IC hydraulic screw-bolt spanner

An internal combustion hydraulic bolt spanner driven by an internal combustion engine comprises an oil pump, a selector valve, a overflow valve, a lead relief valve and an actuator. The oil pump being connected with the internal combustion output shaft is a two-way flow oil pump, consisting of an oil pump with large flow and small pressure and an oil pump of small flow and high pressure. The actuator being connected with a reduction box by a hydraulic motor is connected with an operaional sleeve. The selector valve belongs to a two-position three -way valve, being connected with a joint output oil way of the two-way flow oil pump, an oil return way and two oil openings of hydraulic motor respectively. The lead relief valve is located between the output oil way of the oil pump with large flow and small pressure and the oil return way. The hydraulic bolt spanner can meet requirements of differenct torsinal moments with small power, it is concisely configured and controlled with light weight, convenient for move, and applicable for country portable operation.