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).
Modifications to a dynamo coupling to reduce oscillation amplitude and uneven wear.
Identifier | ExFiles\Box 136\1\ scan0301 | |
Date | 11th July 1938 | |
-2- Rm{William Robotham - Chief Engineer}/Sedl.2/MR.11.7.38. The results obtained as given on the attached curve shows the maximum amplitude of .4° at 3800 r.p.m. with standard conditions reduced to .1° at the same speed by the above modifications. In view of this we should like to have a modified design of dynamo coupling giving increased flexibility, which can be finally settled by different durometer hardness of the rubbers. The existing design allows little scope for increased flexibility due to the small dimensions of the rubbers and the large dimension of the centre steel pins. Regarding the increased inertia ring we fitted to the cam-wheel, this increased the original Fabroil camwheel inertia 125% the total now in lbs.ins.² units being .086. We should like a J2.2 x 12 design for this if it is proved from 15,000 miles road tests that the above modifications do clear us of the uneven wear trouble. Additional to the above we have tried different dynamo drive shaft dimensions which with standard rubbers move about the peak of oscillations, viz. .3 dia. shaft - 3100 r.p.m., .4 dia. shaft (standard) - 3800 r.p.m. and .562 dia. shaft - 4300 to 4400 r.p.m. The stiffer the shaft the higher the peak and amplitude due to the increasing inertia of the dynamo etc. with speed. With very flexible coupling rubbers there is little to choose between any shaft as registered on the camshaft oscillations. Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} | ||