Switching piece, oil tank and excavator

The invention discloses a switching piece, an oil tank and an excavator, the switching piece comprises a switching plate and a floating block connected with the switching plate, and the floating block is used for driving the switching plate to ascend or descend through buoyancy so as to change a circulation structure in a containing cavity; the oil tank further comprises a shell, a containing cavity is formed in the shell, a partition piece is arranged in the shell and divides the containing cavity into a left cabin, a right cabin and a channel communicating the left cabin with the right cabin, a switching cabin is formed in the partition piece, and the switching cabin is located at the top of the channel. The switching plate is connected with the partition in a lifting mode and used for stretching into the channel to reduce the cross sectional area of the channel, and then the circulation structure in the containing cavity is changed. By arranging the switching piece in the oil tank, the double functions of