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A piston and cylinder arrangement for opening and closing entrance or exit doors or both in a milking compartment of a fully automated milking system. The piston and cylinder arrangement comprises an elongated cylinder having two pistons connected in tandem to an elongated piston rod. The cylinder i

A piston and cylinder arrangement for opening and closing entrance or exit doors or both in a milking compartment of a fully automated milking system. The piston and cylinder arrangement comprises an elongated cylinder having two pistons connected in tandem to an elongated piston rod. The cylinder is hermetically divided into two cylindrical portions each containing one of the pistons. The piston acts against a liquid in one portion and in the other portion the piston is actuated by pneumatic pressure. The piston rod is extended through the end of the cylinder and is connected to open and close an entrance door. The cylindrical portion containing the liquid has the liquid on both sides of the piston connected by a check-valve and a by-pass valve. To block movement of the pistons, the by-pass valve is retained in a closed position by pneumatic pressure from a supply of pressurized gas for actuating the piston in the pneumatic side of the cylinder. The by-pass valve is a sliding valve urged into an open position by a compression spring when the valve is not closed by pneumatic pressure. Both the by-pass valve and the check valve are disposed external to the cylindrical housing.

대표청구항 ▼

1. An operating piston and cylinder arrangement which comprises a housing, a first piston including a piston rod, said first piston being movable in and engaging a wall of said housing, said first piston dividing said housing into a first chamber and a second chamber, said first chamber and said sec

1. An operating piston and cylinder arrangement which comprises a housing, a first piston including a piston rod, said first piston being movable in and engaging a wall of said housing, said first piston dividing said housing into a first chamber and a second chamber, said first chamber and said second chamber having a first operating entrance and a second operating entrance, a fluid supply from which fluid can be selectively supplied to said first chamber and said second chamber and can be discharged therefrom into said first operating entrance and into said second operating chamber, a blocking device for blocking said piston rod in one direction, said blocking device comprising activating means which comprise a third operating entrance which can be selectively connected to said first operating entrance or said second operating entrance or both by said activating means.