is closed while inserting it into the hole. It snaps open when it
enters the hollow cavity of the wall, as seen in Figure 150.
Spring-wing toggle bolts
1-13. Hinges. All hinges are used to make a movable joint between two
pieces of material. A hinge consists primarily of a pin and two
plates. There are three most commonly used hinges: fullmortise,
halfsurface, and fullsurface. Figure 151 shows the basic design
of a common door hinge.
Common door hinge