On-off control mechanism for single-rope bucket grab

The utility model relates to an open-close control unit for a single cable grab bucket. The utility model includes two oil cylinders, each oil cylinder includes a cylinder body, a piston rod and a piston, the cylinder body is arranged on a lower bearing beam of the grab bucket. The piston rod is connected with a sliding base of the grab bucket. The center of the piston has a hole connected with an upper cavity and lower cavity of the cylinder body. The bottom of the cylinder body has a thimble, the center of the thimble has a run-through hole; the bottom of the cylinder body has a No.1 oil port and a No.2 oil port arranged in parallel. The No.1 oil port is communicated with the run-through hole. The No.2 oil port is communicated with a rodless cavity; each oil cylinder also includes a set of single way valves controlling one-way oil flow from upper cavity to the lower cavity of the cylinder, the single way valves are positioned on the piston or pipes outside the oil cylinder. A rod cavity adjustment control circuit, including a hydraulic pipe and a reversal valve, the hydraulic pipe is connected between the No.1 oil port and an oil tank, the reversal valve is arranged on the hydraulic pipe to control the oil flow direction between the No.1 oil port and the oil tank. A rodless cavity control circuit is connected between the oil cylinder No.2 oil port and the oil tank to adjust the No.2 oil port oil discharge backup pressure and oil suction speed.