Abstract: A concrete mixer is disclosed having a mixing drum and a drag body is mounted in the drum which has a drag surface positioned to at least partially come into contact with concrete in the drum during a measuring phase in the concrete mixing operation. A hydraulic driving circuit is provided to oscillate the drag body at least during the measuring phase. A pressure sensor is connected in the hydraulic driving circuit for measuring the actual pressure value in the hydraulic driving circuit which is indicative of the flow resistance on the drag surface during the measuring phase of the mixing operation.

Abstract: The invention relates to a concrete mixer truck having a mixer drum adapted to be rotated by the traction motor of the vehicle through an auxiliary transmission of the traction motor transmission. It is an object of the invention to ensure that the power supplied by the traction motor is effectively available for traction purposes under conditions of increased power demand, such as starting and accelerating, and/or that the torque of the mixer drum does not interfere with gear shift operations. To this effect the invention provides a control means adapted to disconnect the mixer drum rotating transmission from the traction motor transmission during predetermined travel conditions, i.e. under conditions defined by an increased power demand for locomotion of the vehicle. Also included in these conditions is each gear shift operation, as at this instance the torque of the mixer drum is prevented from influencing the rotary speed of the speed shift transmission.

Abstract: The invention relates to a concrete mixer truck having a mixer drum adapted to be rotatably driven, a water container, a water conduit leading from the container to the drum, and a water pump. An object of the invention is to prevent the quality of a properly composed mixture contained in the drum from being deteriorated by unintentional addition thereto of water from the water container. This is accomplished by the use of a measuring device determining the drive torque for the mixer drum and a valve disposed in the water conduit and controlled by said measuring device in such a manner that the water conduit is closed when the drive torque exceeds a selectively adjustable rated value corresponding at least to the drive torque required for the empty drum.

Abstract: The invention relates to a concrete mixer, particularly to a truck-mounted concrete mixer, comprising a drum and an actuatable additional mixer tool projecting into the drum from the bottom thereof substantially in the direction of the drum axis. A rotatably driven mixer tool of this type requires the employ of additional gearing, and a sealing assembly for the passage of its shaft through the drum bottom is very complicated and subjected to wear. In accordance with the invention, these disadvantages are avoided by the provision that the mixer tool is adapted to be moved in the axial direction. This permits a cylinder-piston unit to be employed as the drive source for the mixer tool. No gearing is required, and sealing as well as maintenance are simplified.

Abstract: The invention relates to a concrete mixer, in particular a free-fall mixer, in which the components of the concrete, in particular initially without water, can be intermixed by mixing elements by means of the rotation of a drum, wherein a vibrator is provided.The object of the invention is to make the mixing process easier and to save energy. This object is attained in that a vibrator which is switched on during the mixing process in order to reinforce it is disposed in the drum in the vicinity of the material to be mixed.

Abstract: A concrete mixer having a drum, which contains mixing elements, and at least one vibrator for imparting vibrational energy to the material which is to be mixed. The vibrator is drivable by means of the water used to make up the concrete. The water may be discharged in a pulsating manner from a vibrating body which is caused to vibrate by this pulsation, or it may rotatably drive an eccentric mass in the vibrating body.

Abstract: This invention relates to apparatus for making ready-mixed concrete, comprising a plurality of transfer containers divided into separate chambers and adapted to be moved along a closed path to at least one filling station and a plurality of emptying or waiting stations, respectively, for temporarily containing cement, filling materials and possibly, water separately from one another and for transferring these materials to concrete mixer trucks, particularly to mixer trucks provided with positive mixing tools.