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).
Test report on chassis vibration issues, comparing results from different cars and test setups.
Identifier | ExFiles\Box 3\1\ 01-page084 | |
Date | 27th May 1928 | |
-3- 9 Tested on 1718 chassis with & without frame struts. No. difference. I have tested 6 different hours by running them on this rig and the general result if that they are all the same speed, the speed of the periods come on & go off varies about 30 or 40 revs on some cars, 2396 is the worst specimen but a standard chassis which I got from Mr. Platford was very little better. The low speed vibrations which come on on cars with the throttle open are always about the same in intensity on some cars there is a lower period which comes on from 490 to 520 revs. it is only there with the throttle open, it is these low speed periods which shake the lamp & odd fittings on a car. In 3 of the cars I tried, the high speed vibrations were much less but there was something then at the speed. On Mr. Northey's car, we can get over the effect of the vibration, that is the body booms by disconnecting the body from the dashboard, this makes all the difference to the comfort of riding in the car, there is still a further slight improvement by fixing rubber between the frame and the body but it is disconnecting the dash that makes the real improvement. This is what I suggest doing to make Mr. Northey's car fit for trial runs and so that he can have it back, it is no further use to us as regards investigating as we can get it on any car. I think the vibrations which was on 10A9 our last year was the same as we are now investigating. The dashboard is an excellent transmitter of the vibration because it is so stiff torsionally that is why the windscreen made a difference, it was the effect which was removed. On a bare chassis it is very difficult to pick out this period on the road, unless one is looking for it. Another point is the experimental car we have with an enclosed body similar to Mr. Northey's was not nearly so bad, this we found was due to the scuttl having worked loose upon the dash, it has always been a trouble to keep it tight, when it was made tight the booming came on badly. FURTHER TESTS. When we found that the vibration was effected by jacking up the frame, we transferred our experiment to the test plate, we got a chassis & fixed parallel with the test engine & got both engines warm and then fitted a 3" belt round both flywheels, the car could then drive the test engine comfortably. Test No. Condition Result. 1. Standard engine throttle open & closed & plugs out. We got the same results as on the chassis only the periods were very slight, they were the same kind, at about the same speed & were affected by opening & closing the throttle the same. | ||