Exercise devices – Involving user translation or physical simulation thereof – Treadmill for foot travel
Reexamination Certificate
2002-05-07
2004-06-01
Richman, Glenn E. (Department: 3764)
Exercise devices
Involving user translation or physical simulation thereof
Treadmill for foot travel
C482S051000
Reexamination Certificate
active
06743155
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an angle-adjusting device for a treadmill frame, and more particularly to an angle-adjusting device that makes the treadmill stable and vibrate less during operation.
2. Description of Related Art
With reference to
FIG. 6
, a conventional angle-adjusting device (
50
) for a treadmill frame in accordance with the prior art is adapted to be secured under the rear end of a treadmill. The treadmill (
40
) includes a front supporting lever (
41
), an erect handgrip frame (
42
), a belt frame (
43
), a traveling belt (
45
) and the angle adjusting device (
50
). The angle-adjusting device (
50
) is composed of a pair of polygonal feet (
51
) respectively mounted on opposite sides of the bottom of the rear portion of the belt frame (
43
). The polygonal feet (
51
) are triangular. The polygonal feet (
51
) are respectively rotatably mounted on opposite ends of a connecting rod (
46
).
Each polygonal foot (
51
) has multiple ground contact edges (not numbered), and each edge is a different length from the other edges so when any ground contact edge of the polygonal plate (
51
) contacts the ground, the sloping angle of the belt frame (
43
) is changed. Furthermore, changing the sloping angle of the belt frame (
43
) only requires raising the belt frame (
43
) to allow the ground contact edge of each polygonal plate (
51
) to be lifted clear of the ground. Thereafter, the two polygonal feet (
51
) are rotated on the connecting rod (
46
) to permit another ground contact edge to be parallel to the ground. Since the ground contact edge of the polygonal plate is changed, the sloping angle of the belt frame (
43
) can be easily changed to meet different requirements.
However, the conventional angle-adjusting device (
50
) is not directly secured on the belt frame (
43
), and a “linkage,” as show in
FIG. 7
, is formed between the angle-adjusting device (
50
) and the belt frame (
43
) in mechanics. The treadmill having a conventional angle-adjusting device (
50
) constitutes three links of a quaternary link, wherein the four links of the quaternary link are the angle adjusting device (
50
), the belt frame (
43
), the front supporting lever (
41
), and the ground. Stability of this linkage can be estimated by the Kutzbach formula:
F=
3(
N−
1)−2
P
Wherein F is the degree of freedom of the kinematic chain;
N is the number of links; and
P is the number of pairs of elements.
Where N=4 and P=4 for the conventional quaternary link, F is 1. When F is positive, the kinetic chain being analyzed is under-constrained (i.e. moveable) according to the Kutzbach formula. Since F is positive for this quaternary link, the treadmill is unstable and will vibrate when someone steps or runs on the structure.
The present invention has arisen to mitigate and/or obviate the disadvantages of the conventional angle-adjusting device.
SUMMARY OF THE INVENTION
A main objective of the angle-adjusting device in accordance with the present invention is to make the treadmill stable during operation.
Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.
REFERENCES:
patent: 6171216 (2001-01-01), Wang et al.
Forhouse Corporation
Head Johnson & Kachigian
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