Patent ID: 7611331

Claim:
A thick matter pump with two conveyor cylinders ( 50 , 50 ′) communicating via two end openings ( 52 ) in a material supply container ( 54 ), the two conveyor cylinders ( 50 , 50 ′) operated in counter stroke by a hydraulic reversible pump ( 6 ) via hydraulic drive cylinders ( 5 , 5 ′) driven by said pump, with a hydraulically actuated pipe switch ( 56 ) provided within the material supply container ( 54 ), the pipe switch having an inlet and an outlet, the pipe switch inlet being alternatingly connectable to one of the openings ( 52 ) of the conveyor cylinders ( 50 , 50 ′), freeing the respective other opening of the conveyor cylinders ( 50 , 50 ′), and the pipe switch outlet being connected with a conveyor conduit ( 58 ), wherein the drive cylinders ( 5 , 5 ′) are each hydraulically connected at one end with an opening of the reversible pump ( 6 ) via respectively one hydraulic line ( 11 , 11 ′), and wherein the drive cylinders ( 5 , 5 ′) on their other end are connected to each other via an oscillating oil line ( 12 ), and further comprising a reversing device ( 18 ) for reversing the reversible pump ( 6 ) after the conclusion of each piston stroke, wherein the reversing device includes a computer assisted routine ( 84 , 82 ) for determining an expected stroke duration and for the recording thereof in a data storage as well as for monitoring the time during each piston stroke, and initiating a reversal of at least one of (a) the pipe switch ( 56 ) and (b) the flow through reversal of the reversible pump ( 6 ) based on a comparison of the value of an elapsed stroke time with the expected stroke duration.