You have a deck, wheels, bearings, but you need to attach these all together to have a skateboard, that’s what skateboard trucks are for.
Trucks usually consist of about 6 different parts, the baseplate, which is screwed to the deck, the hanger which sits inside a pivot cup on the baseplate on one end and is bolted by the kingpin on the other end with rubber bushings. The axle for the wheels runs through the center of the hanger.
Bushings are available in different degrees of hardness. Harder bushings mean less wobble and turning ability, softer bushings make it easier to turn. The kingpin can also be adjusted to restrict or allow movement of the hanger, which affects the control of the board for turning. Different styles require different settings so adjust your trucks by loosening or tightening the kingpin until you get the best feel.
Skateboard trucks are mounted on the deck with the kingpins facing toward the center.
When choosing trucks, be sure to consider the weight (a lighter skateboard is easier to control for tricks) and the material and thickness of the hanger. Cheap hangers can snap under pressure and thin hangers can be ground down quickly if you are into 50-50’s, 5-0’s or other grinds.Skateboard Trucks - A guide by Skatessentials