A fluid operated breaker is provided which is operable particularly for purposes of imparting repetitive blows to a tool operatively connected thereto whereby to drive the tool into engagement with a surface such as concrete, asphalt, rock, etc. so as to effectuate a fast easy breaking of the surface. The breaker includes a housing in which there is provided an ON-OFF lever valve, a piston, a reversing spool, an accumulator, and circuit means operable for fluidically interconnecting these components. The lever valve, piston and reversing spool are each supported in the housing of the breaker so as to be movable therein between first and second positions. The circuit means functions to establish fluid flow passages between the lever valve, piston and reversing spool through which fluid is caused to flow to alternately drive the piston in a power stroke and a return stroke. The piston has a stepped design wherein the piston force area is independent of the piston diameter which allows for the use of small force areas and reasonable piston mass to reduce the fluid flow requirements and maintain high levels of energy output. The reversing spool is also provided with a stepped construction which allows for large valve size for free fluid flow, yet retains small switch areas and light weight due to hollow construction. In addition, the breaker is provided within the circuit means thereof with a variable restriction in the circuit to the outlet which can be used to vary the pressure on the return stroke and thus the energy output through variation of the pressure applied to the accumulator.