Control means for concrete laying machines

Claim 1

A CONCRETE LAYING MACHINE COMPRISING A MAIN FRAME, WHEELS SUPPORTING SAID MAIN FRAME, A VARIABLE SPEED DRIVE MOTOR ON SAID FRAME COUPLED TO SAID WHEELS FOR DRIVING SAID FRAME, A SUB-FRAME, A CONCRETE FORMER SUPPORTED BY THE SUB-FRAME, A MANDREL EXTENDING INTO SAID FORMER, SPACED PARALLEL ARMS HAVING UPPER AND LOWER ENDS, SAID ARMS DEPENDING FROM SAID BEING PIVOTED AT THEIR UPPER ENDS TO SAID SUB-FRAME, BEARINGS SUPPORTED BY SAID ARMS AT THEIR LOWER ENDS NORMAL TO SAID MANDREL, SAID MANDREL BEING SUPPORTED IN SAID BEARINGS FOR ROTATIONAL MOVEMENT BUT BEING AXIALLY RESTRAINED AGAINSAT RELATIVE AXIAL MOVEMENT IN SAID BEARINGS, SAID MANDREL BEING RETAINED PARALLEL TO SAID CONCRETE FORMER BY SAID SPACED PARALLEL ARMS, A HELICAL BLADE ON THE MANDREL, A MANDREL DRIVE MOTOR COUPLED TO SAID MANDREL AND ARRANGED TO DEIVE SAID MANDREL CONTINUOUSLY; AND CONTROL MEANS COMPRISING: A HYDRAULIC MASTER CYLINDER INCLUDING A PISTON BETWEEN SAID HINGED ARMS AND SAID FRAME, A HYDRAULIC SLAVE CYLINDER INCLUDING A PISTON ON SAID FRAME, AN ENCLOSED HYDRAULIC FLUID CONTAINING PRESSURE TRANSMITTING LINE INTERCONNECTING SAID MASTER AND SLAVE CYLINDERS, A SPRING BETWEEN SAID SLAVE CYLINDER AND THE PISTON THEREIN, A THROTTLE VALVE ON THE MAIN FRAME COUPLED TO SAID DRIVE MOTOR, AND A LINK BETWEEN SAID SLAVE CYLINDER PISTON AND SAID THROTTLE VALVE, SUCH THAT AXIAL MOVEMENT OF SAID MANDREL RELATIVE TO SAID FRAME BOTH COMPRESSES SAID SPRING AND ALSO ACTUATES SAID THROTTLE TO INCREASE THE SPEED OF SAID DRIVE MOTOR THEREBY MAINTAINING SUBSTANTIALLY UNIFORM PRESSURE ON CONCRETE EXTRUDED BY SAID MANDREL THROUGH SAID FORMER IRRESPECTIVE OF THE RATE OF CONCRETE FEED.