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).
Experiments on a centrifugally loaded autofriction vibration damper and spring drive to address gear rattles and master period issues.
| Identifier | ExFiles\Box 179\3\ img140 | |
| Date | 1st April 1932 | |
| ORIGINAL R.{Sir Henry Royce} From He/Gry.{Shadwell Grylls} c. to Rg.{Mr Rowledge} Mor. c. to E.{Mr Elliott - Chief Engineer} By.{R.W. Bailey - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} He/Gry.{Shadwell Grylls}9/AL.1. 4. 32. x634 x7020 VIBRATION DAMPER AND SPRING DRIVE P.II. We have recently carried out further experiments on the autofriction centrifugally loaded damper (Led.2739). We did this because the present low inertia spring drive is unsatisfactory in two ways. First, with sufficient damping to overcome the half torsional period gear rattles are present with the high lift camshafts. A slight increase in damping load makes the rattle very prominent. Secondly it is entirely inadequate for the master period. Our experiments have been therefore an endeavour to damp out the master period without bringing up gear rattles. To make our experiments easier we reduced the master period to 3000 R.P.M. by fitting balance weights balancing all the centrifugal forces. Our experiments were done on 3rd gear so that we started with a top period at 60 M.P.H. in this gear. (1) With plunger springs giving a static damping load of 6 lbs at 17+" and 12 full size aluminium plungers there was no half period but the top period was too bad to drive through and would most probably have broken the crankshaft. The engine began to get rough 500 R.P.M. below the top period. (2) Steel plungers were fitted giving a calculated damping load at 3000 R.P.M. of 71 lbs at 17+". There was still no half period although we expected one due to the damper being solid. We could then drive through the master period which however was still very violent on the overrun. The period again began at 2500 R.P.M. but ended sharply at 3100 R.P.M. the engine being very smooth at higher speeds. (3) We made use of the torsional driving shaft and a heavy steel fan pulley to give us an additional Buick type damper. The crankshaft pinion we drove temporarily by rubber blocks from the fixed part of the damper hub. The additional damper was tuned to twice crankshaft frequency. The effect was to split up the top period into two at 50 and 70 M.P.H. in 3rd. These in conjunction with the autofriction damper are barely noticeable on the drive but on the overrun are still unpleasant, the lower period being the worse | ||