Patent ID: 7887023

Claim:
A fluid-transfer coupling device comprising: a cylindrical slider slidably inserted into a cylindrical housing, the cylindrical slider containing a valve sleeve accommodating a valve which is adapted so as to open by pressure; a piston formed at a rear end of the cylindrical slider so as to make a slide contact with an inner wall of the cylindrical housing, the piston being constructed so that entry and exit of pneumatic pressure on both sides of the piston allows the slider to be moved in the cylindrical housing; engaging means arranged at a forward end of the cylindrical slider so as to engage with a plug to be connected to the cylindrical slider, the engaging means allowing the plug to be drawn up to an advanced end in the valve sleeve with a movement of the cylindrical slider; and plug supporting means for supporting the plug on condition of being drawn up to the advanced end in the valve sleeve by the movement of the cylindrical slider, wherein the plug supporting means is provided with an improper connection preventing mechanism for preventing other plugs except a specified plug from being connected to the fluid-transfer coupling device, wherein the improper connection preventing mechanism includes at least one key groove formed on an outer circumferential face of the specified plug and a key for engagement with the key groove, wherein the plug supporting means is formed with an opening into which the plug is inserted, and wherein the plug supporting means is fixed in at least three positions around the opening.