The mixing drum of concrete mixer truck is shown in the figure, which is generally composed of three sections: front cone, middle cylinder and rear cone. There are two spiral blades symmetrically welded on the cylinder wall with an interval of 180 ° in the cylinder. These two spiral lines form spiral channels with the cylinder wall, and the concrete will complete feeding, mixing and unloading along these spiral channels. Generally, the front cone and rear cone adopt conical logarithmic spiral blades with the same equal lift angle respectively, the middle cylinder is generally a cylinder, and cylindrical spiral blades with different equal lift angles are generally used.

搅拌运输车的搅拌筒是依靠回转的筒体带动两条螺旋叶片对混凝土进行搅拌和卸料作业的。工作时，搅拌筒绕其轴线转动，使得混凝土沿搅拌叶片的螺旋线运动，螺旋曲线促使混凝土沿相反的方向移到末端和，这是混凝土搅拌时的主要运动。同时，由于混凝土与筒壁和叶片的摩擦力及其内在的附着力作用，所以在筒体转动过程中，混凝土达到一定高度后，必在其自重作用下，克服上述摩擦力和内聚力而向下翻跌和滑移。

The mixing drum of the mixer truck relies on the rotating cylinder to drive two spiral blades to mix and unload the concrete. During operation, the mixing drum rotates around its axis to make the concrete move along the spiral line of the mixing blade. The spiral curve urges the concrete to move to the end and top layer in the opposite direction, which is the main movement during concrete mixing. At the same time, due to the friction and internal adhesion between the concrete and the cylinder wall and blades, when the concrete reaches a certain height during the rotation of the cylinder, it must overcome the above friction and cohesion under the action of its own weight and overturn and slip downward.

其次在叶片的底部，由于叶片的形状是曲线型，故混凝土在外力的作用下产生旋转式的搅动。由于搅拌筒在连续的转动，所以混凝土所做的是3种运动混合一起的复合运动，即三维搅拌运动。从而使混凝土被均匀的搅拌，保证其匀质性。

Secondly, at the bottom of the blade, because the shape of the blade is curved, the concrete produces rotary stirring under the action of external force. Due to the continuous rotation of the mixing drum, what the concrete does is a composite motion of three kinds of motion, that is, three-dimensional mixing motion. So that the concrete can be evenly mixed to ensure its uniformity.