Bulldozing hydraulic system with bulldozing blade floating function and excavator

A bulldozing hydraulic system with a bulldozing blade floating function, comprising a load-sensitive pump, a bulldozing blade oil cylinder, a load-sensitive valve and a station switching mechanism, wherein:

• the load-sensitive valve comprises a four-position reversing valve;
• the four-position reversing valve at least has a first station, a second station and a third station which are switchable;
• when the four-position reversing valve is at the first station, a port P of the load-sensitive pump is communicated with a small-cavity A port of the bulldozing blade oil cylinder, a large-cavity B port of the bulldozing blade oil cylinder is communicated with an oil tank, oil enters the small-cavity A port of the bulldozing blade oil cylinder and returns from the large-cavity B port, and a bulldozing blade is controlled to ascend;
• when the four-position reversing valve is at the second station, the port P of the load-sensitive pump is communicated with the large-cavity B port of the bulldozing blade oil cylinder, the small-cavity A port of the bulldozing blade oil cylinder is communicated with the oil tank, oil enters the large-cavity B port of the bulldozing blade oil cylinder and returns from the small-cavity A port, and the bulldozing blade is controlled to descend;
• when the four-position reversing valve is at the third station, the small-cavity A port and the large-cavity B port of the bulldozing blade oil cylinder are communicated with a port T of the load-sensitive valve, and the small-cavity A port and the large-cavity B port of the bulldozing blade oil cylinder are communicated with the oil tank, such that the bulldozing blade floating function is realized;
• the station switching mechanism is configured to select and switch the stations of the four-position reversing valve according to a load pressure feedback or a handle signal output.