What Parts Make Up a Weight-distribution System?

The weight distribution system adds to the standard weight-bearing hitch on your vehicle – typically a class III, IV, or V. A complete weight-distribution system is composed of a ball mount (both the shank and head assembly), spring bars, and mounted lift brackets.

What Parts Make Up a Weight-distribution System

Trailer Hitch

The trailer hitch, as you likely know, attaches to the frame of your vehicle and provides an opening (either 2”x2” or 2.5”x2.5”) for the weight distribution shank to slide into.

In order to be compatible with a weight distribution system, the hitch typically must be either a class III, IV, or V. It is important to check the label of your specific hitch, however, because not all class III hitches are compatible with weight distribution systems.

The hitch ball itself is typically not included with the purchase of a weight distribution system because the ball diameter required varies according to the capacity of your specific trailer and your coupler size.

Weight Distribution Shank

The weight distribution shank slides into the receiver hitch on your vehicle and provides the attachment point for the rest of the weight distribution system – i.e. the weight distribution head assembly.

The shank is available in many different sizes with varying lengths, drops, and rises.
To ensure safe, comfortable towing, the trailer should be set up on a level plane with your vehicle – the shank is designed to ensure this will happen.

Standard shanks typically have a maximum rise of 6” and a maximum drop of 2”. If you require a shank with different measurements, purchase a weight distribution system without a shank included (systems can be bought with and without this piece) and purchase the custom shank that you need separately.

Head Assembly

The weight distribution head assembly attaches to the shank and acts as a mount for both the hitch ball and spring bars. Depending on the head, it will likely accept either a round or trunnion spring bar.

The round bars slide into the head and are held in place via clips. The trunnion bars, on the other hand, slide into the head from either the side or the back. Some models also have a place where a sway control system can be mounted.

Upon installation, you often will need to adjust the angle of the head assembly in order to position the unit correctly. There are several ways this can be accomplished:

  • The block-style washer system utilizes a washer that can be rotated and positioned between the blocks of the weight distribution head. The washer is typically a hexagonal shape which is numbered with reference points in the event it ever requires adjustment.
  • The traditional washer system allows for the head assembly to be adjusted by sliding washers onto a rivet and inserting the spacer rivet into the head assembly itself. If the angle needs to be increased, you would simply remove the rivet, add another washer, and reattach. To decrease the angle – remove a washer. Repeat until you have the desired angle.
  • Finally, the serrated washer system is convenient in the sense that it does not require access to a rivet inside the head assembly. With this system, the head assembly can be adjusted by simply loosening a single washer/nut on the side of the head assembly, readjusting the head assembly to the desired angle, and then retightening the outside washer/nut until secure.
Weight Distribution Spring Bars

Weight Distribution Spring Bars

The spring bars are the part of the weight distribution hitch that evenly transfers the tongue weight pushing down on the rear of your vehicle to the axles of both your vehicle and the trailer. Most spring bars are made of flexible steel.

There are two main types of spring bars – each of which will be explained here. While there is no significant difference between the two styles, each does have slight nuances that may make one a better choice for your specific needs. If you have any questions about the two, please let us know – we would be happy to help.

Trunnion Spring Bars

Trunnion spring bars insert into the head assembly from either the side or the back. Because trunnion bars enter the head assembly from the side or the back – as opposed to the round bar, which enters from the bottom – they are ideal if you desire maximum ground clearance.

Round Spring Bars

Round Spring Bars slide upwards into the head assembly and are held in place with clips.

Lift Brackets

Lift brackets are utilized to hold the spring bars in place. The design of these varies significantly by manufacturer and model, but the purpose is generally the same. The most common system of lift brackets are known as a “snap-up” system.

In this system, chains are used to connect the spring bars to your trailer – with the chains then attached to the lift bracket that is mounted on the frame of the trailer. In order to achieve the appropriate level of tension in the spring bars, the number of chain links between the spring bars and lift bracket is monitored and adjusted if necessary.

Some companies have designed specialty brackets that reduce sway. Instead of using chains like the snap-up system, the spring bars rest directly on the lift brackets. Because the bracket is designed to hold the spring bar in place with friction – this system can reduce the amount of sway.

Finally, other companies like Blue Ox utilize a rotating latch kit. These brackets allow the user to hook up their system quicker and easier than the traditional snap-up system while also allowing for increased clearance. For these, the user only has to inset the chain into the bracket and rotate the handle on the unit until the correct amount of tension is obtained. This type of unit also prevents sway.

Louis Gilliland

Louis Gilliland

He began his career as a mechanic, working on cars, trucks, and trailers in Michigan for over 20 years. He quickly developed a passion for towing and hitches and began specializing in that field. Louis started his own business installing hitches and providing towing services, quickly building a reputation as one of the best in the state. He also began teaching and training other mechanics on proper hitch installation and towing safety.