A power take-off unit is connected to a power take-off gearport on a concrete mixing truck transmission, the power take-off unit being driven by the engine so it is always providing power as long as the engine is running. The control unit switches an operation mode between a lock step mode for the first and second processors to execute the same instruction stream and a free step mode for the first and second processors to execute different instruction streams. An absorbent system is disposed between the topsheet and the backsheet. A serving interval is determined for each flow based on the requirements for the flow. The gear clutch and the hammer crosspiece clutch are movably fitted with the teeth shaft of the middle shaft.