The formulas concern two kind of saw chains with same pitch and different pitch and three kind of sprockets, which are rim sprocket, spur sprocket and nose sprocket.

In this paper, fourth moment of end-to-end distance of polymethylene chains in the third-order interaction approximation is calculated.

In this paper, the simulate curve and result for the backlash Center Adjustable Gear train in various cases are given by the random simulate method.