Patent ID: 7240598

Claim:
A power transmission structure of a circular saw having a seat body with a driving member having a driving shaft driving a circular saw blade, one side of the seat body being provided with a driven shaft, the driven shaft having a pre-cut blade engaged therewith, the pre-cut blade being aligned with the circular saw blade, the power transmission structure being positioned between a driving roller and a driven roller such that the circular saw blade and the pre-cut blade rotate in reverse directions, wherein the driving shaft is locked to a binding mount protruded with a fixing plate facing one side of the driven shaft, and an end of the driving shaft is provided with the driving roller through the binding mount, and a center of the fixing plate is rotatably mounted with a dual level transmission roller, and two side corners of the fixing plate are respectively rotatably connected with a steering roller and a steered roller, and the driving roller of the driving shaft, the steering roller, the steered roller and a front section of the dual level transmission roller are engaged with a first transmission belt, the first transmission belt surrounds an inner edge of the dual level transmission roller such that the dual level transmission roller and the driving roller rotate in reverse directions, the end of the driven shaft opposite to the end engaging the pre-cut blade is provided with the driven roller, and a center of a bottom edge of the fixing plate is pivotally mounted with a floating rod, and a free end of the floating rod is provided with an adjusting roller, and a traction spring is mounted to a middle section of the floating rod to pivotally bias the floating rod, and the driven roller, the adjusting roller and the dual level transmission roller are engaged with a second transmission belt.