Abstract: Oil filter pliers contains: a fixed part, a movable part, a hollow grip handle, and a press handle. The grip handle is connected with the fixed part which includes a first clamping arm and a hollow connection section, and the moveable part includes an slidable extension and a second clamping arm corresponding to the first clamping arm, wherein the second clamping arm moves close to or away from the first clamping arm by sliding the slidable extension relative to the grip handle. The movable part further includes a first toothed section, the press handle is rotatably coupled with the hollow connection section and includes a driving block and a second toothed section partially engaging with the first toothed section, and between the press handle and the grip handle is defined a torsion spring abutting against the press handle and the grip handle.

Abstract: In the hydraulic breaker according to the present invention, oil pressure at a fixed value always flows in the circuit at a low pressure side whenever the piston is raised or lowered, to prevent the need for an accumulator in the circuit at the low pressure side. At the same time, a high pressure oil is required during the raising and lowering of the piston, bringing about less of a change in the surge pressure, attributing to the fact that there is no need for an accumulator in the circuit at the high pressure side. Moreover, the hydraulic breaker of the present invention is advantageous by providing an increased striking force because the high pressure oil is used, in addition to the reaction force of the compressed nitrogen gas, when the piston is lowered to strike the chisel.

Abstract: In the hydraulic breaker according to the present invention, oil pressure at a fixed value always flows in the circuit at a low pressure side whenever the piston is raised or lowered, to prevent the need for an accumulator in the circuit at the low pressure side. At the same time, a high pressure oil is required during the raising and lowering of the piston, bringing about less of a change in the surge pressure, attributing to the fact that there is no need for an accumulator in the circuit at the high pressure side. Moreover, the hydraulic breaker of the present invention is advantageous by providing an increased striking force because the high pressure oil is used, in addition to the reaction force of the compressed nitrogen gas, when the piston is lowered to strike the chisel.