A solid waste material comminuting system having .[.a.]. .Iadd.an .Iaddend.electric motor for providing rotary motion, a pair of cutter stacks with cutter elements of one stack interleaved with cutter elements of the other, and gear means to transmit the rotary motion of the electric motor to counter-rotate cutter elements of one stack with cutter elements of the other. Each of the cutter stacks comprises a central shaft journaled for rotation and a .Iadd.seal-.Iaddend.bearing .Iadd.assembly/.Iaddend.module at each end of the central shafts. Each .[.bearing.]. .Iadd.assembly/.Iaddend.module comprises an end housing, and a pair of insertable pre-assembled .Iadd.seal-.Iaddend.bearing .Iadd.elements/.Iaddend.assemblies mountable in each of said end housings. One .Iadd.seal-.Iaddend.bearing .Iadd.element/.Iaddend.assembly has a thru-hole for journaling a first shaft for rotation and a second .Iadd.seal-.Iaddend.bearing .Iadd.element/.Iaddend.assembly has a thru-hole for journaling a second shaft for rotation.