In the mechanism showed in following figure, driving link 1 rotates in constant angular velocity  by driving torque . Frictional circles of revolute pairs are labelled in the figure. Frictional angle .  is working resistance. Mass and inertia force of each link are not calculated. Try to label the position and direction of total reaction force of each kinematical pair and write force balance equation for link 2 and draw vector polygon to resolve this equation. 评分规则:  参考课堂讲解