If the object is in pure roll, the friction could be substantially less than the maximum friction possible.
如果是纯滚动，摩擦基本上，小于可能的，最大值。
2
The numerical solution of the equation describing the motion of the floating piston pin is obtained by bringing in the conception of friction force coefficient under slide-roll condition.
引入滚滑状况下的摩擦力系数，从而求得活塞销运动方程的数值解。
3
If the roll core is made of special materials, smaller friction coefficient of tile can be used.