| 摘要 |
The pedalling action drives a drive axle which is positioned below the back support. A wheel is eccentrically positioned on the drive axle and acts as a cam to drive the back support in its repeated pivoting motion. Roller bearings are positioned on the underneath side of the back support and engage the eccentric wheel (cam), thereby reducing friction between the rotating wheel and the pivoting back support during the sit up cycle.
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