The invention provides a hydraulic
system of a crane. The hydraulic
system of the crane comprises a crane body, wherein a main arm is fixed at the upper part of the crane body; a hydraulic
oil tank isfixed on the side of the crane body; a motor and a one-way
throttle valve are mounted at the top of the hydraulic
oil tank; a
gear pump is arranged inside the hydraulic
oil tank; an S-shaped coolingpipe is arranged under the
gear pump; the
gear pump is connected with the motor through a coupler; the gear pump is connected with the one-way
throttle valve through a hydraulic oil
pipe; an
oil storage tank is arranged on the hydraulic oil tank; a filtering net is arranged between the
oil storage tank and the hydraulic oil tank; the
oil storage tank is connected with an oil returning
pipe; a balancing valve is mounted in the oil returning
pipe; a cooling water tank is also fixed on the side of the crane body; a water pump is arranged in the cooling water tank; a
booster pump communicated withthe cooling water tank is arranged on the side of the cooling water tank; a water pump is communicated with a water inlet of the S-shaped
cooling pipe through a pipeline. According to the hydraulic
system of the crane, the S-shaped
cooling pipe is used for cooling the hydraulic oil, so that the problem that the temperature of the hydraulic oil is increased to an excessively high temperature whenthe crane carries out the hoisting operation for a long time is solved.