In the process of being closed on an object the mechanism passes through a point of maximum tightest clamping and as the handle levers are closed further, the jaws release slightly. After being properly adjusted using a threaded screw, the pliers are brought to bear by cam action. Locking pliers remain clamped to an object without requiring continuous pressure on the handles based on the 'over-center' principle. This is the current spelling in the English speaking world except for the United States. The spelling ' vice' can be traced back to 1584, for the clamping sense of the word. This spelling is orthodox in the United States. The spelling ' vise' is mentioned in Samuel Johnson's 1755 dictionary. The same is true in the United Kingdom of the brand name ' Mole Wrench'. In the United States, the brand name ' Vise Grips' is close to a generic name for this type of pliers. Later, in 1955, in the United Kingdom, M K Mole and Son, a hand tool manufacturing company, under the managing direction of Thomas Coughtrie, began making nearly identical pliers.

Petersen in De Witt, Nebraska, United States in 1924. The first locking pliers, with the trade name Vise-Grip, were invented by William S.

History Locking pliers have a lever (on lower arm, right) to aid release from the locked position Locking pliers are available with many different jaw styles, such as needle-nose pliers, wrenches, clamps and various shapes to fix metal parts for welding. Locking pliers (also called Vise-Grips, a vice grip, Mole wrench or mole grips) are pliers that can be locked into position, using an 'over-center' cam action. A historic version of the Vise-Grip brand locking pliers

Vice grip clamp