Diaphragm pump and pump for double-breast pumping

A pump mechanism for a breastpump comprising:

• a motor;
• a first and a second expansible chamber, each said expansible chamber having an element which is moveable relative to a base member with said element and base member being generally air sealed with respect to each other so as to form a variable volume between them and produce at least a negative pressure by movement of said element relative to said base member, with an outlet for connecting to a breastshield in communication with a respective variable volume and;
• a drive train being connected to said motor and to said first and second expansible chambers to move each expansive chamber element relative to a respective base member, wherein said element is a flexible diaphragm and said base member is a rigid member to which said diaphragm is mounted and having a respective outlet formed in said rigid member, said diaphragm being movable in relation to said rigid member by the drive train, which includes an eccentric which is rotated by said motor, with a puller mounted to move with said eccentric and connected to a yoke, the diaphragms of said first and second expansible chambers being connected to said yoke, so as to expand and contract the volumes of said expansible chambers in tandem as said eccentric is rotated.