Suction device for piston breast pump

A breast pump with a piston suction arrangement, comprising:

• a casing (3);
• a base (4) provided on said casing and comprises a gear shaft (5) provided thereon;
• a piston unit for providing suction, and comprises:
• a handle (1) mounted to said base and extended outside said casing and arranged for pressing;
• a cylinder member (12);
• a piston member (19);
• a toothed member (17) connected to said piton member;
• and
• a gear unit operatively connected with said toothed member (17) and said handle (1) such that said toothed member and said handle are connected such that a reciprocating movement of said handle in an up and down direction is changed into a reciprocate movement of said piston member at a back and forth direction, wherein said gear unit comprises a first gear (6) mounted on an exterior end of said gear shaft (5), a second gear (7) operatively connected to said first gear for serving as an intermediate gear, and a third gear (10) having a diameter smaller than a diameter of said first gear and cooperatively connected to said first gear through said second gear by gear transmission, and a fourth gear (17) having a diameter which is larger than said third gear coaxially positioned with said third gear while in gear connection with said toothed member (17);
• and
• a third shaft member rotatably supporting said third gear (10) and as resilient member (14) provided on a protruded end portion or said third shaft member.