A concrete mixer truck is made up of several parts, including: -Chassis: The frame of the truck that supports the weight of the vehicle and all of its components. -Mixing drum: A cylindrical container mounted on the chassis that holds and mixes the concrete. -Hydraulic system: Consists of a motor, pump, and valves that power the drum rotation and tilting. -Engine: The power source that drives the truck's wheels and the hydraulic system. 

These are some of the main parts of a concrete mixer truck, but there are other smaller parts that make the truck function properly.