Push-pull torch

From GAWDAwiki

A push-pull torch is a type of MIG welding torch containing a separate set of drive rolls within the head of the torch to assist with pulling the filler wire through the torch liner. This type of torch is most widely used for feeding soft wires, such as aluminum, which may buckle within the liner, causing snags or bird-nesting at the wire feed unit.^[1]

References

1. http://www.bocindustrial.co.uk/bocindustrial/technical/glossary/a.asp