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 report on diagnosing causes of knocks and noises in Phantom II and 20 HP models.
| Identifier | ExFiles\Box 16\4\ Scan200 | |
| Date | 25th October 1930 | |
| ) -2- Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}1/MJ.25.10.30.Contd. that the pin becomes uncovered as soon as the oil level falls. This pin wear is perhaps largely responsible for the big percentage of Phantom 11 knocks reported. Slack Connecting Tubes and Balls. - The spring loaded balls are a great improvement on Phantom 11 and have eliminated noise at this point. We are standardising the similar scheme on the 20 HP. The 20 HP. tubes, however, are not reinforced at the ends like those of the 40/50 and we have cases where they have bulged out, allowing the brass pads to knock sideways. We think that they could with advantage be brought in line with the 40/50. Choked Air Vents. - These are occasionally found to be the cause of noisy dampers. To overcome the trouble we suggest a gauze filter over the end of the valve cap carrying the vent. The vent is .024" dia. We are trying a 60 mesh gauze 37 W.G. as the quantity of foreign matter present is small. This will give an aperture of about .010. We are running such filters on our experimental cars. In addition to these three causes, and apart from loss of oil which is dealt with separately, there are occasional cases where a knock is audible in the car when the dampers are apparently 100%. Mr. Pilling's car was the only example we ourselves have dealt with. It is up to us to find out experimentally why this is so, and until we have more information we have no alternative but to treat each case individually by reducing the damper load reversals. further source of trouble is dampers loose in the frame | ||