Referring to
The base frame 1 can be steadily positioned on the floor, having a front upright tube 10 on the middle of the front side and a horizontal locating frame bar 11 perpendicularly and fixedly connected to the front upright tube 10 and horizontally extending toward the rear side. The two pedal frames 2 each have a coupling rod 21 respectively pivotally connected to the front upright tube 10 of the base frame 1 at two sides. The coupling rod 21 of each pedal frame 2 has a lug 22. Further, each pedal frame 2 holds a respective pedal 20. The friction wheel 4 is coupled between the free end of the horizontal locating frame bar 11 and a rear part of the base frame 1, having a traction plate 41 disposed at the top side. The two links 3 are respectively coupled between the two distal ends of the traction plate 41 and the lugs 22 at the coupling rods 21 of the pedal frames 2. The adjustment rod 5 is rotatably mounted in the base frame 1, having a friction block 50 disposed in contact with the friction wheel 4. By means of rotating the adjustment rod 5 clockwise or counter-clockwise, the friction resistance between the friction wheel 4 and the friction block 50 is relatively adjusted. Further, each link 3 has an adjustment nut 30 on the middle. By means of rotating the adjustment unit 30, the length of the respective link 3 is relatively adjusted.
When in use, the base frame 1 of the stepper is placed on the floor, and then the adjustment nuts 30 are respectively rotated to adjust the length of the links 3 so as to further adjust the elevation of the pedals 20 and the oscillation amplitude of the pedal frames 2, and then rotate the adjustment rod 5 to adjust the friction resistance between the friction wheel 4 and the friction block 50, i.e., to adjust the damping resistance to the pedal frames 2. When stepping one pedal 20 with force to lower the associating pedal frame 2, the associating coupling rod 21 is biased relative to the front upright tube 10 to pull the associating link 3 and to further rotate the friction wheel 4 in one direction through a predetermined angle, thereby causing the other pedal frame 2 to be lifted. Therefore, when the user is stepping the pedals 20, the pedal frames 2 are alternatively moved up and down.
Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.