There are three general categories for consideration with respect to "Good" trailer design: Strength, Stability, and Versatility (or function). A utility trailer has a flat bed with sides that carries all sorts of “stuff”. There are a lot of basics that make the trailer pull well, and carry the required “stuff” as needed for years.
Trailer strength is the first aspect of good trailer design. In utility trailer strength is important because they are frequently loaded or overloaded. The utility trailer must be sufficiently strong so that it can serve well no matter what the requirement. Some factors relating to trailer strength are given below:
· Load capacity
· Construction(the way it is built)
· Basic trailer layout
The maximum load for which the trailer is designed to carry will determine much about the strength of the trailer. It will also determine how strong the trailer should be. Trailer strength should be judged with respect to its intended capacity.
Construction is a big factor in strength. If the trailer is bolted together, joints will act differently than if it is welded. In some areas it is desirable to use bolts -- especially with options, and when things need to be removed or adjusted. So, when bolts are used they should include methods like lock nuts, keys, tabs, etc. to keep the bolts from vibrating loose.
Materials and constructions techniques should be adequate. Most trailers will indeed carry the specified load, however, if the weight is not distributed well, it can seriously damage the trailer and/or the towing vehicle.
Basic trailer layout :
The basic layout of the trailer can be a good estimation of strength and will also affect stability in operation. Few things should be noted: Length of the tongue, axle location, strong rear member.
Length of the tongue: The tongue should be long enough to allow a reasonable turning radius and clearance to the vehicle when backing. If the tongue is short, it may be an indication of weakness or shortcuts in the design. A longer tongue is nice for extending the axle separation for stability and bounce.
The axle should be behind the load center for stability. Often trailers have the axle at or behind the center of the bed. For maximum versatility axle position should be behind the center of the bed for proper adjustment of the axle.
Strong rear member:
The back most “bumper” of the trailer should be strong. Usually the loading and unloading occurs over this member, so it should be disproportionately larger (stronger) than the other cross members.
There are many components of a trailer that contribute to strength or weakness - or be indications of short-cuts or cheapness in the design. There are few things to look at:
· Ball receiver and hitch should be appropriately sized for the trailer capacity.
· The ball receiver should be made for a ball of adequate size.
· The axle should be sized for the trailer load capacity.
· Axle springs should match the trailer.
· Wheels must meet or exceed trailer load capacity.
· Tires are key on several levels. Tire ratings must match trailer capacity.
· Trailer brakes is largely dependent on the tow vehicle and anticipated loads.
· Tail lights, running lights and reflectors should be in place around the trailer.
There are dozens of factors related to towing stability. For making a trailer stable no one factor is absolute all has an affect. Few of the common things are:
· Load distribution
· Trailer length
· Trailer brakes, calibrating the brakes
· Dynamic loads
· Center of gravity
It is the most common cause of stability and the easiest to correct. The trailer load should always be reasonably distributed from side to side. Don't put a lot more weight on one side or the other. Center the load on the trailer as much as possible. Load distribution extends beyond just how a load is put in a trailer. When a trailer is hitched to a tow vehicle, they become a system and the dynamics of the system are what makes stability. For the tow vehicle, "Motor Boating" is a big stability concern. load distributing hitches can also be used to level the trailer with respect to the tow vehicle.
Trailer length and length with respect to width is another stability factor. Longer trailers typically tow better -- or more accurately, a greater separation between the rear most wheels of the tow vehicle and the fore most wheels of the trailer. A long tongue can facilitate such separation. Trailer length in the context of width of the trailer with respect to the tow vehicle and with respect to length . In general, the wider the trailer, the more it will benefit from length. Another length factor is the distance between the rear wheels of the tow vehicle and the hitch point. When this distance is shorter, the trailer can't "wag" the tow vehicle as much, nor do the "bumps" of the tow vehicle affect the trailer as much. A hitch at the back of a really long overhang will have a negative effect on stability.
Trailer brakes, and calibrating the brakes:
The brakes and application of the brakes need to be appropriate for the load and the trailer size. This is less of an issue with electric brakes than with surge type, but it applies to both. Numerous issues with setting and calibrating surge brakes have caused several states to consider banning their use. Check local regulations before buying a trailer with surge type brakes.
It can have a significant effect on stability. If a large, heavy pipe is carried untied, it will r
oll from side to side or front to back with motion of the trailer. This constantly changing load makes the trailer move. If the dynamic load is small compared to the weight of the trailer, it may not be so important, but if the moving load is a large, the effect can be quite important. In general, the load should be secured as much as possible to accommodate stability.
Center of gravity:
Center of gravity is another important consideration. In general, a lower center of gravity helps stability.
In utility trailer the necessary options that make the trailer versatile are so highly dependent on the intended use. Some factors related to versatility are:
· Suspension type
· Breakaway brake activation
· Type of Hitch
· Tongue Jack
· Safety chains
· Trailer Top
· Tail Gate
· Tie points
· Tongue box
Suspension Type is sometimes overlooked as an option because leaf springs are so common. The typical leaf springs on pivots are the most common, but slipper type leafs are also popular -- especially in high capacity and multi-axle trailers.
Breakaway brake activation:
It can be a nice safety feature. Basically these devises activate the trailer brakes if the breakaway connection comes disconnected.
Type of hitch:
The Type of Hitch used to pull your load is certainly an option. It's a given with a particular trailer as to using a bumper type hitch or a goose neck or a 5th wheel.
Tongue Jack also has options like whether it has a wheel or not and whether it telescopes or not. The size of a tongue jack wheel will determine how easily the trailer can be moved on concrete, gravel or dirt surfaces. For trailers to be stored on dirt surfaces, a larger tongue jack wheel may be desired.
Safety chains are required in most places. The chains must be sized appropriately for the trailer.
The top can be canvas, or hard; it may be permanent or removable. A top may lift to gain access or it may be stationary.
In utility trailer a tail gate is an option to consider. There are all different types of tailgates and they can be made of various materials based on the requirements. Some just hold stuff in. Some fold down to become a rear ramp for access into the trailer. Some are solid, some are open to allow wind to pass through.
Tie points :
Tie points should be located in convenient locations based on the intended loads, adjustable positioning Tie-down points are especially important with open utility trailers. Sometimes the tie points are part of the frame, sometimes attached to the sides. Sometimes they are rigid, sometimes they fold away.
There are all sorts of fenders available from stamped steel to plastic, fiberglass or wood. They come square, round or as pasture fenders. State or province may regulate the need for fenders.
Tongue box can make a nice addition to a trailer. As with this box, a nice weather tight place to put tools, tie-downs and other items can be very useful. Boxes such as this can also be added to the sides just in front or behind the wheels, or just under the bed.
Finally, every trailer designer has some nifty options available with their trailers.