Abstract: A milking machine tap assembly for connecting a teat cup unit with a vacuum pipe and a milk pipe extending within the vacuum pipe. A tap box unit is provided which has a housing with a window opening in its side wall, and two axially aligned connecting tubes at opposite ends of the housing to connect with confronting sections of the vacuum pipe. A tubular milk tap body within the housing has its ends arranged to connect with confronting sections of the milk pipe, the tap body also having a first port through its side wall to enable the teat cup unit to communicate with the milk pipe through the tap body. A tap frame is fixed to the housing over the window opening to position the first port. An air packing is mounted on the frame and cooperates therewith to form a second port which enables the teat cup unit to communicate with the vacuum pipe through the housing interior. A gate is slidably mounted to the frame for simultaneously closing the first and second ports.