Compaction device for concrete block molding machine

Claim 1

In a concrete block molding machine of the type comprising: a stationary mold formed with a plurality of vertical cells, each of said cells having an open top and an open bottom; closure means located beneath the mold to close the bottoms of the cells of said mold; means for moving said closure means vertically towards and away from the mold; means for filling the cells of the mold with a non-slump concrete mix when the closure means has been moved toward the mold and is closing the bottoms of the cells of said mold; compaction means for applying a compaction pressure onto the mix poured in the cells, said compaction means comprising: head plate located above the mold; a plurality of compaction shoes connected to said head plate, said compaction shoes being equal in number to the number of cells in the mold and each sized, configured and positioned above the mold for snug insertion into one of the cells of said mold, and means for moving said head plate and compaction shoes bodily towards the mold to apply a predetermined compaction pressure over the mix in the cells; and vibrating means for vibrating the mold while a compaction pressure is applied onto the mix in the cells; the improvement wherein said molding machine further comprises: a plurality of fluid power jacks equal in number to the number of compaction shoes, each of said power jack supporting one of said shoes and comprising a cylinder and a piston rod telescopically mounted within the cylinder for linear, non-rotatable displacement therein, said displacement being such that each power jack has a working stroke essentially equal to a predetermined allowable difference in height of the concrete block to be molded in the corresponding cell; and means for interconnecting the power jacks so that the cylinders of all of said power jacks are in fluid communication with each other; whereby an equal compaction pressure is applied by each compaction shoe in each cell when the compaction means are operated, thereby allowing production of concrete blocks having the same maximum density in all of said cells.