According to the actual situation of v-belt drive

the radial deformation and circular deformation of any position of dynamic arc area of driving wheel and driven wheel are analyzed

and the calculation formula of friction direction angle is given

the relational graph of dynamic arc angle and direction angle are obtained by using Matlab.Through the analysis of the influence of friction direction angle on equivalent friction coefficient

the regular of the equivalent friction coefficient of that the equivalent friction coefficient of driven wheel decrease with the increase of direction angle

the equivalent friction coefficient of driving wheel increase with the increase of absolute of direction angle.According to the equivalent friction coefficient of the driving wheel μv≥μ/sin（θ/2）

and combining the formula of limit skid torque

the number of actual limit skid torque larger than the number of theory limit skid torque can be explained.