A surgical instrument includes a housing and an end effector spaced from the housing and transitionable between first and second conditions. A drive bar is coupled to the end effector and extends into the housing. The drive bar is translatable between first and second positions for transitioning the end effector between the first and second conditions. A handle assembly is moveable between initial and actuateds position for translating the drive bar between the first and second positions. One or more linkages couple the drive bar, the handle assembly, and the housing to one another by at least first, second and third pivots. At least one of the pivots is fixed and at least one of the pivots is floating. The second pivot is movable relative to the first and third pivots between an unlatched position and an over-center latched position for latching the end effector in the second condition.