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).
Analysis and troubleshooting report on damper performance, oil loss, and component wear.
| Identifier | WestWitteringFiles\W\May1931-August1931\ Scan099 | |
| Date | 20th April 1931 guessed | |
| -8- Two holes .038 dia. drilled in each H.P. Valve. Cast Iron Pistons. Nitralloy Wearing Pads. Oiling scheme to connecting links G.L.490-N.S.3192. Loading set - H.P. 120.lbs. L.P. 110.lbs. We have not been able to detect any knock from either damper up to the present mileage. We have had a slight loss of oil which has been cured from the joints of the N.S. damper. We have located one definite trouble. We dismantled the dampers at 5,000 miles to increase the poundage. We found that when the lever was pushed up and then down, a free movement occurred, the oil not filling the cylinder quick enough. This did not happen the reverse way. It produced a dull thud as the piston hit the oil. Mr.Brock showed me a similar case prior to coming out here, with the old type damper. We found in our case that the replenishing ball valve in the aluminium cylinder end was the cause of the trouble. The ball hammers into the aluminium seating to such an extent that it restricts the passage of the oil. We were able to overcome this in two ways. On one damper we re-cut the seating, the other we lifted the restricting screw .050", both these methods cured the trouble. The seating of the replenishing ball valve in the cast iron end was, and has remained without showing any hammering taking place. We would suggest that a steel insert for the seating of the one that hammers would overcome the trouble. We dismantled the O.S. rear damper completely at 10,000 miles. The condition was a considerable improvement over any other damper previously dismantled. There was an absence of the aluminium in the oil which has always been a feature of previous dampers. The piston and cylinder bore showed no traces of scoring. The lever where it comes in contact with the pads was slightly scored, and at one side, slight wear had taken place when the pad had not been in full contact. The pads showed bright markings of contacts, the wear was negligible. The high and low pressure valves and their seatings were in a very good condition. The poundage has remained consistent. We have had a failure with the lubrication of the shock damper connecting links. This is now fed the link. The cause was, stones had hit the Bijur lubricating pipe which caused the joints to become loose and oil escaping left the top pads dry. We tightened these joints up very firmly, and have not since had any trouble. They are however too exposed for safety. We stopped the .038 holes up in the high pressure valves, midway through the test, to procure steadier riding of the car. | ||