Abstract: A clamping mechanism for an impulse sealer includes a pair of drive arms pivoted on a flat base member and a pressure arm pivoted about the same pivot between the drive arms. Complimentary pressure members are located at the free ends of the drive arms and pressure arm for clamping a member to be heat sealed. A pair of levers are pivoted intermediate their ends on the drive arms between the clamping member and the pivot. The levers are comprised of two arms disposed at oblique angles relative to each other with the end of the lower arm sliding on the flat surface of the base member. The free end of the upper arm of the lever is connected to the pressure arm at a point between the clamping member and the pivot by means of a connecting rod so that depression of the drive arm will cause the ends of the lower lever arm to slide along the surface of the base member.