Roadway friction tester and method
First Claim
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1. A method for measuring road surface friction of a road surface using a vehicle that moves across the road surface, which comprises the steps of:
- (a) interposing an auxiliary independent wheel between said vehicle and the road surface, said auxiliary wheel being freely rotatable by movement of said vehicle and being one or more of toed in or toed out with respect to a direction of travel of said vehicle so as to create an isolated axial force on said auxiliary wheel;
(b) measuring the axial force on said auxiliary wheel while said vehicle moves across said road surface; and
(c) correlating said measured axial force with the road surface friction.
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Abstract
A method for measuring road surface friction of a road surface uses a vehicle that moves across the road surface. An auxiliary independent wheel is interposed between the vehicle and the road surface. The auxiliary wheel is freely rotatable by movement of the vehicle and is toed in (skewed) with respect to a direction of travel of the vehicle so as to create an axial force on the auxiliary wheel. The axial force on the auxiliary wheel is isolated and measured while the vehicle moves across the road surface. The measured axial force is correlated with the road surface friction.
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Citations
33 Claims
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1. A method for measuring road surface friction of a road surface using a vehicle that moves across the road surface, which comprises the steps of:
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(a) interposing an auxiliary independent wheel between said vehicle and the road surface, said auxiliary wheel being freely rotatable by movement of said vehicle and being one or more of toed in or toed out with respect to a direction of travel of said vehicle so as to create an isolated axial force on said auxiliary wheel;
(b) measuring the axial force on said auxiliary wheel while said vehicle moves across said road surface; and
(c) correlating said measured axial force with the road surface friction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A device for measuring road surface friction of a road surface using a vehicle that moves across the road surface, which comprises:
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(a) an auxiliary independent wheel interposed between said vehicle and the road surface, said auxiliary wheel being freely rotatable by movement of said vehicle and being one or more of toed in or toed out with respect to a direction of travel of said vehicle so as to create an axial force on said auxiliary wheel;
(b) an axial force sensor mounted with respect to said auxiliary wheel so as to measure the axial force exerted on said auxiliary wheel while said vehicle moves across said road surface; and
(c) a converter for correlating the measured axial force with the road surface friction. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A method for measuring road surface friction, which comprises the steps of:
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(a) providing a vehicle;
(b) mounting an auxiliary wheel to said vehicle, said auxiliary wheel being one or more of toed in or toed out, loaded, and mounted on an axle for its free rolling;
(c) associating a speed device and a calibrated force sensor with said auxiliary wheel to measure the axial force thereon;
(d) moving said vehicle along a road; and
(e) determining the road surface friction based on the speed of said auxiliary wheel and the lateral force exerted on said auxiliary wheel. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25)
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26. In combination, a vehicle and a device affixed to said vehicle, said device for measuring road surface friction, said device comprising:
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(a) an auxiliary wheel mounted to said vehicle, said auxiliary wheel being one or more of toed in or toed out, loaded, and mounted on an axle for its free rolling;
(b) a calibrated force sensor associated with said auxiliary wheel to measure the axial force thereon;
(c) a converter for measuring the road surface friction with said force sensor. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33)
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Specification