Surface-chiseling machine

A surface-chiseling machine for refractory, concrete of other materials, which comprises a piston having at its one end a step portion and on a side periphery at its other end a through-hole, and a cylinder forming a first air chamber on a closed side of the step portion of said piston, forming an exhausting channel communicated with the through-hole of said piston and having an air hole for feeding a pressure air to said first air chamber, said cylinder at its rear end being closed with a back head for forming therein a second air chamber while at its front end being closed with a front head which is provided with a plurality of chisel-inserting holes, into which holes are inserted chisels with their rear ends being contactable directly with a front face of said piston, each of said chisel at its rear end being provided with a protruded step to form on its one side a third air chamber for normally urging the chisel against the piston, said first and third air chambers being continuously fed with the pressure air for reciprocating said piston in a strike in which the second air chamber formed by said piston is communicated alternately with the exhausting channel or the first air chamber via the through-hole, thereby to strike the chisel.