混砂机为柱塞式油泵用来供给齿轮和轴承充足的润滑油，装在减速箱内斜齿轮轴的下部借该轴的旋转，带动油泵推杆座压缩活塞使共做周期性往复活动，活塞下降时，进油口关闭出油口打开，润滑油进入油管。活塞上升时，进油口动作与前相反，如此循环不断的动作使油不断打入油管喷出。

Sand mixer forplunger pump used to supply sufficient gear and bearing lubricating oil, in aslow down in the bottom of the inclined shaft by the axis of rotation, drivenpush rod seat compression piston pump lets do periodic reciprocatingactivities, piston falls, inlet open close the oil outlet, lubricating oil intothe tubing. The piston rises, inlet action, in contrast to the former, soaction keeps the oil continue to spew into the tubing.