2-way vs. 1-way truss rods

[Izaac Walton]

What's 2-way about the 2-way truss rods, i.e. how do they work? Better, or just different, from the traditional 1-way truss rods?

Could a 2-way be used to replace a 1-way truss rod?

[sunburst]

There are several different types of "one way" rods, and several types of "two way" rods.
They work different ways.

A standard rod could be replaced with a "two way", but we're talking major surgery here.

[Chris Baird]

A compression rod works by compressing the wood in the back of the neck hence causing tension on the fretboard side. The two way rods work by actually arching themselves such that the ends of the rod push towards the back of the neck and the middle pushes against the fretboard. The term "two-way" is somewhat misleading as they are never used the other way although they could be. I'm not sure which is more effective, the two way seems to have more mechanical advantage as it takes fewer turns to get the desired result. I do like that the adjustment cavity is very small with two way rods.