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).
Comparing the performance and failure risks of hydraulic versus Hartford shock dampers.
| Identifier | ExFiles\Box 55\3\ Scan159 | |
| Date | 4th May 1926 | |
| To R. {Sir Henry Royce} from Hs {Lord Ernest Hives - Chair} /Rm. {William Robotham - Chief Engineer} c. to BJ. RG. {Mr Rowledge} c. to E. {Mr Elliott - Chief Engineer} DA. {Bernard Day - Chassis Design} c. to EY. Na. {Mr Nadin} c. to Wor. {Arthur Wormald - General Works Manager} X235 Hs {Lord Ernest Hives - Chair} /Rml/LG4.5.26. HYDRAULIC SHOCK DAMPERS. X235 XH476 We observe that the allowable movement of the rear axle from maximum bump to maximum rebound with the hydraulic shock dampers is considerably less than that available with Hartford shock absorbers. When the Hartford shock absorbers are extended the movement from maximum bump to maximum rebound is 16.7". The hydraulic damper with the 14" lever gives only 14.2". The hydraulic damper with the 13" lever to N.sch.2182 gives only 13.2". We know that at the present time it is quite possible to turn Hartford shock absorbers inside-out or smash them when going over a bump at speed. We consider that this is still more likely to happen as we fit more flexible rear springs. Within the last few days we have EX broken by extension, a Hartford shock absorber on 10-EX - the rear weight of this car is 1 ton. 2 cwts. empty, and the springs fitted are 1700 and 1800 lbs. The increase in piston travel on the hydraulic damper with the 14" lever in order to give the same travel as the Hartford is .156" each end. We consider that when a rear shock damper is smashed on a fast car such as 10-EX there is very considerable risk of an accident following. On the recent occasion which we quote, the driver was unaware that one of his rear shock dampers had failed and almost immediately afterwards had occasion to swerve to avoid an obstruction. contd :- | ||