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).
Letter to Gordon Armstrong regarding the failure of their shock absorbers during testing and suggesting design improvements.
| Identifier | ExFiles\Box 152\1\ scan0210 | |
| Date | 7th December 1936 | |
| 1293 Experimental Department 7th December 1936. Rm {William Robotham - Chief Engineer} /Les.15/AP. The Gordon Armstrong Patent Suspension Co.Ltd., Waltham Works, BEVERLEY E.Yorks. Dear Mr.Armstrong, We have tested your shock absorbers until the shafts have twisted off at the undercut at the end of the serrations. Unfortunately, on our bumper rig they only had a very short life. One shaft broke after 4 minutes, the other at 4½ minutes. We generally get shock absorbers to last 100 hours on the bumper before going on to Production. The cause of the failures appeared to be due to the high maximum load from a variable leak orifice damper compared to the strength of the shaft. A spring loaded valve is much kinder to the damper. However, we shall have to increase the strength of the shaft. Can we get an 1¼" diameter shaft between the main lever and the intermediate lever.? We use 1⅛" diameter shaft. At the moment we use the same shock absorber on Ph.III. and Bentley. For Bentley it is obviously too strong and heavy, so that as long as the damper is impossible to break we do not want to go to your next size in damper. I should like to hear what you think can be done in the way of a larger shaft for your present shock absorber. If you like we can make the shafts and necessary cutters for the serrations. Alternately we shall be ready to pay for them. We are still very keen to make these shock absorbers a success, but even when using spring loaded valves the damper has to be made sufficiently strong for cases where the valve sticks. So far we have been unable to produce a spring loaded valve which is quiet and can deal with sufficient load without a possibility of sticking. contd | ||