Torsional vibration tests performed on B.60 chain drive units with various dampers.
| Identifier | ExFiles\Box 124\1\ scan0267 | |
| Date | 27th November 1939 | |
| To Ev.{Ivan Evernden - coachwork} c. to Jnr.{Charles L. Jenner} RM{William Robotham - Chief Engineer}/JRS.12/JH.27.11.39. TORSIONAL VIBRATION TEST ON B.60 CHAIN DRIVE UNITS. Torsiograph records were obtained from B.60 No.1 chain drive unit with both the B.60 damper and the Studebaker damper, and from B.60 No.3 with the Humber snipe damper. Various torsional stiffnesses were experimented with on the B.60 damper and the optimum settings of the Studebaker and Humber dampers were found by using various rubber cones and friction torque values respectively. For reference the curve for B.60 No.3 gear drive unit with the B.60 damper at its best stiffness value is shown. As expected the best setting of the B.60 damper was found to be the same for the chain drive as for the gear, This is when the torsional stiffness is 210 pounds feet/degree. The best results were obtained with the Studebaker damper when the 45 - 50 durometer hardness rubbers were used and with the Humber when the friction torque was 50 pound inches. Of the curves shown there is no outstanding difference. The best overall result is given by the Studebaker damper which gives the lowest values over practically the full range. Of the others the Humber snipe damper is probably the best but there is not much advantage. Extra friction discs were ordered for this damper, of bakelised fabric but these were not used due to the fact that when testing the torque the damper seized if the arm were moved quickly. I understand that this type of friction discs has previously been abandoned on the Wraith spring drive for the same reason. When the chain and wheels were observed by the stroboscope a large vibratory movement was observed in the region of 2700 r.p.m. Cont'd.{John DeLooze - Company Secretary} | ||