A discharge cut-off valve for an air compressor is provided. The discharge cut-off valve includes a hinged leaf valve within the recessed portion of a cylinder head manifold. The hinged leaf valve is rotatably anchored at a first end to a joint pin and is guided at a second end by a guide pin. In the on-load phase, the hinged leaf valve is seated over an unloader vent opening while a discharge vent opening is uncovered. In the off-load phase, the hinged leaf valve is seated over the discharge vent opening while the unloader vent opening is uncovered. As a result, compressed air is prevented from escaping the discharge port of the air compressor during the off-load phase, obviating the need for a down-stream turbo cut-off valve in an air dryer, for example.

A discharge cut-off valve for an air compressor is provided. The discharge cut-off valve includes a hinged leaf valve within the recessed portion of a cylinder head manifold. The hinged leaf valve is rotatably anchored at a first end to a joint pin and is guided at a second end by a guide pin. In the on-load phase, the hinged leaf valve is seated over an unloader vent opening while a discharge vent opening is uncovered. In the off-load phase, the hinged leaf valve is seated over the discharge vent opening while the unloader vent opening is uncovered. As a result, compressed air is prevented from escaping the discharge port of the air compressor during the off-load phase, obviating the need for a down-stream turbo cut-off valve in an air dryer, for example.

An unloading device is applied to an air compressor including a plurality of cylinders, and includes: a plurality of unloading valves, each unloading valve movably covering an unloading hole of one cylinder; an unloading cavity in communication with the unloading hole; an intake cavity in communication with the unloading cavity; and a piston member connected to the plurality of unloading valves by means of a shift fork. In an unloading state, the piston member is capable of driving, by means of the shift fork, the unloading valve to move to uncover the unloading hole, so that air in the plurality of cylinders circulates back and forth through the unloading cavity to make the air compressor enter the unloading state, and the air compressor maintains an optimal unloading state by using the intake cavity in communication with the unloading cavity.