Quad Roller Skate Trucks
by Dave VanBelleghem

An introduction to trucks for quad roller skates. Includes the definition of a truck, how to use your trucks to steer, how to adjust your trucks, and information about single action and double action trucks.

What Is a Truck?

Before describing the various types of trucks, it may be helpful to know exactly what a "truck" is. The truck is the piece of metal, usually aluminum, that the axle passes through. It has a pivot pin that inserts into the pivot cup on the hanger (more about the hanger later). It also has a circular "boss" section which has a machined out area for the cushions to sit in. There is a hole in the center of the boss for the kingpin bolt to pass through.

Steering Quad Skates

Steering on a quad skate is done by one of or a combination of two methods. The first is by picking your skate up off the floor while you're rolling and putting it down pointing in another direction. The second is by leaning your weight to the inside or outside of your foot. The cushions flex and allow the axles and wheels to tilt. At the same time the truck will try to rotate about the kingpin bolt. The pivot pin only allows it to rotate so far. The front truck and rear truck will rotate in opposite directions around their respective kingpins. If the skater is leaning to the right the right hand side front and rear wheels will move slightly towards each other, while the front and rear wheels on the left side will move slightly away from each other. This combination of movements forms an "arc" (not Joan's or Noah's), a part of a circle which causes the skate to roll towards the right. Leaning to the left causes the same sort of movements, only in a mirrored image so that the skate rolls to the left. Pretty nifty idea James Plimpton came up with in 1863.

There are two basic types of trucks, the single action and the double action.

Single Action Trucks

The single action has one cushion, usually made of rubber or polyurethane, that sits top of the boss on the truck. The double action has two cushions, one above and one below the boss. The single action has more of a snap type action to it then the double action. It was initially developed for use by roller derby skaters, as it tends to give a feeling of clinging to the skating surface and rolls well over non flat surfaces such as banked tracks and roads. Single action trucks are very sensitive to the slightest move of the skater's foot and are not usually used for artistic or dance type skating which requires more control.

Double Action Trucks

The lower cushion on the double action truck helps to dampen the movements a little bit and make one footed spins and trick movements more manageable.

Adjusting Your Trucks

The looseness or tightness of your trucks determines how easy they are to steer. The tighter the truck, the more effort it takes to make the cushions flex and the wheels to turn in the direction you want. Speed skaters generally have their trucks set fairly tight with just enough flex to allow them to turn. The tighter setup allows more of the energy from the skater's leg to be transferred through the truck to the wheels on down to the floor. A looser setup would absorb some of the energy and make the skating stride less efficient for transferring power.

A roller dancer, slalomer or roller hockey player would need more movement in the cushions to allow for the constant change in direction needed to perform quick stops, turns and maneuvers, so would require a looser setup of the trucks.

The tightness of the trucks is controlled by the kingpin bolt. There are two basic types of kingpin setups. The first is called the conventional or standard setup. The cushions, retainers and trucks are loaded onto the kingpin then the action locknut is threaded onto the end of the bolt. The bolt is then threaded into the hole in the bottom of the plate. The pivot pin on the truck goes into the pivot cup on the plate bottom. (More on pivot pins in a minute). While holding the action locknut in place with either your fingers or a locknut wrench, the kingpin is threaded into the plate until the pieces start to snug together. The kingpin head will have a slotted head, a hex head or an allen key slot. Flex the axles of the truck back and forth with your fingers to check for tightness. If it needs to be tighter thread the bolt in some more. If too tight loosen a bit. (Righty tighty, lefty loosey as they say). When it feels about right tighten up the action nut with the wrench.

Check again to see if the truck feels about right. If ok then tighten the action nut good and hard. Some advise tapping the wrench with a hammer, but that is a bit of overkill and could result in stripping the threads. The action locknut must be kept tight so it's a good idea to check it every few skates. If it loosens there will be a small gap between it and the plate that will allow the kinpin to flex and eventually snap from metal fatigue. An action locknut wrench is typically an 11/16 inch open end wrench with jaws about one half the thickness of conventional wrench jaws. The jaws on a regular wrench are too thick to fit into the space between the retainer and the plate. The locknut wrench is on the left, the standard wrench on the right.

You can buy cheap locknut wrenches from skate retailers for a few dollars that are simply a stamped out piece of metal...

...or you can buy an expensive Snap-On one for around 100 bucks. I'm too cheap to do that so I rummaged around at a flea market and found a suitable wrench for a dollar. If you're on good terms with your mechanic he might let you borrow his 11/16 tappet wrench for a few minutes to do the job. The vast majority of metal (aluminum, magnesium, titanium) quad plates use the conventional kingpin setup.

The second type of kingpin arrangement is the reverse kingpin setup.

This type is used on virtually all the plastic or Zytel type plates (Sunlites, Probes, etc.). In the reverse setup the kingpin is slid down through a non threaded hole in the top of the plate. The head of the bolt is usually glued into the hex shaped hole in the plate. Then the retainers, cushions and truck are slid onto the other end of the bolt. Then a nut is threaded on to keep the pieces on the bolt. Tighten the nut to your preference then go and skate. A very simple setup. No action locknut is used next to the plate. Since the plastic plate has some flex in it this takes the stress away from the kingpin. Unless you're doing something severe snapped kingpins are a rare occurence with a reverse setup.

OK. What is the hanger? The hanger is simply the part of the plate that the kingpin and pivot pin "hang" from, or in other words the area with the hole for the kingpin and the hole for the pivot pin (the pivot cup). In the case of a molded or cast plate the hanger is built into the plate.

Some plates such as the Sure-Grip Century and XK-4 use a separate mini skateboard style hanger that is riveted onto a nicely machined base plate.

Now, what is the pivot pin? That is the pointy part of the truck that fits into the pivot cup on the hanger.

The less expensive plates, though not necessarily flimsy ones, use a pivot cup with a replaceable rubber bushing set into it. The pivot pin sits inside the bushing. It keeps the pivot pin from flopping around thus giving control and helps to absorb bounces and shocks.

The semiprecision type of pivot pin has a ball on the end of it that fits into a socket. It gives a more controlled and responsive movement. The precision type of pivot pin has an adjustable end to it so you can tweak it into the exact position you need. This type is found on really pricey plates.