Kingpin

The kingpin is the bolt that runs through the center of your skateboard trucks, and holds the trucks together. The kingpin sticks up through the baseplate and runs through the bottom bushing, the hangar, top bushing, bushing cap, and is then secured with a nut. Most kingpins are a fat hex-headed bolt, but there are many kinds of kingpins out there, including inverted kingpins, which is the preferred option for freestylers so that the kingpin doesn't dig into your calves during no-handed pogos.