The skateboard truck consists of four basic components: the hanger, baseplate, kingpin and bushings. Almost all trucks on the market contain these components or variations of them.
The hanger is the part that holds the axle. The hanger is generally cast directly around the axle, making the whole component stronger and reducing axle slippage. This component takes the brunt of the force during grinding tricks. When a rider grinds on a railing or a curb, he is riding on the hanger, between the wheels. This means that the hanger is worn down quickly during regular usage. It must be made strong and hard to inhibit this wear as much as possible.
The baseplate is the interface between the deck and the wheels. It is attached to the deck with bolts in a standard four-hole pattern. The other components mount onto the baseplate.
Holding the hanger to the baseplate is the kingpin. This bolt is mounted on the baseplate, with the hanger held on to it by a nut. There is some space between the kingpin and the hanger, allowing the hanger some freedom to rotate.
Between the hanger and the kingpin are the bushings. These urethane rings fit snugly around the kingpin, creating a tight fit between the hanger and the kingpin. Because they are soft and malleable, the hanger retains its freedom to rotate, as long as sufficient force is applied.
The hanger is mounted in such a way that it has two pivot points. A point similar to a ball joint holds the hanger directly to the baseplate. The other point is around the kingpin, held in place by the bushings. This creates an axis of rotation at a 45 degree angle. When a vertical force is applied, the axle deflects around this axis, creating a horizontal and a vertical component. Having the axis of rotation at 45 degrees separates the force into two equal components. The vertical component will be the same magnitude as the horizontal component. The horizontal deflection creates a turning radius. In this way, the user can turn by applying a vertical force.
The nut on the top of the kingpin can be used to adjust the truck to different riding styles. By tightening this nut, the bushings are compressed, creating a snugger fit between the hanger and the kingpin. This means that more force is required to turn. The truck is tighter, turns less easily and is more stable. Novice users like to have more stable trucks. In addition, in professional competitions, tighter trucks are desired for events such as the half-pipe, where precision aerial tricks are performed. On the street, however, most users prefer to have a looser truck, with more manoeuvrability. The nut allows each user to adjust the performance of the truck to match his or her riding style. The nut is a standard size, allowing anyone to change the characteristics of their truck with a simple socket wrench or skate tool.
Additionally, different types of bushings can be purchased. These bushings have different material properties and affect the performance of the truck in the same way as tightening the kingpin nut does. By using different bushings, users can adjust the truck more permanently, while still allowing for minute adjustments of the kingpin nut.
Other small components are also used in most designs. Plates are used to hold the bushings in place. Riser pads made of rubber are often mounted between the baseplate and the deck to absorb shock. A plastic cup is used to create the pivot joint on the Tracker Hawk analysed in this project.
