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).
The performance, wear, and modifications of various damper designs and materials.
| Identifier | ExFiles\Box 152\2\ scan0004 | |
| Date | 6th July 1937 | |
| -3- (c) Nickel steel, hobbed .812" diameter shafts. (d) Double spring loaded valves. These dampers remained quiet and were absolutely free from oil leaks. The oil was still up to the correct level (3/8" from the top of the casing) at the end of the mileage. The loads were originally set at 80 lbs. In France the loads were increased to 120 lbs, but owing to wear taking place between the shaft and the valve spring plunger the damper loads at the end of the mileage had decreased to N.S. 60 and O.S. 70 lbs. The wear was the result of high pressure oil forcing the plunger in contact with the shaft. All other parts of these dampers were in very good condition. The size of the bearings at the end of the mileage were- Bore Shaft Clearance. N.S. Large bearing............ .8142 .812 .0022 Small bearing............ .6909 .687 .0039 O.S. Large bearing............ .8137 .8125 .0012 Small bearing............ .690 .6871 .0029 We have run a pair of Armstrong dampers with .010" bearing clearance and have been unable to detect any noise on the road. (5) A new pair of dampers were received having- (a) Aluminium sand cast casings instead of Mazak die castings. (b) R.R. standard damper valve with bellows control Fig.II. (c) 1 1/8" diameter shafts instead of 0.812" diam. These dampers suffered very badly from loss of load after fast movements, which was the result from pressure building up in the operating part of the damper. The pressure 'build up' is due to the slightly uneven displacements of the two pistons. On our present dampers we have grooves in the top of the pistons to prevent 'build up'. On these Armstrong dampers it was found that the size of leak to the reservoir required to prevent 'build up', was far too large for road conditions. continued | ||