fig1 - 3 show an embodiment of the present invention , generally indicated by the reference numeral 10 . the assembly 10 is shown fully assembled in fig1 and with the top plate member 200 removed in fig2 . fig3 provides an exploded view of the assembly 10 of fig1 in which a generally rectangular mold frame 15 is composed of a side bar member 20 , an opposed stop bar member 25 and a pair of spaced apart , outside division plate members 30 , each having a top edge 35 . the components of the mold frame 15 are each generally rectangular and secured together with each end of the side bar member 20 and stop bar member 25 extending beyond the plane of attachment of each of the two division plate members 30 . the side bar member 20 and stop bar member 25 each has a pair of vertical retaining slots 40 , each slot 40 with a slot aperture 45 therein . the division plate members 30 include a retaining peg 50 at each end . each plate member end fits into one of the retaining slots 40 with the retaining peg 50 inserted into the slot aperture 45 . the bar members 20 , 25 and plate members 30 are further secured together by retainer straps 55 , secured between the bar members 20 , 25 beneath each plate member 30 . the mold frame 15 is sized to accept a plurality of wear liners 60 that define the concrete block produced by the core puller / mold assembly 10 . the wear liners 60 are fabricated from steel alloy for strength and resistance to abrasion by the concrete fill used to produce each block . the wear liners 60 have planar top 65 and bottom 70 surfaces and fit together within the mold frame 15 , such that the liner interior surfaces 75 define a mold cavity 80 that produces the concrete block . the mold cavity 80 is open at both the top and bottom , with vertical interior surfaces 75 . the interior surface of the bar members 20 , 25 and plate members 30 each contain a horizontal channel 85 . the wear liners 60 are provided with alignment ridges 90 on their exterior surfaces 95 , which fit into the horizontal channels 85 of the bar members 20 , 25 and plate members 30 . additionally , the alignment ridges 90 are provided with a number of threaded blind holes 100 that align with apertures 105 in the channels 85 for securing the various wear liners 60 to the bar member 20 , 25 and plate members 30 with threaded fasteners ( not shown ). thus , the mold frame 15 and associated wear liners 60 provide a structurally rigid mold portion that is easily disassembled for changing wear liners 60 to produce various shaped concrete blocks . an actuation cylinder 150 is secured horizontally to an exterior side of each division plate member 30 . each actuation cylinder 150 is secured thereto , by a pair of cylinder mounts 155 and associated mount spacers 160 . the actuation cylinders 150 are sized to fit between the ends of the bar members 20 , 25 that extend beyond each division plate member 30 . each actuation cylinder 150 has a moveable rod member 165 , extending from one end thereof , through a rod aperture 170 in the side bar member 20 . the cylinder rod members 165 are fastened to a core mounting bracket member 175 via rod connectors 180 at each end of the bracket member 175 . at least one core bar member 185 is fastened at one end to the bracket member 175 . in this embodiment , two core bar members 185 are fastened to the bracket member 175 , with the core bar member 185 extending through a core slot 190 in the side bar member 20 . the bracket member 175 and core slot 190 are positioned so as to direct the core bar member 185 along one surface of the block mold . in this embodiment , each core bar member 185 traverses the mold cavity 80 at opposite ends thereof , adjacent the top plate member 200 . the cylinder rod members 165 and core bar members 185 are sized so that , with the cylinder rod members 165 extended from the cylinders 150 , the core bar members 185 are completely removed from the mold cavity 80 , and with the cylinder rod members 165 retracted into the cylinders 150 , the core bar members 185 extend completely across the mold cavity 80 . the core bar members 185 are , preferably , reversibly fastened to the bracket member 175 should replacement of the core bar members 185 be required . to further reinforce the core puller / mold assembly 10 , a top plate member 200 is secured atop the mold frame 15 . the top plate member 200 is planar with a core aperture 205 sized to be larger than the open top of the mold interior cavity 80 . the top plate core aperture 205 is sized to allow the division plate members top edges 35 to extend there through , along opposed edges thereof . the top plate member 200 also includes apertures 210 for fastening the plate member 200 to the side bar and stop bar members 20 , 25 for added structural stability . the top plate member 200 also includes upwardly extending edges 215 on three sides and a downwardly extending fourth edge 220 for low level access to the open top of the mold cavity 80 . a block machines of the type with which the core puller / mold assembly 10 is used is shown schematically in fig4 . the block machine 400 is supplied with pallets 405 by a conveyor 415 . the pallets 405 are raised into position , as by a lower lift unit 410 . the molds are filled by a metering chute ( not shown ) and an upper stripper head unit 420 , having a movable height pin 430 connected thereto , which is lowered into position until the height pin 430 engages a relatively fixed height pin 440 . the height pins 430 and 440 determine the height of the blocks and also provide electrical contacts , which close to initiate termination of the vibration cycle and also actuate the stripping action of the head unit 420 by way of the delay timer 445 . the delay timer 445 also sends a signal to the core puller / mold assembly 10 , so that the core bars 185 are retracted prior to the stripping action . the safety switch actuator 425 mounted to the core bar mounting bracket 175 of the assembly 10 is incorporated into the block machine circuitry to preclude stripping of the mold cavity 80 until the safety switch 425 is closed . the sequence of operation begins with the core bars 185 fully extended into the mold cavity 80 . when the core bars 185 are in place in the mold assembly 10 , a pallet member 405 is moved into position below the cavity 80 . following this , the mold cavity 80 fills with concrete , and vibration of the block machine commences . engagement of the height pins 430 and 440 initiates termination of vibration . prior to the complete termination of vibration , the block machine delay timer 445 , actuated by engagement of the height pins 430 , 440 , sends a signal to the drive unit timer 435 , which actuates the air supply to the cylinders 150 . the core bars 185 are retracted , when drive unit timer 435 times out , by supplying air to the cylinder front air inlets at the same time as the vibration is completed , since stripping action begins very shortly , about four - tenths ({ fraction ( 4 / 10 )}) of a second , after completion of vibration . the completed blocks are lowered with the pallet member 405 and transported by the conveyor 415 to storage or curing . when the drive unit timer 435 again times out , air is supplied to the cylinder rear air inlets , and the core bars 185 re - enter the mold assembly liner cavity 80 shortly before another pallet member 405 is raised into position for the next cycle . the plunger assembly 300 used to remove the formed block from the core aperture 80 of the core puller / mold assembly 10 is shown in fig5 . the plunger assembly 300 is positioned above the block - filled core aperture 80 with the stripper shoe 310 contacting the block upper surface . the downwardly extending edge 220 of the top plate member 200 provides clear , low - level access for the plunger assembly 300 to the top of the mold assembly 10 . the stripper shoe 310 is configured to match the core aperture 80 , such that downward movement of the plunger assembly 300 strips the block cleanly from the mold cavity 80 . the stripper shoe 310 is secured to a plunger weldment 320 which , in turn , is fastened to a head plate 330 . the plunger weldment 320 footprint is smaller than the stripper shoe 310 , so as to pass into the mold cavity 80 without contacting the vertical surfaces 75 of the mold . the head plate 330 provides for attachment of the plunger assembly 300 to the stripper head unit 420 of the block machine 400 . the descriptions above and the accompanying drawings should be interpreted in the illustrative and not the limited sense . while the invention has been disclosed in connection with an embodiment or embodiments thereof , it should be understood that there may be other embodiments which fall within the scope of the invention as defined by the claims . where a claim , if any , is expressed as a means or step for performing a specified function , it is intended that such claim be construed to cover the corresponding structure , material , or acts described in the specification and equivalents thereof , including both structural equivalents and equivalent structures , material - based equivalents and equivalent materials , and act - based equivalents and equivalent acts .