Automatic air coupling for a rail vehicle, in particular in the form of a goods wagon, having a mouthpiece for coupling the air coupling to an opposite air coupling; having a compressed-air connector for connecting the air coupling to a rail vehicle compressed-air system; having a flow channel which connects the mouthpiece to the compressed-air connector so as to conduct compressed air; having a valve which is arranged in the flow channel and which has a valve body (4.1) and a valve seat (4.2), wherein the valve body (4.1) is movable between an open position, in which it at least largely or completely exposes the flow channel, and a closed position, in which it shuts off the flow channel in a pressure-tight manner; characterized in that a free flow cross section for the compressed air through the mouthpiece, the flow channel, the valve in the open position of the valve body (4.1) and the compressed air connector has a minimum width of 20 mm, and a valve drive is provided which acts at least indirectly on the valve body (4.1) in order to actuate the latter from the open position into the closed position and/or from the closed position into the opening position; wherein the valve drive comprises a shaft (5.1) which is rotatable about an axis of rotation, which is designed for non-rotatable connection to a rail vehicle coupling lock or is formed by a rail vehicle coupling lock and is provided with at least one cam (5.2), which acts at least indirectly on the valve body (4.1) to actuate the latter, and in that the mouthpiece is aligned radially with respect to the axis of rotation relative to its through-flow direction, and the compressed air connector is aligned radially with respect to the axis of rotation relative to its through-flow direction. having a mouthpiece for coupling the air coupling to an opposite air coupling; having a compressed-air connector for connecting the air coupling to a rail vehicle compressed-air system; having a flow channel which connects the mouthpiece to the compressed-air connector so as to conduct compressed air; having a valve which is arranged in the flow channel and which has a valve body (4.1) and a valve seat (4.2), wherein the valve body (4.1) is movable between an open position, in which it at least largely or completely exposes the flow channel, and a closed position, in which it shuts off the flow channel in a pressure-tight manner; characterized in that a free flow cross section for the compressed air through the mouthpiece, the flow channel, the valve in the open position of the valve body (4.1) and the compressed air connector has a minimum width of 20 mm, and a valve drive is provided which acts at least indirectly on the valve body (4.1) in order to actuate the latter from the open position into the closed position and/or from the closed position into the opening position; wherein the valve drive comprises a shaft (5.1) which is rotatable about an axis of rotation, which is designed for non-rotatable connection to a rail vehicle coupling lock or is formed by a rail vehicle coupling lock and is provided with at least one cam (5.2), which acts at least indirectly on the valve body (4.1) to actuate the latter, and in that the mouthpiece is aligned radially with respect to the axis of rotation relative to its through-flow direction, and the compressed air connector is aligned radially with respect to the axis of rotation relative to its through-flow direction.