A Brief History of Truss Rods
Back in the 19th century guitars were always strung with gut strings, similar to the nylon strings on modern classical guitars. The strings were lower in tension and the guitars had higher actions, so the necks of guitars could stand up to the tension and the guitars remained playable.
The advent of Steel Strings on guitars brought with it the problems of bent necks that couldn't be tamed and high, unplayable actions. Something needed to be done!
In 1921 the first truss rod was patented by Thaddeus McHugh, an employee of Gibson Guitars, though there had been work on truss rods as far back as 1908. This was the simple 'bent rod' truss rod still used these days.
Since the early 20th century there have been many types of truss rods developed. There are double-action truss rods and the newer types can be installed into a straight channel, making them easier to install than the original bent-rod types.
