The mixing drum structure shall be simple, compact and lightweight to minimize the self weight of the truck, which is conducive to improving the effective loading capacity of the mixing truck and relatively reducing the power consumption of the truck. At the same time, the layout of the structure shall adapt to the narrow and long shape and height limit of the chassis. The height and center of gravity of the mixing drum and the mixing truck shall be reduced as far as possible to ensure the driving stability and trafficability of the mixing truck. In addition, it shall have sufficient effective loading capacity to meet the specified mixing, loading and unloading performance, and adapt to the characteristics of the carrying chassis and mixing work. The shape of the mixing drum is relatively complex, and the section diameter along the axis direction changes. The diameter of the middle part is large, and the two sides gradually shrink. For the mixing drum with large capacity, a cylinder is added between the two truncated cones to expand the loading volume and avoid excessive size in the middle of the mixing drum.

一般情况下，搅拌筒的前锥、中锥、后锥长度的参数选取如下：

Generally, the parameters of the length of the front cone, middle cone and rear cone of the mixing drum are selected as follows:

通常情况下大直径取在2100~2300mm之间，如果大直径取在2400mm,搅拌运输车在转弯时就会有发飘现象，就有可能造成事故。

Generally, the large diameter is taken as 2100 ~ 2300mm. If the large diameter is taken as 2400mm, the mixer truck will float when turning, which may cause accidents.

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顶层，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。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。

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. 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.