Abstract: A control apparatus for an apparatus that cleans the drum of a ready mixed concrete truck includes a CAN-bus control system that includes a nozzle lance position encoder, a boom position encoder, a human-machine interface, a programmable logic controller, and monitors for an engine, hydraulic valves, and pressure sensors. The nozzle lance position encoder includes a rotary encoder, a bi-directional motor, a nozzle lance including a nozzle adapted to discharge water under high pressure, and a swivel assembly to which the nozzle lance is mounted for reciprocating motion. The programmable logic controller enables an operator to control the range of oscillation of the nozzle lance by inputting a desired range of oscillation into the programmable logic controller. An operator can also control extension and retraction of an elongate boom by inputting a desired rate of extension and retraction into the programmable logic controller.

Abstract: Residual concrete in the drum of a ready mixed concrete truck is removed by high-pressure water. A nozzle is mounted on the leading end of a torpedo-shaped nozzle housing that is hingedly mounted to an elongate boom. The boom enters the mouth of the drum at an angle that matches the angle of the drum. The hinge allows the nozzle housing to pivot with respect to the elongate boom so that the nozzle is close to the residual concrete. The boom is retracted toward the mouth with the drum rotating in the mix direction and the nozzle oscillating so that it cuts through a swath of concrete. As the boom retracts, the torpedo-shaped nozzle housing maintains the nozzle close to the residual concrete on the drum and both sides of the helical fins. The nozzle sweeps an arc from about eighty to one hundred twenty degrees as it oscillates.