COMPARABILITY OF TYRE-ROAD ADHESION COEFFICIENTS

VERGLEICHBARKEIT VON KRAFTSCHLUSSBEIWERTEN

IN THE FUTURE IT IS TO BE EXPECTED THAT VEHICLES WITH AUTOMATIC ANTI LOCKING DEVICES WILL PARTICIPATE IN ROAD TRAFFIC. AS THE WHEELS OF THESE VEHICLES CANNOT LOCK DURING BRAKING, THE COEFFICIENT OF SLIDING IS NOT A SUFFICIENT CRITERION FOR EVALUATING THE TYRE-ROAD ADHESION BETWEEN VEHICLE AND CARRIAGEWAY. IT IS THEREFORE NECESSARY TO BE ABLE TO MEASURE TYRE-ROAD ADHESION COEFFICIENTS FOR THE NON-LOCKED MEASURING WHEEL UNDER DEFINED SLIP. WITH THE UNIVERSAL FRICTION METER IT IS POSSIBLE TO FORCE THE MEASURING WHEEL INTO POSITIVE AND NEGATIVE SLIP. THUS, FOR EXAMPLE, GIVEN A DRIVING SPEED OF 80 KM/H THE MEASURING WHEEL CAN BE DRIVEN AGAINST THE DIRECTION OF TRAVEL AT 40 KM/H. THEREFORE IT IS POSSIBLE THEORETICALLY TO DETERMINE THE COEFFICIENT OF SLIDING FOR 120 KM/H FROM A RELATIVE CONSIDERATION, AND THIS HAS NOT BEEN POSSIBLE HITHERTO THROUGH SKIDDING RESISTANCE MEASUREMENTS AT DRIVING SPEEDS OVER 100 KM/H. CARRIAGEWAY SLIPPERINESS ON BENDS OR ON GRADIENTS OR IN MOVING TRAFFIC COULD BE DETERMINED WITHOUT HINDERING OTHER VEHICLES IF ONE ADJUSTS TO DEFINED BRAKING SLIP VALUES. THE AIM OF THE RESEARCH IS TO DETERMINE A RELATION BETWEEN THE ADHESION COEFFICIENTS ESTABLISHED AND THE SKIDDING RESISTANCE VALUES OF THE BLOCKED SLIP WHEEL. BY COMPARING ADHESION VALUES DETERMINED IN VARIOUS WAYS ONE CAN WORK OUT PRINCIPLES FOR EVALUATING ROADS WHICH ARE STRESSED BY MODERN VEHICLES.