Plierench

A Plierench is a hand tool that combines the parallel jaws of a wrench with the compressive handle-and-jaw action of a pair of pliers. Several designs exist, with the jaws and handles interacting via gearing or linkages. In some designs the relative position of the handles and the jaws is adjustable, whereas in others it is fixed.

Also features a wire cutter and screwdriver/pry tool.

Pros
The benefits of the plierench stem from the jaws and their interelationship with the handles. The jaws are generally smooth, lacking the teeth seen on many pliers, and so are less likely to damage the work piece. The use of the handles to change the distance between the jaws eliminates the need to size the jaws in a separate step, before using the tool - sizing is done as the tool is applied. Further, it means that the strength of the tools grip is variable, allowing the tool to easily grip delicate items or firmly grip robust ones.

The moveable jaw is replaceable with other jaws suited for different purposes. There is a jaw specifically designed for pipes/plumbing, a tubing cutter jaw, a large span jaw, a wire bending/spring making jaw, and a jaw inserted from the opposite direction into the head allows the tool to be used as a powerful spreader.

The geared teeth at the top of the adjustable handle mesh with geared teeth at the base of each type of jaw. Thus the user's grip strength is needed only to hold the handles together - which takes little force. s long as the handles are together, the gears are meshed, and the tool cannot lose its grip. Gear teeth would need be broken off for the plierench to slip when properly used.

A ratchet action can be accomplished by the user letting loose on the lower handle while rotating back from a turn on the work. Since little strength is required to hold the handles while applying force, an easy ratcheting can be accomplish.

Due the the highly multiplied gripping power made possible by the geared design, this tool can easily be used for jobs such as removing screws/bolts with stripped heads (providing a grip can be obtained on the head), removing nails from boards, etc.

Cons
The jaws also represent a design weakness, however, as their smoothness means that as the plierench is turned (to tighten a nut, for instance), the work piece pushes the jaws apart. Thus, a plierench cannot apply large amounts of torque. Similarly, its gripping power is related to the strength of the user.

Polite refutation to this con: When used properly, the jaws cannot slip, require little force from the user's grip to hold the geared teeh in place (simply holding the handle together with little force), and will allow much more torque to be applied that other tools typically used. Experience properly using this tool (according to instructions) shows the above to be true.

Addition to polite refutation. Reading the instructions is a must. The 5 second learning curve totally alleviates/removes any concept of the jaws being pushed apart by the work. This tool was designed to combat the very concept while also making it unnecessary to squeeze the handles with any amount of force (!). Normal pliers need a strong grip to keep the work secure, the Eifel plierench uses a rack and pinion system instead. The top "action end" of one handle is geared to mesh into the "rack gear" on each swappable jaw's bottom edge. When used properly, the object between the jaws would have to break the metal of the gear teeth to open the jaw! A rubber band can literally hold the two handles together, keeping the grip, since the only force needed is simply to keep the handle's top gear teeth from rotating backwards and releasing the work. I even use mine for a quick clamping device using just a rubber band.

Legitimate Con: Wires tend to slip through the  wire cutter jaws rather than being cut.