This balance valve is installed on the hydraulic cylinder return oil line of the crane winch mechanism. It can effectively solve the problem of excessive speed slippage caused by gravity when the winch lowers heavy objects. When the hydraulic system pressure is out of control and there is a risk of the load falling off the machine, it will automatically limit the return speed of the hydraulic oil, prevent the load from falling rapidly, and avoid serious accidents that could damage equipment or endanger the safety of personnel on site. It is an important safety protection component of the winch mechanism.