A optimal design mathematics model for crank_rocker mechanism is established on the base of analyzing practical condition of plough unloader.

• 电动组合式犁式卸料器犁头的起落和托辊的升降靠曲柄摇杆机构实现,为使两者的动作协调一致,需要对曲柄摇杆机构的参数进行优化。