Patent EP0227003A2 successfully refreshed from Google Patents.
EP0227003A2
Expired / Lapsed
EP
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Measuring friction characteristics of vehicle travel surfaces
Assignee: K J LAW ENGINEERS Inc
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Filing: 1986-12-16
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Granted: —
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Expires: 2006-12-16
Abstract
Abstract Apparatus for measuring friction characteristics of a vehicle-travelled surface comprising a wheeled vehicle (12) having a test wheel assembly (24) pivotally suspended therefrom by a parallelogram suspension arrangement. The test wheel assembly includes a test wheel (26) carried by a drive shaft (130) which is driven at predetermined slip by a differential (16) coupled to the vehicle wheels (14). A gear chain (142) extends from the differential (16) to the drive shaft (130) through a housing which forms one arm of the suspension. The second arm is formed by a rod which extends from the differential to one section of a two-axis strain gage wheel force transducer (30) at the test wheel assembly. The differential (16) is suspended by parallel struts (19) from the vehicle frame. A positive displacement pump (58) is coupled to the differential for placing a film of water beneath the test wheel having a thickness which is independent of vehicle speed. The pump and test wheel are clutch driven.
Inventors
- 👤 James W. Strong
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 08:48
CPC Classifications
G; G01; G01N; G01N19/00; G01N19/02
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
232 words
Apparatus for measuring a friction characteristic of a vehicle-travelled surface comprising: a wheeled vehicle constructed to be propelled in a predetermined direction along a travelled surface whose friction characteristic is to be measured; a test wheel assembly including a test wheel, hub means mounting said test wheel for rotation about a test wheel axis and transducer means coupled to said hub means for measuring forces on said test wheel at predetermined orientation to said wheel axis; drive means coupled to at least one wheel of said vehicle and to said test wheel for driving said test wheel at predetermined slip with respect to said at least one vehicle wheel; first suspension means mounting said drive means to said vehicle; second suspension means mounting said test wheel assembly to said vehicle for pivotal motion at an angle to said predetermined direction into and out of engagement with the travelled surface; and means responsive to said transducer means for indicating said friction characteristic; characterized in that said first suspension means comprises means mounting said drive means against rotation with respect to the axis of rotation of said at least one wheel, and in that said second suspension means comprises means for mounting said transducer means against rotation about said test wheel axis so as to maintain said predetermined orientation of said transducer means to said wheel axis during pivotal motion of said wheel assembly.
Claim 2
Dependent Claim
232 words
Apparatus for measuring a friction characteristic of a vehicle-travelled surface comprising: a wheeled vehicle constructed to be propelled in a predetermined direction along a travelled surface whose friction characteristic is to be measured; a test wheel assembly including a test wheel, hub means mounting said test wheel for rotation about a test wheel axis and transducer means coupled to said hub means for measuring forces on said test wheel at predetermined orientation to said wheel axis; drive means coupled to at least one wheel of said vehicle and to said test wheel for driving said test wheel at predetermined slip with respect to said at least one vehicle wheel; first suspension means mounting said drive means to said vehicle; second suspension means mounting said test wheel assembly to said vehicle for pivotal motion at an angle to said predetermined direction into and out of engagement with the travelled surface; and means responsive to said transducer means for indicating said friction characteristic; characterized in that said first suspension means comprises means mounting said drive means against rotation with respect to the axis of rotation of said at least one wheel, and in that said second suspension means comprises means for mounting said transducer means against rotation about said test wheel axis so as to maintain said predetermined orientation of said transducer means to said wheel axis during pivotal motion of said wheel assembly.
Claim 3
Dependent Claim
22 words
The apparatus set forth in claim 1 wherein said first and second suspension means respectively comprise first and second parallelogram suspension means.
Claim 4
Dependent Claim
34 words
The apparatus set forth in claim 2 wherein said first parallelogram suspension means comprises a first pair of parallel strut means pivotally coupled at opposed ends to said vehicle and to said drive means.
Claim 5
Dependent Claim
36 words
The apparatus set forth in claim 3 wherein said second parallelogram suspension means comprises a second pair of parallel strut means pivotally coupled at opposed ends to said drive means and to said test wheel assembly.
Claim 6
Dependent Claim
73 words
The apparatus set forth in claim 4 wherein said vehicle comprises two wheels on a common axis; wherein said drive means comprises differential means coupled to said two vehicle wheels and endless gear drive means coupled from said differential means to said wheel assembly for driving said test wheel; and wherein said second pair of strut means comprises a housing enclosing said gear drive means and a control arm parallel to said housing.
Claim 7
Dependent Claim
25 words
The apparatus set forth in claim 5 wherein said vehicle comprises a self-propelled vehicle, said two vehicle wheels comprising rear wheels of said self-propelled vehicle.
Claim 8
Dependent Claim
125 words
The apparatus set forth in claim 6 wherein said hub means has a central hub axis; wherein said test wheel assembly further includes a test wheel drive shaft coupled to said drive means and mounted for rotation within said hub means; and wherein said transducer means includes a first section mounted to said hub means for rotation about said hub axis, said control arm being pivotally coupled to said first portion, a second portion spaced from said hub and including means rotatably supporting said drive shaft within said second portion, and strain gage means rigidly coupled between said first and second portions for measuring said forces on said test wheel as a function of motion of said second portion with respect to said first portion.
Claim 9
Dependent Claim
64 words
The apparatus set forth in claim 7 wherein said drive means comprises an internally splined collar coupled to said gear drive means, and means forming crowned external splines on said shaft within said collar for maintaining a lever arm of substantially constant length from said drive means to said transducer means for tilting motion of said drive shaft with respect to said hub means.
Claim 10
Dependent Claim
48 words
The apparatus set forth in claim 8 wherein said transducer means comprises strain gage transducing means for separately measuring horizontal forces on said test wheel in said direction of travel, and vertical forces on said test wheel perpendicualr to said direction of travel and to the travel surface.
Claim 11
Dependent Claim
48 words
The apparatus set forth in claim 7 further comprising an electric winch carried by said vehicle and coupled to said test wheel, and means responsive to a vehicle operator and coupled to said winch for selectively raising and lowering said test wheel with respect to the travel surface.
Claim 12
Dependent Claim
40 words
The apparatus set forth in claim 7 wherein said drive means further comprises first clutch means, and means connected to said first clutch means and responsive to a vehicle operator for selectively coupling said test wheel to said drive means.
Claim 13
Dependent Claim
47 words
The apparatus set forth in claim 11 further comprising means including a positive displacement pump carried by said vehicle and coupled to said differential means for directing a film of water of substantially uniform thickness independent of vehicle speed onto the travel surface beneath said test wheel.
Claim 14
Dependent Claim
38 words
The apparatus set forth in claim 12 wherein said pump-including means comprises second clutch means, and means responsive to a vehicle operator and connected to said second clutch means for selectively coupling said pump to said differential means.
References Cited (Backward Citations)
No citation records indexed.
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