Master Lock 2939AT User Manual
Universal Towbar 2939AT
2939AT Installation Instructions
THIS PRODUCT HAS BEEN DESIGNED TO TOW MOTOR VEHICLES WITH FOUR WHEELS.
IT IS INTENDED FOR LIGHT AND MEDIUM DUTY APPLICATIONS NOT TO EXCEED A MAXIMUM GROSS WEIGHT OF 5,000 POUNDS.
***DO NOT EXCEED VEHICLE MANUFACTURER’S RECOMMENDED TOWING CAPACITY.***
Parts List
QTY DESCRIPTION
1 Coupler Assembly
1 Right Arm Assembly
1 Left Arm Assembly
2 Clevis Bracket
2 Mounting Bracket Assembly
2 Bolt Strap Assembly
2 Backing Strap
4 3/8" Flange Locknut
2 1/2" x 3-1/4" Hex Bolt
Safety Chain
Loop
A
E
C
Mounting
Bracket
Assembly
Cleavis
Bracket
Left Arm
Assembly
D
Coupler
Assembly
We recommend using safety chains when towing (2958AT 60" Safety Chains)
Attach one safety chain to each of the safety chain loops located near the ends of the tow bar arms.
Hardware Kit (Bag)
ITEM QTY DESCRIPTION
B
A 4 1/2" Flange Locknut
B 2 1/2" Hitch Pin
C 2 1/8" Hair Pin
D 4 1/2" x 1-1/2" Hex Bolt
E 4 Reinforcement Plate
1/2" x 3-1/4"
Hex Bolt
Right Arm
Assembly
3/8" Flange
Locknut
Bolt Strap
Assembly
Backing
Strap
Note: Coupler must be adjusted to fit and lock snugly over a 2" ball used for towing.
Never use a pickup or van to tow another vehicle as the light rear end of these vehicles can cause
unsafe towing conditions. When braking, the towed vehicle will push the rear of the towing vehicle. This pushing may
cause the vehicles to jacknife and/or lose control. The air turbulence from passing vehicle can also cause loss of control.
Total weight of the towed vehicle must not exceed 5,000lbs and must not exceed the weight of the towing vehicle. This tow bar is sold less safety
chains. Some states require the use of double safety chains. Use only a Class III 1/4" proof coil chain rated for at least 5,000lbs capacity.
Tow Bar Installation Instructions:
CAUTION: Do not attempt to attach tow bar brackets to any bumper which has a soft urethane outer covering. This type of bumper does not offer a
secure, unyielding attachment point for the tow bar brackets.
1. This tow bar should be attached to bumper components which will give a solid, unyielding attachment point. Bumper bracket mounting bolts may
be used for tow bar attachment if they are spaced properly and have secure frame connections. Some applications may require that special mounting
brackets be built by the installer to give adequate frame attachments and reinforcement.
Check the bumper carefully before attaching only to the bumper face. Most bumpers will not withstand the towing pressure.
2. Center the tow bar on the mounting surface. Spread the arms to at least 24" between the mounting brackets. A spread of 35" to 40" is best for a
secure tow bar alignment. Attach the tow bar mounting brackets to a flat, vertical surface as near the bumper mounting brackets as possible. Drill four
1/2" attachment holes in mounting surface at pre-determined points.
3. Attach the tow bar mounting brackets to their attachment points with 1/2" x 1-1/2" hex bolts (D) and reinforcement plates (E). Place the
reinforcement plates inside the bumper mounting surface. Do not tighten the attachment bolts at this time.
4. Attach the tow bar arms to the installed mounting brackets with the 1/2" hitch pins (B) and hair pins (C) supplied with the tow bar.
5. Tighten the four 1/2" mounting bracket attachment bolts to 75ft-lb torque.
NOTE: This tow bar is to be installed on a vehicle with a loaded gross weight under 5,000lbs.
NOTE: It is the responsibility of the installer and consumer to identify and use a safe and secure attachment for the tow brackets.
PERIODICALLY CHECK THIS TOWBAR TO ENSURE THAT ALL FASTENERS ARE TIGHT AND THAT ALL STRUCTURAL COMPONENTS ARE SOUND.
FOR TECHNICAL ASSISTANCE CALL 1-800-344-3230 8am-5pm EST Monday-Friday
Hook Up Instructions:
1. Attach the tow bar to its mounting brackets on the towed vehicle using the 1/2" hitch pins and hairpins supplied in kit.
2. Attach the coupler of the tow bar to a 2" ball with a weight capacity equal to or exceeding the weight of the towed vehicle. Adjust the coupler to fit
the 2" ball so that it fits snugly over the ball. The hitch to which the 2" ball is attached must have a load capacity that is equal to, or exceeds the weight
of the towed vehicle. Read and follow the operation instructions attached to the coupler.
3. Center the coupler on the tow bar arms and tighten the 3/8" bolts to 30ft-lb torque. Be sure that the coupler underjaw is adjusted to lock snugly
over the 2" ball.
4. This tow bar is sold less safety chains. Some states require that two safety chains be used with a tow bar. Use only a Class III 1/4" proof coil safety
chain with this tow bar. Attach the safety chains to the towed vehicle frame. Cross the safety chains under the coupler at the front of the tow bar and
attach securely to the towing vehicle. Safety chains should be run through the chain loops on the tow bar arms to prevent them from dragging on the
ground.
5. Connect an adequate wiring harness between the two vehicles so that the stop, turn and running lights operate on the towed vehicle in conjunction
with the lights on the towed vehicle.
Towing and Precautions:
Steering wheel of towed vehicle must be unlocked.
Vehicles with automatic transmissions must utilize a fluid pressure system.
If towed vehicle is rear wheel drive, the driveshaft may be removed before towing.
Place towed vehicle in neutral and check that parking brake is not applied.
Warning:
Stopping distances will increase, adjust your driving accordingly.
Do not back-up while vehicle is attached. Backing up while vehicle is attached will produce excessive forces to the towbar and to the vehicle in tow.
Damage will occur.
Large forces will occur while starting forward if wheels are turned. This practice effectively “drags” the front of the vehicle being towed until the wheels
of the towed vehicle themselves are turned in the direction of movement.
Consult Your Vehicle Owner’s Manual for Towing Limitations.
Safety Tips
NO PASSENGERS IN TRAILERS! People should never ride in trailers while towing, under any circumstances.
TRAILER LOADING Proper loading helps prevent trailer sway. Position heavy objects on the trailer floor ahead of the axle. Balance the load
side-to-side. Secure load to prevent shifting. Tongue weight should be 10-15% of gross weight for most trailers. Too low a percentage of tongue
weigh can cause sway. NEVER load the trailer rear-heavy. LOAD THE TRAILER HEAVIER IN FRONT.
DRIVING ON THE ROAD The additional weight of a trailer affects acceleration, braking and handling. Allow extra time for passing, stopping, and
changing lanes. Severe bumps can cause damage to your towing vehicle, hitch, and trailer. Drive slower on rough roads.
STOP AND MAKE A THOROUGH INSPECTION IF ANY PART OF YOUR TOWING VEHICLE SYSTEM HITS THE ROAD. CORRECT ANY PROBLEMS AND
REPLACE ANY DAMAGED PARTS BEFORE RESUMING TRAVEL.
CHECK FOR EXCESSIVE SWAY AND CAUSE
Excessive trailer sway can lead to loss of control. Sway motion should recover quickly. Sway tends to be worse on downgrades. Start slowly, and
increase your speed in gradual steps. If sway does occur, redistribute your trailer load. Repeat until the trailer is stable at highway speed.
IF TRAILER SUDDENLY STARTS TO SWAY
Turbulence from another vehicle, a wind gust, or a downgrade can cause a sudden sway, along with a shift of the trailer’s load or a trailer tire blowout.
IF THE TRAILER SWAYS, IT IS THE DRIVER’S RESPONSIBILITY TO ASSESS THE SITUATION AND TAKE APPROPRIATE ACTION. Below are
suggestions that may apply, depending on conditions:
DO •Reduceyourvehiclespeedgradually.
•Holdthesteeringwheelassteadyaspossible.
•Ifyourtrailerhaselectricbrakes,applythetrailerbrakesalone,withoutusingthetowvehicle’sbrakes.
DON’T •Don’tdepressyourbrakepedalhardunlessabsolutelynecessary.A“jackknife”canresult.
•Don’ttrytosteeroutoftheswaycondition.Suddenorviolentsteeringmaymakethesituationworse.
•Don’tincreasespeed.Swayincreasesthefasteryougo.
• Don’t continue towing a trailer that tends to sway. You may lose control during an emergency maneuver,
or if the conditions listed above occur.
DANGER
DO NOT MODIFY PRODUCT IN ANY WAY. TOWING VEHICLE MUST BE IN GOOD DRIVING CONDITION. USE ONLY FOR TRAILER TOWING
AND/OR ATTACHMENT OF ACCESSORIES. DO NOT EXTEND ORIGINAL STRUCTURE. DO NOT TOW ONE TRAILER BEHIND ANOTHER, THIS MAY
CAUSE LOSS OF CONTROL. FAILURE TO HEED WARNINGS AND FOLLOW THESE INSTRUCTIONS MAY RESULT IN A SERIOUS PERSONAL INJURY
OR DEATH, VEHICLE CRASH, AND/OR PROPERTY DAMAGE.
BE SURE TO NOT OVERLOAD ANY COMPONENT OF YOUR TOWING SYSTEM
w w w . masterlock. com
Master Lock Company LLC, Milwaukee, WI 53154 U.S.A. | 800-308-9244
Master Lock Canada, Oakville, Ontario L6H 5S7 Canada | 800-227-9599
© 2008 Master Lock Company | All Rights Reserved
83175
TOWING EQUIPMENT
TRAILER HITCHES, RECEIVERS, AND BALL MOUNTS Select these products by taking into account their gross trailer weight and tongue weight ratings.
Match the products according to the anticipated use. Use only those products designed for your vehicle.
HITCH BALLS Select the proper hitch ball by gross trailer weight rating, mounting platform thickness, hole size, and coupler socket size. Do not
interchange one class of hitch ball with another class of coupler. Platform must be at least 3/8" thick. Mounting hole must not exceed threaded shank
diameter by more than 1/16". Use lock washer. Tighten per instructions, and when tightened, shank must extend beyond bottom of nut. Gross trailer
weight rating and ball diameter are marked on all hitch balls.
COUPLERS The coupler opening should be smooth, free of dirt, and lightly lubricated. Tighten or adjust per manufacturer’s instructions. Use recommended class type.
SAFETY CHAINS AND CABLES Use safety chains or cables EVERY TIME YOU TOW. Chains or cables should cross under the coupler. This is done to form
a cradle for the trailer tongue in the event the ball and coupler separate. Install to the hitch or tow vehicle so they can’t bounce loose. Leave only enough
slack to permit full turning of the vehicle. Having too much slack in the chains may prevent chains from maintaining control if other connections fail.
Chains or cables shouldn’t drag on the road to avoid chain failure.
TRAILER LIGHTS, TURN SIGNALS, ELECTRIC BRAKES, AND BREAK AWAY SWITCH CONNECTIONS Connect these safety-critical items EVERY TIME YOU
TOW, no matter how short the trip. Check operations including electric brake manual control, before getting on the road.
SWAY CONTROLS Sway controls lessen the effects of sudden maneuvers, wind and buffeting from other vehicles. They’re recommended for trailers with large
surface areas. Adjustable friction models can help control trailers with low tongue weight. Recommended tongue weight should be 10% of gross trailer weight.
OTHER EQUIPMENT AIR SPRINGS, AIR SHOCKS, or HELPER SPRINGS are used for some towing applications. A TRANSMISSION COOLER may be
necessary for heavy duty towing. Some states require TOWING MIRRORS on both sides of the vehicle.
TIRE INFLATION Check often. Follow tow vehicle and trailer manufacturers’ recommendations. Improper tire inflation can cause uncontrollable trailer sway.
CHECK YOUR EQUIPMENT Check hitch ball, coupler, safety chains/cables, retaining pins and clips, and all other connectors EVERY TIME YOU TOW.
Check again at stops.
Contains Important Information About Towing
TOWING EQUIPMENT OWNERS: Make sure all users of your equipment read and understand the information below before using. Keep this
information for future reference. This information will help you properly select, use, and maintain your towing equipment. Refer to the owner’s
manuals for your tow vehicle, trailer, and other parts of your towing system. Learn the capabilities and limitations of each component. GROSS
TRAILER WEIGHT and TONGUE WEIGHT are two of the most important items to consider. THESE WEIGHTS MUST NEVER EXCEED THE
LOWEST RATING OF ANY PART OF YOUR TOWING SYSTEM. GROSS TRAILER WEIGHT is the weight of the trailer plus all cargo. Measure
GROSS TRAILER WEIGHT by putting the fully loaded trailer on a vehicle scale (Fig. 1). TONGUE WEIGHT is the downward force exerted on the
ball by the trailer coupler. Measure TONGUE WEIGHT with the fully loaded trailer on a level surface. The coupler must be at its normal towing
height. Use a commercial scale as shown for heavy tongue weights (Fig. 2).
This product complies with regulation V-5, C.S.A. Standard D-264 and safety requirements for connecting devices and towing systems of the state of New York.
THREE YEAR LIMITED WARRANTY
Master Lock Company warrants this hitch against defects in material and workmanship under normal recreational use and service, ordinary wear and tear excepted, for three years from the
date of purchase of the original consumer purchaser. Master Lock Company will replace FREE OF CHARGE any part which proves defective in material or workmanship when returned to factory,
TRANSPORTATION CHARGES PREPAID, at the address below. THIS WARRANTY IS LIMITED TO DEFECTIVE PARTS REPLACEMENT ONLY. LABOR CHARGES AND/OR DAMAGE INCURRED IN
INSTALLATION OR REPLACEMENT AS WELL AS INCIDENTAL AND CONSEQUENTIAL DAMAGES CONNECTED THEREWITH ARE EXCLUDED. Some states do not allow the exclusion or limitation
of incidental or consequential damages, so the above limitation or exclusion may not apply to you. Any damage to the Hitch, Custom Hitch receiver or Sway Control as a result of misuse, abuse,
neglect, accident, improper installation, or any use violative of instructions furnished by us, WILL VOID THE WARRANTY. This warranty gives you specific legal rights, and you may also have
other rights which vary from state to state. In the event of a problem with warranty service or performance, you may be able to go to a small claims court, a state court, or a federal district court.
Master Lock Company warrants this product to be free of defects in material and workmanship at the time of retail purchase by the original purchaser.
If the product is found to be defective, Master Lock Company may repair or replace the product, at their option, when the product is returned, prepaid,
with proof of purchase. Alteration to, misuse of, or improper installation of this product voids the warranty. Master Lock Company’s liability is limited
to repair or replacement of products found to be defective, and specifically excludes liability for incidental or consequential loss or damage.
Master Lock Company Return Goods
c/o All In One Warehouse
2050 N. Smokey Lane, Suite B
Nogales, AZ 85621
Fig. 1: HOW TO MEASURE GROSS TRAILER WEIGHT
PUT FULLY LOADED TRAILER ON VEHICLE SCALE
Fig. 2: HOW TO MEASURE TONGUE WEIGHT
SET TONGUE OF FULLY LOADED TRAILER ON VEHICLE SCALE
Contact Customer Care at 1-800-308-9244 for return authorization.
05/08
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