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).
Analysis of noises produced by tires under various road conditions and test scenarios.
| Identifier | ExFiles\Box 158\1\ scan0129 | |
| Date | 22th January 1934 guessed | |
| -6- In Slide 9 there are 2 - 5.50-17, 4-ply tires, the difference being that Tire 1 has small cross strips or "cross vents" across the grooves. A tire with these cross strips produces a fluttering or low frequency buzzing noise, in addition to the other noise. When these strips are removed, the total noise is reduced altho the fundamental note due to impact may be more noticeable. Tire 1 with the cross strips will now be run at 45 miles per hour, followed by Tire 2 which has no cross strips. Tire 1 - (Eight seconds of tire noise from tire with vents). Tire 2 - (Eight seconds of tire noise from tire without vents). NOISES DUE TO ROAD CONDITIONS: We have not tried to reproduce the noises due to brick pavements or to gravel roads, as they are familiar to everyone. The expansion-joint noise can be shown on the test wheel by adding a small strip of metal to the surface of the wheel as shown in Slide 10. The noise will be heard at each revolution of the test wheel. The wheel will be started at 20 miles per hour and allowed to coast. The tire used in this case is a 7.50-15 with rib tread (Slide 11). The noise is as follows: (7.50-15 rib tread tire at 20 miles per hour, and then coast 12 seconds.) Slide 10 Slide 11 In a car, this type of noise comes first from the front wheels, and then from the rear wheels in rapid succession as the car passes over each joint. For this reason the effect when heard in a car is a double sound, like the word "flip-flop" instead of the single noise shown on the wheel. The noise due to stones in the tread can also be demonstrated on the test wheel. Slide 12 - shows a stone wedged in the tread groove of a 6.50-19, 6-ply tire. The sound of the stone striking the wheel surface can be heard above the usual noise from the tire. The tire will first be run at 20 miles per hour, and then allowed to coast. (6.50-19, with stone, starting 20 miles per hour and coasting for 12 seconds). Slide 12 NOISES DUE TO MOVEMENT OF TREAD IN CONTACT WITH THE ROAD: Noises due to tread movement in contact with the road surface are difficult to distinguish from the impact type of noise in straight-away driving. However, it is possible to prove the existence of such a noise if suitable conditions are selected. The 7.50-15 rib tread tire shown in Slide 11 does not produce impact noise because of the continuous plain ribs. If this tire is run at more than normal deflection, the tread movements in contact with the road are exaggerated, and noise due to such movements becomes noticeable. The tire will first be run at 1160 lbs. load and 24 lbs. inflation to obtain the noise under normal conditions, after which it will be | ||