On some models, two leaf springs, above and below the knurled adjusting knob, help unlock the jaw when pressure on the handle of the wrench is released.

Today, aluminium might be substituted to reduce the weight of the body of the wrench, although the teeth and jaw remain steel.

Teeth and jaw kits (which also contain adjustment rings and springs) can be bought to repair broken wrenches.

[2] On 17 August 1888, the Swedish inventor Johan Petter Johansson (1853-1943) took out his first patent on the adjustable pipe wrench.

Back then, nut dimensions were poorly standardized, so each time a tradesman was out on a job, he needed a trolley to take a set of fixed pipe wrenches with him.