You’ve probably heard them called everything from tension castings to those thing-a-ma-jigs that the key rods screw into. The term I grew up with is lugs, and without them we would still be tensioning the heads with rope.
Drum companies seem to change their design every year but there are a few lugs that still remain unchanged (Fig. 1): Slingerland (beavertail; Sound King), Ludwig (Classic), DW (turret), and Rogers (beavertail).
There are many different types of lug tensioning systems. I will be writing about the two main types, tube and case (Fig. 2). Tube lugs require you to thread the tension rods directly into the lug. When working with tube lugs you have to be very careful to line up the tension rod, and use a little lug lube, to help prevent the possibility of cross threading. Case lugs consist of three basic parts: The case, swivel or lug nut, and the spring (vintage style) or hard fiber/rubber retainer (modern style) (Fig. 3). Case-type lugs are self-aligning and are a lot more forgiving than tube lugs in the cross threading department.