Abstract:
A MACHINE HAS BEEN BUILT TO MEASURE IN THE LABORATORY THE FOLLOWING CHARACTERISTICS OF IRON PAVING BLOCKS: (1) THE COEFFICIENT OF FRICTION BETWEEN THE PAVING BLOCKS AND RUBBER TIRES FOR STRAIGHT SKIDDING AND FOR SIDEWAYS SKIDDING, (2) THE STOPPING DISTANCE OF A CAR ON SUCH A PAVEMENT, AND (3) THE TIRE NOISE. THE MACHINE CONSISTS OF TWO SIX-FOOT FLYWHEELS, ON THE PERIPHERY OF WHICH ARE BOLTED THE PAVING PLATES TO BE TESTED. AN AUTOMOBILE IS MOUNTED SUCH THAT ITS FRONT WHEELS REST ON THESE FLYWHEELS. THE FLYWHEELS ARE ROTATED BY A 15 HORSEPOWER MOTOR TO TOP PERIPHERAL SPEEDS OF 60 MILES PER HOUR. HYDRAULIC TRACTION DYNAMOMETERS ARE CONNECTED TO THE CENTER OF GRAVITY OF THE CAR AND SERVE TO MEASURE THE BRAKING FORCE AND THE SIDEWAYS FORCE WHEN THE BRAKES ARE APPLIED OR WHEN THE FRONT CAR WHEELS ARE TURNED THROUGH AN ANGLE. A HIGH-SPEED MOTION PICTURE CAMERA IS USED TO RECORD THE DYNAMOMETER READINGS, THE TIME, AND THE MOTION OF THE FLYWHEELS AND OF THE FRONT CAR WHEELS. EXAMPLES OF THE CURVES SO OBTAINED ARE GIVEN. IT HAS BEEN FOUND THAT BY CHANGING THE DESIGN OF THE SURFACE PAVEMENT CORRUGATIONS, THE COEFFICIENT OF FRICTION MAY BE CHANGED BY MORE THAN 100 PER CENT. /AUTHOR/
Supplemental Notes:
Vol 17, ParT I, PP 136-143, 3 FIG, 1 TAB, 4 PHOT. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved.
