PURPOSE: To provide an equipment for forced feeding of liquid where the number of parts is reduced and the structure is simplified, the working liquid introducing port or the like can be opened/closed by the strong snap-moving force, the operation is smooth and few failures are found.

CONSTITUTION: A compression spring 66 is mounted on the tip of a main lever 63 which sways in the interlocking manner with a float 13, and the other end of the compression spring 66 is connected to a slider 65 supported by a guide roller. As the main lever 63 sways, the end part of the compression spring 66 is moved, and the snap movement of the slider 65 is started when the compression spring 66 becomes orthogonal to the slider 65.