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 investigation of vertical body shake, detailing tests on a vibrator rig and the effectiveness of fitting stiffening plates.
| Identifier | ExFiles\Box 112\1\ scan0107 | |
| Date | 8th December 1938 | |
| Handwritten: file Handwritten: 346 To By.{R.W. Bailey - Chief Engineer} from RM{William Robotham - Chief Engineer}/AFM.{Anthony F. Martindale} c. Da.{Bernard Day - Chassis Design} c. Da{Bernard Day - Chassis Design}/DB.{Donald Bastow - Suspensions} c. By/Mr. Bower. BODY SHAKE - 1.B.50. This car has an objectionable body shake on indifferent roads, chiefly at the front end of the body. This shake is peculiar to this car, and is not a sideways shake but is vertical. On the vibrator rig it appeared that the front end of the frame bent at a point just behind the torque arm rear end socket, where the frame is weak. While the car was vibrating there was considerable vertical movement of the radiator cap, whereas the body was apparently still; the angle between bonnet and body appeared to vary. We fitted stiffening plates to the side of the frame as in diagram (1). The result was that on the vibrator rig relative movement between body and radiator was reduced (see diagram (2) and this modification stopped the objectionable shake on the road. Tests have been made with body mountings solid and floating, (giving four combinations of body mountings and stiffening plates) and although the solid mounting reduces the shake it is not as effective as the plates and it brings up body noise. We have measured the extra stiffness both in torsion and bending that the side plates give (see Figs. 3 and 4). The torsion tests were taken in the ordinary way, and the bending tests were taken with each end of the car resting on supports on the axle centres, measurements of the sagging deflection of the frame being taken. It may be remarked that the decrease of deflection shown on Graph 4 seems only a small proportion and unlikely to affect the behaviour of a car on the road. The calculation, Fig. 5, indicates that doubling the stiffness of one end of a beam reduces the deflection, in the same proportion as adding the side plates actually did to the car; or in other words, the stiffness increase should materially affect local deflection due to vibration. | ||