Pump pliers

For the manufacturer named Channellock, see Channellock (manufacturer). Pump pliers, also known as tongue-and-groove pliers, and by the trade name Channellocks, are long-handled pliers whose jaws are set at an angle from the handles. Like all pliers, squeezing the handles squeezes the jaws, but the pivot point for the jaws and handles is adjustable, enabling the pliers to grip widely disparate sized items.

History
Tongue-and-groove pliers were developed in 1933 by Howard Manning, chief engineer for the Champion DeArment Tool Company. He used a curved tongue-and-groove mechanism for a pivot, but left the mechanism open at its ends; opening the handles all the way enables the user to align the tongues with different grooves, changing the pivot point and the distance between the jaws. This design gave the pliers the ability to grip a wide range of items. Manning also gave the pliers long handles for increased leverage.

Champion DeArment marketed the tool as Channellock pliers, becoming so synonymous with the tool that in 1963 they made it their company name.

Modern pump pliers
Since then, differing mechanisms have evolved for the adjustable pivot, but in each case the basic layout of the tool, with angled jaws, long handles, and a multi-position pivot, remains. Like most pliers, the pump pliers function as a pair of first class levers, joined at a common fulcrum.