Measuring and testing – Frictional resistance – coefficient or characteristics
Patent
1989-01-03
1990-09-11
Williams, Hezron E.
Measuring and testing
Frictional resistance, coefficient or characteristics
73146, G01N 1902
Patent
active
049559338
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
In the prior art there is known, from German published specification DE 852 161, a device for measuring the friction on a suface, wherein the first shaft moves a pair of wheels interconnected by means of an axis, which pair of wheels in turn move the measuring wheel by intermediation of another shaft. The second shaft, attached to the measuring wheel, is wound around the axis of the pair of wheels. In between the measuring wheel and the second shaft there is provided a spring, which retards the measuring wheel while the device is being moved. The degree of rotation of the measuring wheel at a point where the wheel starts to slide is comparable to the friction between the wheel and the base. The purpose of the pair of wheels is to make the attractive force directed to the measuring wheel parallel to the horizontal level, and it receives the vertical force component directed to the device due to the pulling.
The above described device is relatively large in size and is composed of several different components. Thus it is fairly sensitive to damage for instance during transport.
SUMMARY OF THE INVENTION
The object of the present invention is to simplify and to improve the device of the above described type in order to measure the friction on a surface. The device comprises a measuring wheel that is mounted for rotation about an axis and an arm is attached to the axis. A spring is connected between the measuring wheel and its axis and is arranged to resist rotation of the wheel when the wheel is moved on a surface to be measured by a handle attached to the arm.
Among the advantages of the measuring apparatus of the present invention, there is pointed out its simple structure, which means that the device is easy to carry along. Moreover, it is easily maintained, and the manufacturing costs are low.
DESCRIPTION OF THE DRAWINGS
In the following the invention is explained in detail with reference to the appended drawings, where
FIG. 1 is a side-view illustration of the measuring device;
FIG. 2 is a front-view illustration of the measuring device; and
FIG. 3 illustrates the structure of the measuring wheel
DESCRIPTION OF THE ILLUSTRATED EMBODIMENT
In FIGS. 1 and 2, the device of the invention comprises the measuring wheel 1, the arm 2, the measuring wheel axis 3 and the spring 6. The measuring wheel 1 is free to rotate around its axis 3. The arm 2 is attached to the axis 3. The spring 6 is attached in between the measuring wheel 1 and its axis 3. The spring 6 is arranged to resist the rotation of the measuring wheel 1, when the measuring wheel 1 is moved by the arm 2 during the measuring operation on the surface 5 under measurement.
The arm 2 is stiff and uniform. At its first end 2a there is provided a straight part 8, which is permanently attached to the axis 2. At the second end 2b of the arm 1 there is provided the pull handle 4 or a corresponding member. The arm 2 is provided with an inclination indicator 9. In the measuring position, the angle of inclination .alpha. of the arm 2 is maintained, with respect to the surface 5 under operation, and the pull handle 4 is kept at a further distance than the radius R of the measuring wheel with respect to the surface 5. In order to help maintain the angle .alpha. of inclination constant, the arm is bent or folded, and its first part 8 starting from the axis 2 is in the correct position of the arm parallel to the surface 5.
The spring 6 resisting the rotation of the measuring wheel 1 can be attached to the measuring wheel for instance as is illustrated in FIG. 3. In this case the spring 6 is at one end fastened to the pin 10 provided in the measuring wheel, and at the other end to the protruding part 12 of the plate 11 wound around the axis 3. The rotation of the plate 11 can be prevented by means of the screw 13 which is attached to this protruding part 12.
While measuring friction, the measuring wheel 11 is pushed or pulled on the surface 5 under measurement. The rewinding of the measuring wheel is prevented by means of the sprin
REFERENCES:
patent: 2821081 (1958-01-01), Staples
patent: 2946644 (1960-07-01), Henry
patent: 3367170 (1968-02-01), Lynch et al.
patent: 4594878 (1986-06-01), Abe et al.
Roskos Joseph W.
Williams Hezron E.
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