1. Sway
   Raise up
2. Shake
   Dive

Having too much tongue weight in relation to gross trailer weight can cause the hitch of the trailer and the rear axle of the tow vehicle to dive. <a href="http://auto.howstuffworks.com/auto-parts/towing/equipment/hitches/towing-weight-distribution-systems.htm">How Weight Distribution Systems Work</a>

1. Maximum towing capacity
   Curb weight
2. Gross trailer weight
   GAWR

Towing weight distribution systems should be used when there is too much tongue weight in relation to the gross trailer weight. <a href="http://auto.howstuffworks.com/auto-parts/towing/equipment/hitches/towing-weight-distribution-systems.htm">How Weight Distribution Systems Work</a>

1. 0.25
   0.75
2. 0.5
   0.1

Towing weight distribution systems should be used when your trailer weighs in at more than 50 percent of the towing vehicle's weight. <a href="http://auto.howstuffworks.com/auto-parts/towing/equipment/hitches/towing-weight-distribution-systems.htm">How Weight Distribution Systems Work</a>

1. Gross trailer weight
   Maximum payload
2. Cargo carrying capacity
   Curb weight

Towing weight distribution systems are required by law once a certain value has been reached for the gross trailer weight. <a href="http://auto.howstuffworks.com/auto-parts/towing/equipment/hitches/towing-weight-distribution-systems.htm">How Weight Distribution Systems Work</a>

1. Maximum spring bar
   Round spring bar
2. Trunnion spring bar
   Ultimate spring bar

A trunnion spring bar can increase the towing weight distribution's weight rating. <a href="http://auto.howstuffworks.com/auto-parts/towing/equipment/hitches/towing-weight-distribution-systems.htm">How Weight Distribution Systems Work</a>

1. Weight minimization
   Cruise control
2. Sway control
   Stainless steel spring bars

2-in-1 weight distribution systems also come equipped with sway control. <a href="http://auto.howstuffworks.com/auto-parts/towing/equipment/hitches/towing-weight-distribution-systems.htm">How Weight Distribution Systems Work</a>

1. Spring bars
   Head assembly
2. Brackets
   Shank

The shank is the part of the weight distribution system that is plugged into the hitch receiver. <a href="http://auto.howstuffworks.com/auto-parts/towing/equipment/hitches/towing-weight-distribution-systems.htm">How Weight Distribution Systems Work</a>

1. Head assembly
   Chains
2. Sway control
   Brackets

As the tongue weight is pushing the weight distribution system's spring bars down, the chains are pulling them up. <a href="http://auto.howstuffworks.com/auto-parts/towing/equipment/hitches/towing-weight-distribution-systems.htm">How Weight Distribution Systems Work</a>

1. The length of the trailer
   Curb weight
2. The angle of the spring bars
   The size of the hitch receiver

When installing a towing weight distribution system, it is important to note the angle of the spring bars, as well as the change in the height of the wheel well rims. <a href="http://auto.howstuffworks.com/auto-parts/towing/equipment/hitches/towing-weight-distribution-systems.htm">How Weight Distribution Systems Work</a>

1. Shank
   Spring bars
2. Chains
   Brackets

When installing a towing weight distribution system, the head assembly should be mounted onto the shank. <a href="http://auto.howstuffworks.com/auto-parts/towing/equipment/hitches/towing-weight-distribution-systems.htm">How Weight Distribution Systems Work</a>