• Body - Main valve - Spring - automatic shut-off lever - Switch film - Vice valve pedestal - switchovar cover - Nozzle mouth - Air inlet - Air-antry pipe - Vice valve core - self-controlling pole - top lever - Block flake - Direction-limited plate - Switch handle

When the machine starts, the main valve is open, the pressured oil flows into the cavity between the main valve and vice, driving the vice valve open and vents out from nozzle mouth. During the course, the flow of oil reduces with action less pressure, which reduces the pressure of the upper cavity of switch film, but air inlet at the front end of nozzle mouth aerates which equals to the pressure of two cavities (low pressure and high pressure cavity) of the switch film and balances it. When the oil submerges the air inlet, the upper cavity is isolated without air forming negative pressure, but the lower cavity remains normal pressure, so pressure gap appears between two cavities making switch film lose balance, and the automatic pole moves up with the film. At the same time, self-controlling pole is moving down under the pull of handle, which extrusts the stell ball into the hole of it. thus, as losing supportable point, the handle moves down and closes main valve, fueling stops automatically.