Pump pliers are a type of tool designed to be used in grasping, holding, compressing, or applying torque to an object. These tools may also be referred to as water pump pliers, Channellocks®, or tongue and groove pliers. The distinguishing characteristic of this type of pliers is the design using an adjustable fulcrum, which allows for the jaws to accommodate various sized objects. Depending on the size of the tool, the jaws may operate from a closed position to several inches (several centimeters) apart.
The pump pliers design features an elliptical opening that allows the pivot to slide and use any one of a number of channels that has been machined into the jaw handles. A protrusion or tongue in the opposite handle then slides through the selected channel, maintaining the desired space between the jaws of the pliers. This allows the user to grasp or compress objects of varying size comfortably, as the handles remain in the same relative position.
Pump pliers come in sizes determined by the length of the handles. The tool can be as short as 4 inches (about 10cm) and can be found in lengths up to 24 inches (about 60cm). Typically, homes and garages use pliers in the 6- to 12-inch (about 15cm- to 30cm-) range. Unlike the more common slip-joint pliers, the jaws on pump pliers are angled. The handles are offset by 45 or 60 degrees from the jaws. One advantage of this is the ability to maneuver in tight spaces in addition to allowing for greater adjustability.
This type of pliers is most often used in home plumbing or automotive applications. The varying width of the jaws combined with the offset handles makes it ideal for the tightening or loosening of water hose connections and spring-type clamps, both of which require a relatively wide jaw opening. The extended length of the handles combined with the ease of grasping offer increased leverage and compression force.
Pump pliers are commonly made from high carbon steel. They can also have chrome plating as a cosmetic feature as well as rubberized grips on the handle. Some pliers will be manufactured from brass to prevent sparking when working in explosive atmospheres or with objects containing flammable liquids. On rare occasions, inserts or other protective means are used to prevent damage to the object from the action of the jaws.
Pump pliers originally were designed for the tightening and removing of water pump packing nuts. The first design was marketed by the Champion–DeArment Tool Company under the trademarked name Channellock® in the 1930s. The company later changed its name to match its product.