Safety pressure relief device of cable logging tractor

The utility model relates to the field of petroleum engineering equipment manufacturing, and discloses a safe pressure relief device of a cable logging tractor, which comprises a shell and a lower shell, the upper section of a connecting piece is sleeved in the shell, the lower section of the connecting piece is sleeved in the lower shell, the lower end of the connecting piece is connected with a pushing motor, the output end of the pushing motor is connected with a plunger pump, and the plunger pump is connected with a hydraulic cylinder. An oil outlet head at the front end of the plunger pump is inserted into a high-pressure oil channel of the control valve set, a low-pressure oil channel is formed in the periphery of the plunger pump and the periphery of the control valve set, the middle section of the connecting piece is located between the outer shell and the lower shell and provided with an annular clamping groove, a threaded ring is clamped in the clamping groove, the upper section of the threaded ring