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Safe Towing - Tow, Chase, Haul!

Posted in How To on March 1, 2009
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If you're like us, you sometimes need to tow a trailer -- be it for a boat, off-road toys, or just plain cargo of some sort. It seems simple enough to latch on the wheeled appendage behind your tow vehicle and hit the road. However, a little knowledge of the equipment needed, towing practices, and safety procedures can serve you well to ensure your trip is successful.

The first thing you'll want to consider when planning to tow is that the vehicle you plan to tow with has sufficient capacity to pull, turn and stop the trailer you're attaching to it. As a start, consult your owner's manual where you'll find the recommended maximum tow load weight. It will often list both gross trailer weight (weight of trailer plus cargo weight) and tongue weight that can be placed on the bumper or frame mounted hitch.

Choosing A Hitch
Most step bumpers will accept a tow ball but are often only rated as a Class I hitch. This is fine for towing a light trailer with some off-road toys. But, if you plan to tow a decent sized boat or a good-sized four-wheeled vehicle, you'll want to upgrade to a beefier frame mounted hitch. The table below details the trailer class ratings:

Trailer
Class
Max. Gross
Trailer Weight
Max. Tongue
Weight
I 2000 lbs. {{{200}}} lbs.
II 3500 lbs. 350 lbs.
III {{{5000}}} lbs. 500 lbs.
IV 12,000 lbs. 1200 lbs.

When choosing a trailer hitch for your tow vehicle, choose one that exceeds the expected load of your trailer, but does not exceed the tow rating of your tow vehicle. Recommended tongue weight is usually 10 percent of the loaded trailer weight.

Class I trailers typically mate to a 1 7/8-inch trailer ball, while Class II and III trailers match up to a 2-inch ball. Class IV trailers usually require the even larger 2 5/16-inch size. Never mount a trailer to a vehicle with a smaller sized ball as this will both damage the coupler and cause a safety risk.

Also, consider the wheelbase of the tow vehicle and of the trailer behind. We're amazed when we see rigs such as a Jeep TJ towing a 24-foot trailered boat behind it. The sheer trailer length of that combination can make steering and stopping very tricky behind such a short wheelbase vehicle. Terrain in your area may also dictate what tow/trailer combination is reasonable. Pulling up and down hills safely takes greater engine power and substantial braking to keep tow vehicle and loads safely under control.

Capacity & Braking
As trailer weights and loads rise so do the needs for greater trailer strength and braking abilities. The trailer frame structure must be beefier and rolling hardware may need to grow to a two-axle or three-axle setup. Both of these upgrades further increase the weight of the trailer you're pulling.

Most tandem axle and larger trailers add electric actuated brakes or surge braking systems that utilize a hitch sensing device to actuate a brake master cylinder to apply the trailer brakes when the tow vehicle slows or stops.

Maintenance & Mishaps
Trailers may seem simple and many are. However, they're often abused and neglected, and doing so can leave you with a broken down trailer or a damaged vehicle. We spoke with Eric Schouten at Lewis Hitches in Chandler, Arizona, about the kinds of mistakes and troubles they see in regards to the trailers they service and rebuild for customers.

With his everyday view of numerous trailers, he's found that neglected bearing service can lead to bearing failure and that common scene we see of a trailer stopped on the side of the highway. Bearings that haven't been greased from time to time can seize and fail, often heating up and ruining the axle spindle or other nearby components as well.

Eric also mentioned the most common causes for trailer accidents. These conditions may not cause severe damage or injury but there's always the possibility. Common mishaps are: forgetting to latch the coupler, using the wrong ball size, or forgetting to raise the trailer jack, resulting in a bent jack frame at a minimum.

Securing Your Towed Rig
Any time you load a vehicle on a trailer, be it flat bed or enclosed box trailer, you'll need to secure it to the deck to prevent it from moving about or causing any weight shift on the trailer. Most days of trailering will go well and you'll get to and from your destination without incident. However, consider a condition where you're forced to brake quickly, perform an unexpected evasive maneuver, or make a sharp turn at a higher than prudent speed. That's when you'll want your trailered rig secure and stable on the deck, and contributing no other unwanted movement during the event.

We gained some further knowledge on proper securing techniques from Colin McLemore of Mac's Custom Tie-Downs, a specialty company that provides high quality tie-down systems for trailers and truck beds. He commented that the method of vehicle tie-down is often much more an intuitive decision on the part of the vehicle owner, rather than a decision based on safety knowledge.

Colin urges that the correct method of securing a vehicle is from the axles and not the chassis or body. There are two significant reasons for this. First, when a chain or strap is used on the suspended body it can go slack and possibly disconnect when the trailer hits a bump and the towed vehicle suspension is compressed. Second, this action causes impact loads on the chain or strap. This impact can damage strap rachet mechanisms and fracture strap hooks or attachment points.

Vehicles should be secured with a four-point system that captures the axles, lower control arms, or the tires. In other words four separate straps or chains (your preference) should be used. With two used on each end of the vehicle, you have a backup should one of them fail. If you have a vehicle with a tall, soft suspension then consider supplementing the four-point system with several additional straps to compress the suspension a bit and stabilize the body lean and bounce.

Choosing the right trailer, hitch, braking, and other safety gear will help ensure your precious cargo makes it to your destination without incident. With some regular preventive care, your trailer should work reliably and keep you from being stranded by the roadside. Most of all, keep your trailering safe as an out-of-control trailer careening down the highway is a sure way to ruin the rest of your day, at a minimum.

This is a common Class III frame mounted hitch that would fit a -ton pickup. It provides a receiver and accepts a slide-in ball mount that supports the ball. This type of hitch is secured to the inside of the frame rails of a truck frame using a number of bolts. Such a hitch offers greater load capacity than a simple ball mounted on a step bumper. Photo courtesy of Draw-Tite.

This display shows a Valley Industries Husky weight distribution hitch. Such a hitch can be used when pulling heavy loads and uses an attachment that slides into the receiver and redistributes the weight on the tongue. Two spring bars (below) on the hitch are used to apply leverage back onto the tow vehicle. This setup helps to redistribute weight over the entire length of the tow vehicle and trailer to provide improved towing stability.

On every manufactured trailer you'll find a tire and loading decal that specifies the recommended tire size, tire inflation pressure, and the maximum load rating for the trailer. This information is useful to prevent overloading of the trailer, which is one of the primary causes of tire and trailer axle failures.

On every manufactured trailer you'll find a tire and loading decal that specifies the recommended tire size, tire inflation pressure, and the maximum load rating for the trailer. This information is useful to prevent overloading of the trailer, which is one of the primary causes of tire and trailer axle failures.

This is a clamshell style or Bulldog coupler. It has a forged ball receptacle that is hinged and locks in place over the hitch ball with the use of a sliding circular collar. These couplers offer the advantages of long wear and a more secure coupling due to the full spherical ball capture mechanism. This coupler is attached to a hitch that has a ball height adjustment. It's also important to reasonably match the trailer tongue height to the tow vehicle hitch height to keep the trailer fairly level during towing. This will balance the trailer better for improved handling and keep one end or the other from dragging on the ground when you go over uneven terrain.

There has been various trailer connectors, spanning from four- to seven-connector pins. The basic four-way type can provide running lights, braking, and turn signals. Additional pins in larger connectors can provide a signal for electric braking, a 12-volt power source, or other functions. Recent model trucks come with the latest seven-way round connector as shown here.

The most common connector types in use are the flat four-pin, the round six-pin, and the latest seven-pin style. There is also a five-pin type as well.

If there is a mismatch between the tow rig connector and the trailer connector, you can often mate the two with an adapter that is commonly available at auto suppliers. You'll always want the tow vehicle connector to have a greater number of electrical pins than the trailer connector in order to retain all the electrical features of the trailer.

This is an example of a hydraulic surge brake actuator. These are commonly used on boat trailers. This type of system uses no electrical braking information from the tow vehicle. The coupler senses an inertial pressure difference or "push" between the tow vehicle and the trailer when the tow vehicle starts to slow down. When this occurs, a rod inside this coupler box presses on a brake master cylinder to apply braking pressure to disc or drum brakes at the trailer wheels. Greater or lesser braking is applied automatically based on the slowing rate of the tow vehicle.

Here's the view of the rear of a surge brake actuator. You can see the brake master cylinder inside the housing. One often overlooked maintenance item is that of checking the fluid level in these actuators. Also, there is typically a braking disable device (electrically actuated or manually inserted pin) that can be applied if the trailer must be backed up a slope, a condition that would normally apply the brakes through the surge actuator.

This is an unmounted electric drum brake unit with backing plate. Its back flange mounts to a trailer flange and a drum is placed over the brake shoes. When voltage is applied to the magnetic actuator (arrow) it pushes outward on the shoe(s) to engage the braking function.

Another trailer safety device found on trailers with electric brakes is a breakaway activation system. This consists of a small cable that connects between the tow vehicle and the trailer. Should the two become disconnected, the cable pulls a pin on the breakaway switch (left arrow) and activates the electric brakes. A small battery mounted in a plastic box (right arrow) on the trailer tongue provides the needed power to apply the brakes on a runaway trailer and bring it to a halt.

In the case of a trailer that has electric brakes or a hydraulic surge brake unit, the breakaway cables and/or chains must be connected properly. If the connection length is incorrect, it may be possible for the brakes to become activated during sharp turning or other normal towing situation. If this happens, the brakes may apply without the driver's knowledge. If towing continues, the brake assembly can overheat and destroy axle components.

When using electric brakes, a small controller is installed in the cab of the tow vehicle and wired into the brake lighting. When the brakes are applied, voltage is transmitted to the trailer to engage the brakes. A manual sliding switch on the controller also allows you to apply only the trailer brakes with tow vehicle brake activation. There are two main types of brake controllers: proportional and time delayed. Each has its pros and cons, depending on the specific tow situation.

While this trailer deck is large enough to carry a full-size car or truck, its wheels, tires, and axles are not stout enough for such a load. A common load rating for an axle such as this 3,500 pounds. Remember that the load includes the weight of the trailer plus the weight of cargo. Trailers such as these are more appropriate for lighter vehicles such as UTVs, quads, and dirt bikes.

When choosing a trailer to haul a large vehicle such as a sandrail, Jeep, or truck there are several styles available with varying load ratings. Deck surfaces can be open, or filled with aluminum or steel sheet, or with wood planks. Metal decks typically last longer, but a wood deck is a more tolerable work surface in the hot sun. Trailer rail styles also vary, and may be added to increase the chassis rigidity. Note also that the fore/aft axle positioning can vary and is important to consider with respect to the loaded vehicle weight and positioning to achieve good balance and proper tongue weight on the tow vehicle.

Submersing your trailer in the lake? Water contamination is probably the number one enemy of axle bearings. The guys at Lewis Hitches mentioned that what often kills the bearings is not as much the water egress from weekend to weekend, but rather the time the water sits inside the hubs over the off-season and starts the corrosion process inside the hub. Hubs that offer external grease zerks can help prolong bearing life, however pumping too much grease into the hub can push it past the seal and contaminate the brake shoes or pads. Even with this type of hub, the bearing assemblies should be torn down and freshly greased at some service interval based on mileage and use.

Trailer axle failures are not uncommon. You'll spot the broken trailers along the highway with missing or shredded tires, damaged wheels, or more serious axle or brake failures. The large majority of these can almost certainly be attributed to poor axle maintenance and/or overloading of the trailer.

Trailer tires should also be chosen for their load rating. It is certainly possible to install passenger car tires on a heavy duty trailer and stay within the load ratings. However, there are tires designed specifically for trailer use and designated as `ST' type. These tires typically have stiffer sidewalls to reduce sway and tread designs meant to help a narrower tire run cooler and last longer in a trailer application where the tires are neither driven nor steered. `ST' rated tires have a maximum speed rating of 65 mph.

Trailer tires should always be inflated to the maximum pressure printed on the tire sidewall. The most common cause of trailer tire blowout is heat due to under-inflation. A small leak that causes the tire to deflate can go undetected much more easily on a trailer than on the car or truck you're driving. If you blow a tire on a tandem axle trailer, it is often a good idea to also replace the second tire on the same side of the trailer as it was probably overloaded when the first tire blew.

Small trailer tires can work fine for very lightweight trailers and loads. However, their smaller bearings will be more sensitive to overloading and their small diameter means they turn considerably faster than a full-size tire. Ensure that the hubs are well lubed with a quality grease.

Properly securing your precious cargo is just as important as the trailer connection to your tow vehicle. Consider that the trailer will bounce and move about, and transfers that action through your tie-down straps or chains. When slack occurs, hooks can come loose and exit their attachment points, possibly yielding ugly results. Ideally, all straps should use latching hook ends that remain fully captive even under slack conditions.

There is much debate as to whether vehicles should be secured to trailers by the axles or by the chassis. Strapping or chaining a vehicle to the trailer at the axles keeps it clamped tightly to the deck with only the vehicle tires as a "squish" point. The body is left to move about freely on top of its suspension. Straps should be run in a straight line to the end attachment point on the trailer, but not run over or around any structure such as has been done at the end of the trailer shown here. Synthetic straps offer great tensile strength but can tear when abraded against a surface.

Strapping a vehicle down by its chassis allows you to compress some of the suspension travel, and thus, reduce the amount that the body sways on top of the trailer. However, trucks typically have a good bit of suspension travel. When the trailer hits a bump in the road and compresses the suspension on the trailered rig, the chains or straps may go slack if hooked to the frame. The best method is to strap the axles and supplement with chassis straps if needed. Additionally, it's usually best to trailer a vehicle with it in low gear (manual) or in park with the E brake set.

Here's an example where a lightweight moon buggy was strapped down on a fifth wheel trailer using racheting straps. The straps were secured around the front and rear suspension links next to the frame link mounts. However, the straps are routed over the steel corner of the trailer, causing a point of abrasion on the strap. If such routing is necessary, protect the strap with a rag, piece of carpet, or cardboard placed between the strap and the trailer corner. As a side note, never use a winch cable as a primary means of securing a vehicle to a trailer. The tension placed on the cable as the vehicle is trailered can shock load and damage the internal planetary winch gears.

Sources

Mac's Custom Tie-Downs
Sagle, ID 83860
800-666-1586
www.macscustomtiedowns.com

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