Abstract: A mechanical power amplifier for a vise having housing means and a primary member and a secondary member mounted therein. At least the primary member is movable in the housing and transmits a force to force amplifying and transmitting structure also mounted in the housing to effect both an amplification of the force transmitted thereto as well as a transfer of the force from the primary member to a force transmitting member. The force amplifying and transmitting structure includes a pair of bell-crank levers arranged in a mirror-image manner relative to the center axis of the housing. Each bell-crank lever has a long lever arm with a wedge surface thereon and a short lever arm. The wedge surface engages a cam surface on the primary member and is movable laterally in response to a movement of the primary member. A pair of laterally spaced rollers are positioned on opposite sides of the center axis of the housing and engage the short lever arm and an abutment surface on the secondary member.