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).
Comparison of the limited travel of hydraulic shock dampers versus Hartford shock absorbers, highlighting the risk of failure at speed.
| Identifier | ExFiles\Box 51\4\ Scan118 | |
| Date | 4th May 1926 | |
| To R. {Sir Henry Royce} from Hs {Lord Ernest Hives - Chair} /An. c.c. to BJ. RG. {Mr Rowledge} c.c. to E. {Mr Elliott - Chief Engineer} DA. {Bernard Day - Chassis Design} c.c. to BY. {R.W. Bailey - Chief Engineer} Na. {Mr Nadin} c. to Wor. {Arthur Wormald - General Works Manager} 44426 Hs {Lord Ernest Hives - Chair} /Anl/LG4.5.26. HYDRAULIC SHOCK DAMPERS. X235 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 had one 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 > | ||