How to Tow a Trailer Safely and Avoid Disasters
Hauling trailers can be dangerous, but for many people in the trades it’s necessary. We talked to an expert who’s been in the trailer business to learn all of his secrets.
Grease the bearings
When asked what is the No. 1 cause of trailer breakdowns and accidents, without hesitating, our trailer expert said, “Bearings. People don’t maintain their bearings.” Over time, bearing grease breaks down and loses its ability to lubricate and dissipate heat. Many manufacturers recommend repacking wheel bearings in grease every year or 10,000 miles, whichever comes first. Under-maintained bearings can overheat, eventually causing them to seize, start on fire or separate completely so that the wheel falls off while you’re driving…not good!
Our expert is not a fan of bearing caps with a built-in grease fitting. Adding grease through the cap can permanently damage the rear seal. Plus, this method fills the axle/spindle area, which should remain dry, with grease. Removing the old grease and cleaning the bearing are vital components of repacking bearings, and both are often neglected when people rely on these caps.
Always Pin the Coupler
The second most common trailer disaster is caused by a trailer coupler coming loose from a ball mount. Hooking up a trailer to an undersize ball is the usual culprit…don’t do that!
A loose locking lever is another common cause of losing a trailer. As the trailer bounces down the road, the locking lever can wriggle up into the unlocked position. A pin will keep that from happening. The wire lock pin shown here costs a few bucks at home centers, so there’s no excuse for not using one.
A Trailer Should Ride Level When Loaded
Trailers are designed to ride level. A trailer that’s high or low on one end or the other won’t pull as smoothly or as safely. Also, hauling a tandem axle trailer unevenly will cause more wear and tear on one set of tires and suspension than on the other.
The “drop” of the ball mount determines how high or low the tongue of the trailer will ride. Here’s one way to estimate the amount of drop your ball mount needs: Measure up from level ground to the top of the receiver, then measure up from the ground to the bottom of the coupler on the trailer; subtract the first measurement from the second. But that will only get you close.
The problem with this method is that it doesn’t take into account the tongue weight of your particular trailer or the stiffness of your truck’s rear suspension. The only true way to get your trailer to ride level is to hook it up to your truck, fully loaded, using a ball mount you think has the proper drop. If the trailer is level, great; if not, adjust accordingly. A good trailer dealer should have extra mounts you can play with.
Inspect your Coupler
The friction from the coupler pressing down and twisting on the ball will wear down a coupler, causing the metal to get thin. Inspect the coupler periodically and if you find even one hairline crack, replace it immediately. Some couplers are bolted on, but some need to be cut off and the new one welded on. Greasing the ball might reduce the wear a little bit, but it’s not worth the mess. If you’re shopping for a trailer and you know you’re going to put tons of miles on it, buy one with a cast tongue rather than stamped metal; they’re thicker and last longer.
Cross the Safety Chains
Crossing the safety chains creates a cradle that the coupler can fall into and will reduce the distance the trailer will swing side to side if it uncouples (shudder!). Crossing chains also keeps them up a little higher so they won’t drag on the road and wear down. Strong chains provide better protection for your trailer and the folks on the road around you. If your chains still drag after crossing them, you can cross them over each other a couple times or just shorten them.
Test Your Emergency Brake
Most states require electric brakes on large trailers, and many require a backup emergency braking system that activates if the trailer is separated from the tow vehicle. The most common type of emergency braking system consists of a cable attached to a key, which fits into a breakaway switch that’s powered by a dedicated battery. The other end of the cable is attached to the truck. In case of separation, the key would be pulled out of the breakaway switch, which would send an electric charge, provided by the battery, to activate the brakes.
Checking the emergency brake system is simple enough. Hook up the trailer, pull the key from the switch, and pull the trailer forward. The wheels shouldn’t roll if the system is working properly. If the brakes don’t engage, you could have a bad switch or faulty wiring, but a dead battery is the usual culprit. Breakaway batteries receive a charge every time you hook up your wiring harness, but they should still be replaced every couple of years.
Use the Proper Size Ball Mount
Not all ball mounts are created equal. Make sure the ball mount you’re using can handle the weight of your trailer and its load. Exact specs can vary, but here are some common ones:
- 1-1/4 x 1-1/4-in. solid steel—1,000 to 3,500 lbs.
- 2 x 2-in. tube steel—up to 7,000 lbs.
- 2 x 2-in. solid steel—up to 16,000 lbs.
Only Use Trailer Tires
Installing car or truck tires on a trailer is a bad idea. Trailer tires (ST for “Special Trailer”) and light truck tires (LT) or other passenger vehicle tires are not built the same. The sidewalls on truck tires have more flex, which improves traction and makes for a more comfortable ride. The sidewalls on trailer tires are stiffer. Stiffer sidewalls increase the amount of weight a tire can handle and reduce the risk that a trailer will sway.
Keep a Good Jack on Hand
Storing a spare trailer tire on board is a no-brainer, but what about the jack? Some trucks have jacks that may not be able to handle a loaded trailer, or they may have a strange configuration that might not work safely on a trailer. Try out your truck jack on your trailer; if it doesn’t work, buy a dedicated trailer jack. The one shown above is a combination jack and jack stand made by Powerbuilt.
Use the Proper Size Ball Shank
The proper size of the ball is not the only thing to consider when buying a ball for your trailer; the size of the ball shank is crucial. The size of the shank determines how much weight the ball can handle. Shank capacities vary, but here are some common specs:
- 3/4-in. shank—up to 3,500 lbs.
- 1-in. shank—up to 7,500 lbs.
- 1-1/4-in. shank—more than 7,500 lbs.
You owe it to the other drivers you’ll be sharing the road with to make sure your trailer is road-worthy every time you take it out. Check the following items before taking to the streets:
- The ball and the coupler are compatible sizes.
- Chains, wiring harness and breakaway cable are all connected.
- Ball mount pin is in place.
- Locking lever is down and pin installed.
- Ball is fastened securely to the ball mount.
- Tongue jack is raised.
- Tires are properly inflated and lug nuts are tight.
- Lights are all working.
- Ramps and/or gates are in place and secure.
- Load is fastened and secure.
- Brakes are working.
Double-Check the Load
Tongue weight is the force that the tongue of the trailer exerts on the back of the truck. Proper tongue weight should be 10 to 15 percent of the combined weight of the trailer and its load. So a 2,000-lb. trailer with a 3,000-lb. load should have a tongue weight of 500 to 750 lbs. The proper way to load a trailer is to keep the bulk of the load over the trailer tires, with a little more weight toward the front.
Too much tongue weight is hard on the truck’s suspension and takes weight off the front tires. This makes the truck unwieldy on curves and reduces stopping distance. Too little tongue weight will cause the trailer to sway back and forth and possibly fishtail out of control.
Unless you have a super-fancy ball mount that has a built-in scale, you’ll have to judge the tongue weight by how much the back of your truck drops down when the trailer is attached. The next time you have a few buddies over, have them climb onto the bumper of your truck. Measure and take note of how much the rear of the truck drops with the added weight.
Even loads that have been properly secured with the appropriate chains or straps can come loose after getting jostled on a bouncy trailer. It’s a good idea to stop after driving a short distance to inspect the load to make sure it’s still secure. And then every time you make a stop, for gas or whatever, check it again. You can’t be too careful.
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