Terminology is important when buying and using mechanical equipment. Proper terminology helps prevent confusion and helps you as the consumer get what you are expecting. So here are some fundamental trailer terms.
Hitch and Receiver
The hitch is the framework that bolts under the tow vehicle that holds the receiver. (Hitches that are welded to the vehicle's frame are illegal in most states.) The weight rating of the hitch will appear on a label, usually on the right side. If the label is missing, the rating should be stamped on the hitch.
The receiver is a hollow square tube that accepts a drawbar. (Drawbars are also called ball mounts.) Receivers come in various sizes that must match the size of the drawbar.
Hitch ratings are divided into "classes."
- Class I
Typical weight capacities: From 1,000 - 2,500 Lbs.
Has a fixed tongue or takes a 1-1/4 inch drawbar.
- Class II
Typical weight capacity: 3,500 Lbs.
Takes a 1-1/4 inch drawbar.
- Class III
Typical weight capacities: From 3,500 - 6,000 Lbs.
Takes a 2 inch drawbar.
- Class IV
Typical weight capacity of 10,000 Lbs.
Takes a 2 inch drawbar.
- Class V
Typical weight capacity of 12,000 Lbs or greater.
Takes a 2 inch or 2-1/2 inch drawbar, depending on rating.
Ball Mount or Drawbar
Ball Mounts or drawbars fit into the hitch receivers. Most are "drop hitch" type having an offset ball mount platform that allows the ball to be at the correct height so that the trailer is level when being towed. Level towing is important since a combination that is not level can grossly affect both steering and braking when an emergency stop is necessary.
Click the image for a quick and reliable way to determine what size drop you need.
Drawbars come in a wide variety of load ratings, depending on whether they are made from hollow tubing or are solid forged, as well as the strength of the material used in their construction. Drawbars will have their rated capacities on a clearly identifiable label, and also stamped into the unit if the label is missing.
It is important to also note that some drawbars have a reduced rating when used in a raised position (where the drawbar is oriented so that the ball mount is above the drawbar.) If you use an offset drawbar to raise the elevation of the ball mount, check the rating for that particular configuration.
Drawbar length is also important. A longer drawbar may be desirable when towing some short-tongued trailers where the tow vehicle's bumper may strike the trailer on tight turns. However the drawbar should not be so long as to prevent the safety chains from reaching the chain rings on the hitch.
Hitch balls come in three standard sizes, 1-7/8 inches, 2 inches and 2-5/16 inches. You have to use the correct size ball for each trailer's coupler or the trailer can (and will) uncouple while being towed. The size of the ball and its load rating will be stamped on either the top of the ball or on its base.
The ball shank size must be the same as the ball mount hole. Installing a ball having a smaller shank than the mounting hole is just asking for the ball to loosen up and fail! Also a proper lock washer must be in place with the mounting nut run completely tight.
Some painted balls can cause issues with some trailer coupler designs as the thickness of the paint can keep the ball from seating properly in the coupler. We recommend removing the paint from trailer balls and applying a dab of lubricant to prevent rust.
When selecting towing equipment or verifying that a particular set-up is capable of towing a particular load, be sure to check all three load ratings - of the hitch, drawbar and ball. Your weakest rating will likely be the point of failure. Also consider that a jerking load on a rough road applies a great deal more stress than smooth rated towing, so allow for a margin of safety when matching towing equipment ratings to loads.
U-Haul made a practical video to illustrate how to find the load ratings on your hitch, drawbar and ball.
The hitch pin is a small, often overlooked component that has the most important job in the hitch. If that pin comes loose, everything comes apart
Out West we have tumbleweeds and other brush that can blow across our highways on windy days. As a result we avoid hitch pins that are secured with hairpin clips. If something snags that clip, it can pull off and the hitch pin rattle loose. It has happened. We recommend using hitch pins that have positive locking devices.
Our emergency response team trailers all use pins with 1/8 inch holes and we use keyed-alike Master No. 7 padlocks. Nobody is going to steal our drawbars, but if we need to switch drawbars in a hurry everyone in the group has a key since we're all using the same lock.
Whatever method you choose to use, make sure your hitch pin can only come loose when you want it to!
Safety chains, also called breakaway chains, are your last line of defense if you have a hitch system failure or your trailer uncouples. Safety chains are required in most states and provinces. In many states you can be cited if an officer notices improper or missing chains and you could be criminally charged if your trailer uncouples, is not chained properly, and strikes another vehicle, pedestrian, etc.
Safety chains, in combination with a proper break-away braking system, will generally keep your trailer in-line behind your tow vehicle and allow you to come to a controlled stop without your trailer flipping over or becoming a deadly missile let loose on the highway. That's not to say that that it won't be a bit unnerving when the trailer comes loose and jerks the chains taught, however if you come to a controlled stop (as opposed to jamming the brakes and getting rear-ended by the trailer) you can usually resolve this emergency with little or no damage to the trailer, your vehicle, and to anyone else on the highway.
The illustration above shows the proper use of safety chains. They must be crossed under the trailer tongue to prevent the tongue from plunging into the pavement if the trailer uncouples. The chains must be long enough to allow the combination to turn without binding up, but not be so long that they drag on the ground. (You can twist the chains together or draw them through the hitch rings and clip them back onto themselves to take up slack if the drawbar is short and the chains tend to drag.)
Obviously safety chains need to be properly mounted to some structural element of the trailer tongue. The hooks or clips must be rated for the weight of the loaded trailer so that they won't fail during an emergency, and they should have clips or some similar device to prevent them from coming unhooked when towing over a rough road.
Most states and provinces require an automatic braking system that will apply any time that a trailer uncouples from its tow vehicle. Having brakes apply and the chains draw taught are critical to keeping an unhitched trailer under control and to prevent the trailer from shoving the tow vehicle and causing it to go out of control. However when conducting trailer safety inspections, failed or altogether missing automatic break-away brake systems are the most common safety problems that we find.
These systems utilize a stand-by battery to apply the brakes if a trailer uncouples and and the actuator cable is pulled out of the control switch. Older systems relied on 12-volt dry cell batteries to supply emergency brake power. Those batteries would fail with age and replacements could be difficult to locate, although better hardware stores often carry them. Nonetheless they would die, start to corrode, people would remove them and forget to replace them. Other times they just went dead, being long forgotten.
Newer systems utilize rechargeable batteries that are kept charged by the tow vehicle. These systems require 6 or 7 pin electrical connectors in order to have a lead dedicated to charging the break-away battery. Most newer vehicles come with circuits to power trailer accessories and rechargeable break-away systems. With older vehicles it isn't that difficult to run a 12 gauge wire from a battery connection to the trailer receptacle. The proper pin locations can be found here. Be sure to mount a 15 amp circuit breaker between this new wire and the battery connection.
The other major failure associated with this vital safety component involves drivers who don't know how to string the break-away "rip cord." It should be run through an opening on the hitch such as a chain hole, then back to the trailer or to a portion of the chain - long enough to allow the combination to turn without pulling the cable from the actuator, but short enough to pull free from the actuator if the trailer uncouples and the chains pull taught.
Most auto parts and truck accessory stores sell rechargeable break-away kits that can be easily installed to replace older dry cell kits. Kits are available that bolt directly to the trailer frame or clamp onto the tongue jack tower.
Even rechargeable batteries can run low, particularly if they are several years old or a trailer is seldom hitched and the batteries infrequently recharged. At least once a year as part of your annual trailer inspection you should "test" your system by pulling out the actuator and making sure your brakes engage. (You can return the actuator plunger after conducting the test and you can often recharge the break-away battery by plugging in your trailer for a couple of hours with your tow vehicle's accessory switch turned on.)
Some of the newer rechargeable systems even have a self-test feature that will tell you if the battery needs recharging.
The Trailer Coupler
There are several different coupler designs. All ultimately lock around the hitch ball and have to remain locked so that the trailer doesn't uncouple if you strike a bump or brake sharply. While the procedures vary for each design, some common elements do exist.
First we must know the size of the ball that the coupler requires. A coupler will fit over a size-smaller ball but the connection can come apart with drastic results.
There should be a distinctive label indicating the required ball size on or near the coupler. The ball size should also be stamped on the tongue or coupler in the event that the label disappears. However since stamped ball sizes might be hard to readily identify in the dark, it's a good idea to clearly label the proper ball size on couplers when the labels are missing.
Couplers don't always properly lock onto hitch balls, particularly if the trailer and tow vehicle are in a slight bind when coupling up. Always pull forward a short distance after hitching any trailer and double check that the coupler is properly locked and that safety clips or pins are properly inserted in order to prevent the coupler from accidentally releasing while under tow.