If you are thinking about buying your very first travel trailer and making the first steps into the RVing world, you will be faced with many terms that might be unknown to you.
Many of the terms unique to the travel trailer world are related to towing and all the required systems. For example, what exactly is a “weight distribution system”?
The weight distribution system is a type of towing hitch which does what its name suggests and distributes weight. It transfers the trailer’s weight from towing vehicle and trailer’s bumpers and instead distributes it to the axles of both the tow vehicle and the trailer.
But, when it comes to these hitches, there are more things you should know about them, such as how they do what they do, and when will you need them.
Types of Hitches
Because it is a type of hitch before we get into details of the weight distribution system you should be aware that it is not the only type. There are three main types of hitches:
- conventional hitches
- weight distribution hitches
- 5th wheel hitches
Conventional and weight distribution types are relatively similar to each other. Still, the latter is an order of magnitude more complex devices, because of which they are considered a separate type.
Weight Distribution System Defined
A weight distribution system is a type of trailer hitch that is able to take part of the weight of a trailer from towing vehicle’s rear axle to its front one.
When you are towing a travel trailer, part of its weight is pressing the hitch, and this can make the towing vehicle squat. A situation in which suspension is so compressed that the front of the vehicle gets raised.
In such a situation, your headlights would point too high, being a hindrance to other drivers, but also the front wheels of the towing vehicle will have lower traction.
With lower traction comes severe understeering and longer braking distances. The weight distribution system counters this and distributes part of this weight from the rear suspension to the front of towing vehicle.
Weight Distribution System Requirements
Because a trailer can disrupt the weight balance of a towing vehicle, when the weight distribution system is required is a specification that you can find in the user manual of your vehicle. It is a minimum weight of a trailer above which you should have it.
But, if you do not have the manual anymore, the rule of thumb is that you should have it if the trailer’s weight is more than half of the weight of the towing vehicle.
Parts of a weight distribution system:
The weight distribution system is made of several parts besides the trailer hitch receiver which is common with the conventional hitches, and mounts on the frame of the towing vehicle. These components are:
- weight distribution shank
- head assembly
- spring bars
- frame brackets
Weight Distribution Shank
This part slides into the towing hitch receiver tube and provides mounting points for the head assembly. It provides the ability to adjust the drop and raise of the hitch.
Another vital thing to know is that it can be purchased separately from the rest of the system, which provides greater adjustability for length, raise, or drop.
Head assembly provides the hitch ball for attaching the trailer’s tongue, but also the attachment points for the most important part, spring bars.
Head assemblies differ between manufacturers, but also models of weight distribution systems, usually they must be used with matching spring bars. Many head assemblies also provide attachment points for sway bars too.
Spring bars (curtmfg.com) are the most important part of the weight distribution system, they are the part that causes the transfer of the trailer’s weight from towing vehicle’s rear to the front axle.
They can come in three different shapes, round, square, and trunnion; and their shape decides with which head assembly they can be used.
The frame brackets are used to connect the other ends of spring bars to the frame of a trailer and provide the second anchor point for creating the tension in the bars that provides them the leverage needed for proper function.
The most common type are brackets with tension chains, but some models have special sway-control brackets that steel flat bars instead of chains.
Types of Weight Distribution Systems
Based on the shape of the spring bars, there are two types of weight distribution systems:
- round bar
- trunnion bar
The second type includes systems that have both trunnion and square shapes spring bars. The main difference between these systems is the amount of clearance under the spring bars.
Round bars have an L shape, which decreases the clearance. But also, trunion bars can have slightly higher capacity.
How does the weight distribution system work?
The weight distribution system works on a simple principle that the spring bars are stiff and much longer. When the trailer’s tongue pushes on the ball mount of the head assembly to which bars are connected, the downward force is applied to the spring bars.
This force is transferred to the connection point of spring bars and frame bracket chains.
Here, this force causes the further end of bars to pivot upwards around this point because their length cannot be changed. This leverage forces the head assembly and the rear end of the towing vehicle to move up.
This changes the direction in which the force of the trailer’s tongue acts on the hitch ball and effectively distributes its weight to the front wheels of towing vehicle.
Does it increase the towing capacity?
No, weight distribution systems do not increase towing capacity. Instead, they allow you to maximize the use of the rear axle capacity of the towing vehicle, and so reach the maximum towing capacity in a safe manner.
Does it increase hitch weight capacity?
No, the weight distribution system doesn’t have any impact on tongue weight nor on hitch weight capacity. It changes how the forces are distributed after the hitch.
The force of the trailer tongue doesn’t push the hitch straight downward, but at a slightly acute angle, the distribution system makes this angle more acute. But this force, i.e. tongue weight, remains the same.
Does it control the sway of the trailer?
The weight distribution system provides a small degree of sway control due to the stiffness of spring bars, but that effect can be ignored.
Proper sway control is achieved with special sway bars that can be installed on or purchased with some weight distribution system models.
Towing a travel trailer can include some devices that improve its safety and comfort. Which is the reason why you should know what is a weight distribution system.
It is a type of towing hitch that counters the trailer tongue’s downward force on the hitch which can make the towing vehicle squat.