GUIDELINES FOR TOWING A TRAILER
I. Because a tow vehicle and a trailer form an articulated (hinged) vehicle, weight
considerations are very important to safe towing. The tow vehicle must be a proper
match for the trailer. To use a Transportation Service vehicle as a tow vehicle the
towing specification worksheet must be filled out and submitted with the Form 1 a
week prior to the trip.
II. The ball and coupler hitch is used on a wide variety of tow vehicle combinations.
This hitch consists simply of a ball attached to the rear of a tow vehicle and a coupler
(socket) at the tip of a tongue or A-frame attached to the front of the trailer. This hitch is
commonly used on recreational trailers.
A load distributing hitch is used for heavier models such as utility trailers, boat trailers,
and travel trailers. These load distributing hitches use special equipment to distribute the
tongue load to all axles of the tow vehicle and trailer to help stabilize the tow vehicle.
Here are some terms you should know when discussing hitch adjustment and in
evaluating hitch performance:
* Receiver: Hitch platform fitted to the tow vehicle.
* Ball mount: A removable steel component that fits into the receiver. The ball and
spring bars (only on load distributing hitches) are attached to it.
* Sway Control: A device designed to lessen the pivoting motion between tow vehicle
and trailer when a ball-type hitch is used.
* Coupler: A ball socket at the front of the trailer A-frame that receives the hitch ball.
* Spring Bars: Load-leveling bars used to distribute hitch weight among all axles of
tow vehicle and trailer in a load distributing ball-type hitch.
III. Weight definitions:
* Base Curb Weight - Weight of the vehicle and trailer not including cargo or any
optional equipment.
* Cargo Weight - Includes cargo, passengers and optional equipment. When towing,
trailer tongue weight is also part of the Cargo Weight.
* Gross Axle Weight (GAW) - The total weight placed on each axle (front and rear).
To determine the Gross Axle Weights for your vehicle and trailer combination, take your
loaded vehicle and trailer to a scale. With the trailer attached, place the front wheels of
the vehicle on the scale to get the front GAW. To get the rear GAW, weigh the towing
vehicle with trailer attached, but with just the four wheels of the vehicle on the scale.
You get the rear GAW by subtracting the front GAW from that amount. In the absence of
a scale, calculate the Front Gross Axle Weight by adding the Front Axle Curb Weight to
the Cargo Weight (including passengers) assigned to the front 1/2 of the van. Calculate
the Rear Gross Axle Weight by adding the Rear Axle Curb Weight to the Cargo Weight
(including passengers) assigned to the rear 1/2 of the van and the Tongue Weight of the
trailer.
* Gross Axle Weight Rating (GAWR) - The total weight each axle (front and rear) is
capable of carrying. These numbers are shown on the Safety Compliance Certification
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Label located inside the driver side door frame. The total load on each axle (GAW) must
never exceed its GAWR.
* Gross Combination Weight (GCW) - The weight of the loaded vehicle (GVW) plus
the weight of the fully loaded trailer. It is the actual weight obtained when the vehicle
and trailer are weighed together on a scale.
* Gross Combination Weight Rating (GCWR) - The maximum allowable weight of
the towing vehicle and the loaded trailer (including all cargo) that the power train can
handle without risking costly damage. The measured GCW must never exceed the
GCWR. (Important: The towing vehicle’s brake system is rated for safe operation at the
GVWR -- not GCWR. Separate functional brake systems should be used for safe control
of towed vehicles and for trailer weighing more than 3,000 lbs. when loaded).
* Gross Vehicle Weight (GVW) - Base Curb Weight plus actual Cargo Weight. It is
the actual weight that is obtained when the fully loaded vehicle is driven onto a scale.
* Gross Vehicle Weight Rating (GVWR) - The maximum allowable weight of the fully
loaded vehicle (Base Curb Weight plus options plus cargo). The vehicle’s measured
GVW must never exceed the GVWR. The GVWR along with other maximum safe
vehicle weights, as well as tire, rim size and inflation pressure are shown on the vehicle’s
Safety Compliance Certification Label.
* Gross Trailer Weight - Is the highest possible weight of a fully loaded trailer the
vehicle can tow. It assumes a towing vehicle with mandatory options, no cargo and the
driver only (150 lbs.). The weight of additional optional equipment, cargo and hitch must
be deducted from this weight.
* Payload - Maximum allowable weight of cargo that the vehicle is designed to carry.
It is Gross Vehicle Weight Rating minus the Base Curb Weight.
IV. Safety:
Perform a safety inspection before each trip: Make sure that the pin securing the ball
mount to the receiver is intact, the hitch coupler is secured, spring bar hinges are tight
with the safety clips in place (load equalizer or weight distributing hitches), safety chains
are properly attached and the electrical plug is properly installed.
Practice trailer backing: Backing a trailer into tight places is easier than it looks, but it
does take some practice. It’s best to practice in a parking lot and in a vehicle that allows
you to see the trailer through the rear window. Vans, trucks and campers that have
obstructed rear views require more practice and the use of side mirrors. In either case, be
patient, and make steering adjustments slowly and a little at a time.
Watch your tongue weight: How a trailer handles down the road depends upon tongue
weight. Too much weight will cause the rear of the trailer to sway and make the tow
vehicle difficult to control. The tongue weight should not exceed 200 pounds for trailer
up to 2,000 pounds. Tongue weight for trailers over 2,000 pounds should be 10 to 15%
of the trailer’s loaded weight.
Take care of tires: It’s wise to periodically check tires for wear, cuts or other damage
and replace as needed. Above all, maintain the tire pressure recommended by the
manufacturer, located on the tire sidewall. Improperly inflated tires will cause them to
wear out quicker and reduces fuel mileage.
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Keep bearings greased: Wheel bearings are the heart of trailers. They need to remain
airtight and packed with fresh grease. Poorly greased bearings will overheat and
deteriorate, creating serious problems if they fail. They should be inspected and repacked
at least once a year, depending upon the amount of use. Lay your hand on your wheel
hubs after traveling. If they feel unusually warm, you may have a problem. But why
wait? Routine maintenance is good prevention.
Go wide on turns: Be careful making sharp turns or sudden moves when trailering. The
trailer tends to cut corners more sharply than the tow vehicle which can be dangerous
when cutting corners close to curbs, other vehicles and road-side obstructions. Striking
solid objects at an angle can cause tire damage, and more importantly, cause you to lose
control momentarily.
Be a weight watcher: When loading, balance the cargo with 60 percent of the weight
near the front.
Secure the trailer: Keep the safety chains provided on most trailers fastened securely to
the tow vehicle in case the hitch fails. Cross the chains under the trailer tongue and allow
slack for turning. For additional security, padlock the trailer hitch to the tow vehicle.
That will also prevent someone from stealing the trailer while you’re away from the
vehicle.
Keep the lights working: The trailer’s electrical components are subjected to a great
deal of adverse conditions, so check them periodically. Ask someone to step behind the
trailer to make sure the tail lights, brake lights and turn signals are working properly. If
signals are dim, perhaps there is a bad connection or you need a more powerful flasher
unit on the tow vehicle. An occasional shot of WD-40 into the pig tail wiring connector
will reduce corrosion.
Make sure your vehicle has towing power: Just because a vehicle has the power to pull
a loaded trailer down the road doesn’t mean it has the guts to haul it up steep hills, or that
brakes are capable of holding it on a steep incline. Follow manufacturers’ towing
guidelines and never exceed tow limits. Too much trailer weight can cause an accident,
or pull the tow vehicle down a steep incline.
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