PURPOSE:To detect the grounding pressure accurately by forming the part for transmitting the grounding pressure to the sensor in a lever form so that the grounding pressure from the float is amplified and transmitted to the grounding pressure sensor. CONSTITUTION:The force the float 63 receives from the surface of the water paddy is transmitted through connection pin 77 at the action point to the lever 73 and the lever 73 swings upward around the shaft 74 resisting the repulsion of the spring 79. Thus, the detection rod 81a is pushed up by the connection pin 80 and the contraction of the spring 79 corresponding to the grounding pressure is shown as a stroke of the grounding pressure sensor 81. The distance L from the swing point to the force point is much larger than that from the swing point to the action point, and even slight change of the float 63 is amplified at the grounding pin 80 and exact pressure can be detected.
