Coupler
Trailer Hitch Ball Mount
Trailer Ball
Safety Chains T-Connector
Scan for live Understanding digital version towing Always review the vehicle owner's manual prior to purchasing It is also important to be aware of the different laws and a towing system. The owner's manual has helpful information restrictions between states. The State Patrol is a good about the vehicle's capabilities, capacities and limitations. resource for this information.
Gross Trailer Weight (GTW) Weight Carrying Capacity (WC) The gross trailer weight is the weight of the trailer and cargo. The measure of the total weight a trailer hitch can safely pull Measure this by putting the fully loaded trailer on a vehicle scale. without adding a weight distribution system. Never exceed the weight capacity ratings of the tow vehicle or the trailer Boat + Trailer + Cooler + Fishing Gear = Gross Trailer Weight hitch, whichever is lower.
8 • UNDERSTANDING TOWING • curtmfg.com • 1.877.curtmfg Weight Distributing Capacity (WD) Tongue Weight (TW) The measure of the total weight a trailer hitch can safely pull The downward force that is exerted on the trailer ball by the with a weight distribution system installed. The use of a weight coupler. The tongue weight will vary depending on where distribution hitch and sway control balances the weight of the the load is positioned in relationship to the trailer axle(s). cargo throughout the trailer, allowing for better steering, braking To measure the tongue weight, use either a commercial and level towing. See page 219 for weight distribution products. scale or a bathroom scale with the coupler at towing height. When using a bathroom scale, use the method shown below and multiply the bathroom scale reading by three.
To Trailer
Without weight distribution
2' 1'
Pipes Bathroom Scale Brick With weight distribution
Sway Control Safety Chains A device used to reduce the lateral movements of trailers, which Safety chains are required by law and should be crossed are caused by the wind. These may be used with or without a under the tongue of the trailer so that the tongue will not drop weight distribution system. Do not use this on a trailer hitch with to the road if it becomes separated from the hitch. Always an 1 1/4" x 1 1/4" receiver tube opening or on trailers with surge leave enough slack so the vehicle can safely turn. Never allow brakes. See page 224 for our sway control products. the safety chains to drag on the ground and never attach the chains to the bumper. CURT offers safety chains in a variety Trailer Hitch of capacities to meet your customer's towing needs.
Sway Control Trailer Each safety chain or safety cable must equal or exceed the gross trailer weight rating of the trailer. See page 241 custom Weight Distribution chain, or page 240 for standard packaged safety chain. Trailer Balls The object that connects the trailer hitch and the trailer. There are many factors that determine the correct trailer ball: • Most important is the trailer ball's gross trailer weight rating • The mounting platform hole diameter must not be more than 1/16" larger than the threaded trailer ball shank Before towing, check the nut and lock washer to make sure they are fastened securely.
Note: The mounting platform must be at least 3/8" thick. Proper safety chain routing See page 156 for our complete trailer ball line. crosses under the coupler
A: Ball diameter B: Shank length C: Shank diameter D: Rise
1.877.curtmfg • curtmfg.com • UNDERSTANDING TOWING • 9 Ball Mounts Couplers The ball mount is placed inside the receiver tube opening The component that is placed over the trailer ball to connect of the trailer hitch, which is mounted to the vehicle. Make the vehicle to the trailer. The trailer's coupler size determines sure a lock or a pin & clip is properly securing the ball mount which trailer ball to use - the two sizes must be identical. to the trailer hitch before towing. See page 138 for our Always make certain the coupler handle is securely fastened. selection of ball mounts. Be sure the coupler is properly adjusted to the trailer ball. See page 230 for our selection of couplers.
Pintle Mounts and Hooks Gooseneck Hitches Commonly used in the agriculture and construction Commonly used to haul livestock, horse trailers or heavy industries to tow large equipment. CURT carries a wide work trailers; the CURT gooseneck hitch line offers several variety of pintle hooks and combination ball / pintle hooks styles to fit the towing application. The under-bed hitches to help tow the heaviest of loads. See page 226 for our and installation kits allow full use of the truck bed. selection of pintles and mounts. See page 198 for our complete line of gooseneck hitches.
Towing Accessories Hitch Pins and Locks CURT's accessory line provides a wide variety of protection Secures all ball mounts and other hitch-mounted accessories for the vehicle's towing system while a trailer is not being to trailer hitches. Hitch locks have the added benefit of theft towed. See page 166 for our selection of towing accessories. deterrence. See page 162 for towing security products.
Bumper Hitches Bumper Styles These hitch applications are only used for light weight towing, including bike racks and cargo carriers. Towing weights should not exceed the vehicle's bumper gross Standard Step towing weight rating; hitch capacities are limited to bumper capacities. Do not use a weight distribution hitch with these products. See page 36 for our bumper hitches. Tube Roll Pan (flush with tailgate)
Drop
Deep Drop I Cowboy
Hitch Box Bumper Hitch RV Bumper Hitch 5,000 lbs. GTW 4,000 lbs. GTW 3,500 lbs. GTW 500 lbs. TW 400 lbs. TW 350 lbs. TW
10 • UNDERSTANDING TOWING • curtmfg.com • 1.877.curtmfg Trailer Hitches Attached to the vehicle, the trailer hitch is the primary device weight of the trailer being pulled. Do not exceed the lowest that allows a vehicle to tow. Choosing the correct type of trailer rating of any component of your towing system. See the CURT hitch requires knowing the gross trailer weight and the tongue hitch application guide on page 38 for specific hitch availability.
Class I & II Class III, IV & V 1 1/4" x 1 1/4" Receiver Tube Opening 2" x 2" Receiver Tube Opening
Up to 3,500 lbs. 3,500 lbs. to 12,000 lbs. GTW GTW Up to 350 lbs. 350 lbs. to 1,200 lbs. TW TW Not applicable Up to 14,000 lbs. WD WD
WD Not applicable WD Up to 1,400 lbs. TW TW
Xtra Duty & Xtra Duty+ Commercial Duty & Commercial Duty+ 2" x 2" Receiver Tube Opening 2 1/2" x 2 1/2" Receiver Tube Opening
16,000 to 17,000 lbs. 18,000 to 20,000 lbs. GTW GTW 2,400 to 2,550 lbs. Up to 2,700 lbs. TW TW Up to 17,000 lbs. 18,000 to 20,000 lbs. WD WD
WD Up to 2,550 lbs. WD Up to 2,700 lbs. TW TW
Front Mount Recreational Vehicle 2" x 2" Receiver Tube Opening 2" x 2" Receiver Tube Opening
Up to 5,000 lbs. 3,500 lbs. to 5,000 lbs. GTW GTW Up to 500 lbs. 350 lbs. to 500 lbs. TW TW 9,000 lbs. straight line pull 3,500 to 6,000 lbs. SLP WD
WD 350 to 600 lbs. TW
Passenger Car and Truck Styles Trunk hinges Trunk hinges at roof Truck: Truck: Vans, Minivans below window (including window) Chassis design Cab design SUVs and CUVs
Hinge Hinge
2-door coupe 3-door hatchback Short bed/Long bed Regular cab Van Hinge Hinge
4-door sedan 5-door hatchback Cab & Chassis Extended cab SUV/CUV Hinge
5-door wagon Dual rear wheels Crew cab Minivan
Quad cab Extended SUV
1.877.curtmfg • curtmfg.com • UNDERSTANDING TOWING • 11 Hitch Selection Guide Use this table to select the correct trailer hitch for the tow vehicle, based on trailer weight. Trailer hitch capacity is limited by the tow vehicle's capacity. Refer to owner's manual for the vehicle's maximum towing capacity. See page 38 for vehicle-specific application information.
Receiver 1 1/4" Up to 3,500 lbs. GTW Tube Size 2" Up to 17,000 lbs. GTW 2 1/2" Up to 20,000 lbs. GTW
Rec. Class and Tube Weight Rating Size Class I & II 1 1/4" Up to 3,500 lbs. Class III 2" Up to 6,000 lbs. Class IV 2" Up to 10,000 lbs. Class V 2" Up to 12,000 lbs. Xtra Duty 2" Up to 17,000 lbs. Commercial Duty 2 1/2" Up to 20,000 lbs. Note: Refer to owner's manual for vehicle's maximum towing capacity
Weight Capacity Guide Note: CURT Manufacturing recommends the use of trailer hitches showing a weight distributing (WD) rating when carrying a personal mobility vehicle (power wheel chair, scooter, etc.). By using a trailer hitch with a capacity lower than the gross trailer weight, the warranty may be voided and could result in damage to both the tow vehicle and the load.
Estimated Trailer Only Weights Aluminum trailer Fiberglass trailer 12-15' - Trailer weight: 200 lbs. Up to 17' - Trailer weight: 200 lbs. 16-20' - Trailer weight: 300 lbs. 18-20' - Trailer weight: 300 lbs. Boat 21-22' - Trailer weight: 570 lbs. Single axle Tandem axle 8' - Trailer weight: 320 lbs. 12' - Trailer weight: 1,200 lbs. 10' - Trailer weight: 360 lbs. 16' - Trailer weight: 1,300 lbs. Utility 20' - Trailer weight: 1,500 lbs. Motorcycles, ATVs, personal watercraft, snowmobiles Toy haulers Carries two (8') - Trailer weight: 350 lbs. 20' - Trailer weight: 4,100 lbs. Carries four (14') - Trailer weight: 980 lbs. 28' - Trailer weight: 6,600 lbs. Recreational vehicle 37' - Trailer weight: 12,000 lbs. Livestock trailers (gooseneck pull) Horse trailers (bumper pull) 16' - Trailer weight: 3,500 lbs. One horse - Trailer weight: 1,800 lbs. 20' - Trailer weight: 4,000 lbs. Two horses - Trailer weight: 3,100 lbs. Livestock/Horse 28' - Trailer weight: 5,000 lbs. Four horses - Trailer weight: 4,500 lbs. Campers 5th wheels 17' - Trailer weight: 2,300 lbs. 26' - Trailer weight: 5,900 lbs. 23' - Trailer weight: 4,200 lbs. 31' - Trailer weight: 7,800 lbs. Camper/5th Wheel 30' - Trailer weight: 4,800 lbs. 35' - Trailer weight: 10,200 lbs. For more information, contact the CURT Technical Support line at 800.798.0813.
12 • UNDERSTANDING TOWING • curtmfg.com • 1.877.curtmfg Towing Electrical Sub-Category Color Guide
CURT Manufacturing has identified eight sub-categories BRAKE TOWING ELECTRICAL PLUGS & BRAKE ELECTRICAL CONTROL CUSTOM ELECTRICAL within towing electrical. These make it easy for consumers ELECTRICAL CONVERTERS SOCKETS CONTROLS ADAPTERS HARNESSES WIRING TESTERS to quickly locate the product needed to properly wire their vehicleTOWING and trailer. EachELECTRICAL of the eight categoriesPLUGS & are color-BRAKE ELECTRICAL BRAKE CUSTOM ELECTRICAL ELECTRICAL CONVERTERS SOCKETS CONTROLS ADAPTERS CONTROL WIRING TESTERS coded and easily visible on all CURT retail packaging. HARNESSES
Wiring Systems CURT Manufacturing electrical products are designed to deliver unsurpassed levels of performance, reliability and durability. The use of surface mount technology (SMT) components is just one of the steps CURT has taken to achieve this. SMT components are the most up-to-date parts available for circuit designs. SMT components offer lower resistance, reduced heat generation and longer life cycles than more common, out-of-date, through-hole mounted components.
CURT applies SMT to a full-line of tail light converters and to any T-connector with a built-in converter.
Two-Wire Systems Three-Wire Systems Still common in the automotive industry and the simplest The most common in the automotive industry, while being form of trailer wiring. This system sends the stop/turn signal simple enough to wire with a converter of choice. The stop, along one wire, while the tail signal is separate. tail and turn signals are all sent on separate wires going into the converter, which then converts the signals to a two-wire system. Car side Trailer side Car side Trailer side
3-to-2 converter Stop Stop Stop Turn Turn Stop Turn Tail Tail Tail Turn Tail
Connector Connector
PWM Systems More and more vehicles on the market today use PWM (pulse width modulation) wiring systems, sometimes called 'multiplex' systems. These are systems that vary the signal intensity over a single wire to control more than one lighting function. There are two types: type STT (Stop / Turn / Tail) and type ST (Stop / Tail). PWM systems can be either incandescent or LED. STT Systems ST Systems These systems use a single wire to control the stop, tail These systems use a single wire to control the stop and tail and turn signals. For STT systems, use CURT tail light signals. Separate wires are used to control the left and right turn converter 56201. signals. For ST systems, use CURT tail light converter 56200. Car side Trailer side Car side Trailer side
PWM converter PWM converter Stop Stop Stop Turn Turn Stop Turn Tail Tail Tail Turn Tail
Connector Connector See the application guide on page 38 for a detailed listing of vehicles with ST and STT systems
1.877.curtmfg • curtmfg.com • UNDERSTANDING TOWING • 13 Electrical Adapter Selection Chart Often times it is necessary to use an adapter to match the wiring of the vehicle to the wiring of the trailer. Below is a chart to identify which adapters are needed, based on the customer's vehicle or trailer wiring.
Trailer Side Connectors
4-Way Flat 5-Way Flat 6-Way Round 7-Way RV Blade Nothing needed 5-way flat 4-way flat to 4-way flat to splice-in harness 6-way round adapter 7-way RV blade adapter
Suggested Part#: Suggested Part#: Suggested Part#: Suggested Part#: 4-Way Flat N/A 58531 57626 57676 Nothing needed Nothing needed 4-way flat to 4-way flat to 6-way round adapter 7-way RV blade adapter
Suggested Part#: Suggested Part#: Suggested Part#: Suggested Part#: 5-Way Flat N/A N/A 57626 57676 4-way round to 4-way round to 4-way 4-way round to 4-way flat Not applicable - 4-way flat adapter flat adapter and splice-in adapter and 4-way flat to Replace vehicle end wiring 5-way flat harness 6-way round adapter with 7-way RV blade
Suggested Part#: Suggested Part#: Suggested Part#: Suggested Part#: 4-Way Round 57225 57225 & 58531 57225 & 57626 N/A Vehicle Side Connectors Vehicle 6-way round to Not applicable - Nothing needed 6-way round to 4-way flat adapter Replace vehicle end wiring 7-way RV blade adapter with 7-way RV blade and use adapter
Suggested Part#: Suggested Part#: Suggested Part#: Suggested Part#: 6-Way Round 57621 57676 & 57251 N/A 57667 7-way RV blade to 7-way RV blade to 7-way RV blade to Nothing needed 4-way flat adapter 5-way flat adapter 6-way round adapter
Suggested Part#: Suggested Part#: Suggested Part#: Suggested Part#: 7-Way RV Blade 57241 57251 57261 N/A
14 • UNDERSTANDING TOWING • curtmfg.com • 1.877.curtmfg Common Plug Ends Per Trailer Type CURT offers a wide range of electrical components that vary as much as the trailers they connect to. Below are some examples of common trailers and the types of plug ends they have.
Common Corresponding Plug Ends Most Commonly Used Occasionally Used
Boat Trailer without Surge Brakes 4-Way Flat 7-Way RV Blade (rarely used)
Boat Trailer with Surge Brakes 5-Way Flat 6-Way Round or 7-Way RV Blade
Utility Trailer 4-Way Flat 6-Way Round or 7-Way RV Blade
Common Trailer Types Common Trailer Camper Trailer 7-Way RV Blade 6-Way Round or 7-Way RV Blade
5th Wheel Trailer 7-Way RV Blade 6-Way Round
Gooseneck Trailer 6-Way Round 7-Way RV Blade
1.877.curtmfg • curtmfg.com • UNDERSTANDING TOWING • 15 Plugs & Sockets and Adapter Wiring Guide Refer to the illustrations below for representative, rear views of plugs & sockets. The colors illustrated may not represent the colors found on the tow vehicle or trailer.
7-Way, RV Blade 7-Way, RV Blade Traditional Configuration SAE J2863 Configuration Vehicle Side Trailer Side Vehicle Side Trailer Side
Function Color Function Color Tail lights Green Tail lights Brown Left turn / brakes Red Left turn / brakes Yellow Ground White Ground White Electric brakes Blue Electric brakes Blue Right turn / brakes Brown Right turn / brakes Green +12 volt Black +12 volt Orange Reverse lights Yellow Reverse lights Grey
7-Way, Round 6-Way, Round 4-Way, Round Vehicle Side Trailer Side Vehicle Side Trailer Side Vehicle Side Trailer Side
Function Color Function Color Function Color Tail lights Brown Tail lights Brown Tail lights Brown Left turn / brakes Yellow Left turn / brakes Yellow Left turn / brakes Yellow Ground White Ground White Ground White Electric brakes Blue Electric brakes Blue Right turn / brakes Green Right turn / brakes Green Right turn / brakes Green Auxiliary power Red +12 volt Black Reverse lights Purple
5-Way, Flat 4-Way, Flat Vehicle Side Trailer Side Vehicle Side Trailer Side
Function Color Function Color Tail lights Brown Tail lights Brown Left turn / brakes Yellow Left turn / brakes Yellow Ground White Ground White Right turn / brakes Green Right turn / brakes Green Reverse lights Blue
16 • UNDERSTANDING TOWING • curtmfg.com • 1.877.curtmfg TOWING GLOSSARY A B Brake Control Interface between tow vehicle and electric trailer brakes. Can be motion- All-Purpose Vehicle (APV) Ball activated or based on time delay Typically a minivan. Offers more Also referred to as trailer ball or hitch from activation of the vehicle brakes. seating and higher load capacities ball. The ball-shaped attachment to Typically located in the tow vehicle's than passenger cars a hitch onto which a trailer coupler is driving compartment with electrical attached. The coupler mounts and line running to the trailer wiring locks on top of the trailer ball and connector. Most require the user to All-Terrain Vehicle (ATV) articulates around the trailer ball. adjust brake gain to compensate for varying trailer load. Necessary for the Also known as a quad or four-wheeler Recreational and light commercial trailer balls come in a variety of sizes use of electric trailer brakes including 1 7/8", 2", 2 5/16" and All-Wheel Drive (AWD) occasionally, 3". In general, lighter trailers use smaller trailer balls. While Breakaway Switch AWD is a system that powers all the diameter of trailer balls is fairly A component within a breakaway four wheels all of the time, much like standard, shank diameters and the system that is attached to both 4WD. Some automatic all-wheel drive trailer ball weight capacity may differ. the tow vehicle and the trailer vehicles are essentially smart 2WD The rating of the trailer ball is just as systems. These systems give you important as the rating of the trailer hitch more traction when you need it, but Breakaway System they generally will not activate until A safety system that activates the your vehicle needs the added traction Ball Height (Euro Mount® only) trailer brakes in the event the trailer Measurement from the ground to becomes accidentally disconnected ® Application Guide the top of the Euro Mount ball when from the vehicle while traveling parked on a flat surface and parallel to A complete listing of current part the ground. Used to determine which numbers and the associated vehicle ® Euro Mount is required to make sure Bumper applications the trailer rides parallel to the ground The parts on a vehicle that protect the while being towed front and rear ends in the event of an Axle accident. Some trucks and SUVs have a tow bumper (or step bumper) for Ball Mount Central shaft for a rotating wheel or attaching a trailer ball for towing. See gear. The axle may be permanently Also known as drawbar or hitch bar. quick reference chart of bumper styles fixed to the wheels, rotating with them, A removable trailer ball platform that or fixed to its surroundings, with the slides into the receiver tube opening of wheels rotating around the axle. a trailer hitch and fastens with a pin & Bumper Hitch One axle has two wheels clip. Different ball mounts can be used Hitch that attaches to a vehicle's bumper to raise or lower the height of the ball to allow for level trailer towing Bumper Pull Trailer Bolt-on Hitch (Fixed-Tongue) A trailer that is pulled behind a vehicle with a chassis mounted trailer hitch as Attaches directly to the tow vehicle opposed to a 5th wheel or gooseneck providing the connection between hitch. Also called a tag-along trailer the tow vehicle and the trailer. A fixed- tongue hitch permanently includes the ball platform, in contrast to a 1 1/4", 2" or 2 1/2" receiver hitch, which has an opening for inserting ball mounts or other accessories. Denoted by an 'L' footnote in the CURT application guide
1.877.curtmfg • curtmfg.com • UNDERSTANDING TOWING • 17 Bungee Cords Class III Trailer Hitch Commercial Duty + (CD+) Hitch Cords composed of rubber or several Trailer hitch with a carrying capacity Trailer hitch with a carrying capacity elastic strands covered with nylon or of 3,500 to 8,000 lbs. gross trailer of 20,000 lbs. gross trailer weight cloth and have metal or plastic hooks weight and 350 to 800 lbs. tongue and 2,700 lbs. tongue weight. When on each end. These are available in weight. When used in conjunction used in conjunction with a weight nearly any length to secure light cargo with a weight distribution system, the distribution system, the weight ratings weight ratings increase up to 12,000 remain equal to the carrying capacity. lbs. gross trailer weight and up to Has a 2 1/2" receiver tube opening 1,200 lbs. tongue weight. Has a 2" x 2" receiver tube opening C Computer Numerical Control (CNC) Class IV Trailer Hitch Cargo Carrier The automated control of work piece Trailer hitch with a carrying capacity or tool motions with input parameters The cargo carrier is a hitch-mounted of up to 10,000 lbs. gross trailer such as feed, speed and depth of cut. platform that typically has up to a 500 lbs. weight and up to 1,000 lbs. tongue Commonly used in manufacturing capacity. Common uses include hauling weight. When used in conjunction with coolers, boxes, tools, firewood and a weight distribution system, the weight other items unable to fit in the vehicle. ratings increase up to 12,000 lbs. Connector They are usually offered with a short 2" gross trailer weight and up to 1,200 lbs. wall or a higher 6" wall and may include Electrical term used to define tongue weight. Has a 2" x 2" receiver a tilt feature allowing the carrier to fold components for joining wires tube opening up when not in use
Converter (Tail Lights) Class V Trailer Hitch Chassis Converts three-wire tow vehicle Trailer hitches with a 2 1/2" x 2 1/2" The main framework of a vehicle. It electrical systems to two-wire systems, receiver tube opening have a carrying consists of the frame, and only the integrating the stop and turn signal capacity of up to 20,000 lbs. gross essential parts needed for operation. circuits as is common in trailer wiring trailer weight and up to 2,700 lbs. Vehicle body and other non-essential tongue weight. Trailer hitches with parts are not considered part of the a 2" x 2" receiver tube opening have chassis Coupler a maximum gross trailer weight of 17,000 lbs. and a maximum tongue The forward most part of a trailer tongue that envelopes and secures Class I Trailer Hitch weight rating of 2,550 lbs. Due to the already high weight ratings, when to the tow vehicle trailer ball Trailer hitch with a capacity of up to used in conjunction with a weight 2,000 lbs. gross trailer weight and up to distribution system, the weight 200 lbs. tongue weight. Has an ratings do not increase. Coupler Height 1 1/4" x 1 1/4" receiver tube opening The distance from the ground to the bottom of the trailer coupler with the Clip trailer tongue leveled. The coupler Class II Trailer Hitch Used to retain the pin in a trailer hitch height and hitch height are used to Trailer hitch with a capacity of 2,500 to determine the drop or rise needed 3,500 lbs. gross trailer weight and 250 when selecting a ball mount to 350 lbs. tongue weight. Has an Commercial Duty (CD) Hitch 1 1/4" x 1 1/4" receiver tube opening Trailer hitch with a carrying capacity Coupler Lock of 18,000 lbs. gross trailer weight and 2,700 lbs. tongue weight. When A pin style lock designed to fit through used in conjunction with a weight the coupler's latching mechanism, distribution system, the weight ratings disabling it from latching to or being remain equal to the carrying capacity. removed from the trailer ball, preventing Has a 2 1/2" receiver tube opening unwanted use or removal of the trailer
18 • UNDERSTANDING TOWING • curtmfg.com • 1.877.curtmfg Crossover Dry Weight Fifth Wheel Trailer (5th Wheel) Also called crossover utility vehicle or A technical term that refers to the 5th wheel trailers are trailers designed CUV. A vehicle built on a car platform, weight of an automobile or trailer to be coupled to a special hitch that but uses styling and features common without any fluids, passengers or cargo is mounted over the rear axle in the on sport utility vehicles or SUVs bed of a pickup truck. These trailers can have one, two or three axles, Dually and are the largest type of trailer ( ) Crossover Utility Vehicle CUV A pickup truck with four wheels on the built. Because of their special hitch A vehicle built on a car platform, but rear axle (two wheels on each side). requirements, 5th wheel trailers can uses styling and features common on Dually's are better for towing and only be towed by trucks or specialized sport utility vehicles or SUVs can take a heavier load compared to vehicles prepared for 5th wheel trailer regular rear ends compatibility
Curb Weight Fishwire The total weight of a vehicle with factory equipment, all necessary fluids, Used during hitch installation; a small (coolant, oil, etc) a full tank of gas and E wire device that allows you to "fish" minus any passengers or cargo or pull hardware through an enclosed Equalizer frame or bumper tube This term is sometimes is used for Custom Hitch a weight distribution system; a hitch Fixed-Tongue Hitch A trailer hitch that is designed for a system built around a trailer hitch that A device that attaches directly to the particular year, make and model of includes supplemental equipment tow vehicle providing the connection vehicle. These hitches are made for a such as spring bars, which can be between the tow vehicle and the trailer. specific vehicle so the best possible fit placed under tension to distribute A fixed-tongue hitch permanently and appearance can be achieved trailer tongue loads to the trailer includes the ball platform, in contrast axle(s) and the tow vehicle front axle. to a 1 1/4", 2" or 2/12" trailer hitch, Use of a weight distribution system which has an opening for inserting ball enhances handling and braking while mounts or other accessories increasing trailer towing capacity. D Weight distributing hitches currently come in two configurations: one with Forged Dinghy square bars that hook to the center of the ball mount, called trunnion bars; A manufacturing process involving A vehicle towed behind a motor home. and one with round bars that slide into the shaping of metal using localized Can be towed with two wheels on a tow the bottom of the ball mount, called compressive forces. Forging can dolly or with all four wheels on the ground round bars produce a piece that is stronger than an equivalent cast or machined part
Drawbar Also known as ball mount or hitch Four-Wheel Drive (4WD) bar. A removable trailer ball platform F A drivetrain that allows all four that slides into a hitch's receiver tube wheels to receive power from opening and fastens with a pin & clip, Fifth Wheel Hitch (5th Wheel) the engine simultaneously or the tongue portion of a fixed-tongue hitch. The term drawbar is sometimes A heavy duty hitch that uses a plate used to distinguish a ball mount or a and locking jaws and is located in the Frame coupling configuration different than a bed of the truck (similar to a semi- The part of a vehicle in which trailer ball (such as a pintle hook) tractor.) The kingpin is located on the trailer all other parts attach to
Dry Rot When tires are left exposed to prolonged sunlight, decaying the rubber. Regular usage and/or covers will prevent this
1.877.curtmfg • curtmfg.com • UNDERSTANDING TOWING • 19 Frame Mount Hitch Gross Axle Weight ( ) H Trailer hitch that is designed to be Rating GAWR bolted to the vehicle frame or cross The manufacturer's rating for the members. This type of hitch may have maximum allowable weight that an Hand Wheel a permanent ball mount or may have axle is designed to carry. GAWR The threaded, turnable wheel on top a receiver tube opening into which applies to tow vehicles, trailers, of a trailer coupler that tightens or a removable ball mount or shank is 5th wheels and motor home axles loosens the coupler assembly around installed. Has a 2" x 2" receiver tube the trailer ball opening Gross Combination Weight Rating (GCWR) Handle Nut Front Mount Hitch The maximum allowable weight of the An in-frame mounting point which A trailer hitch that mounts to the combination of tow vehicle and trailer, can be inserted from an access hole frame at the front of a vehicle. They 5th wheel or motor home and dinghy. or other hard to reach places are available for several trucks, It includes the weight of the vehicle, full-sized vans and SUVs. This trailer, 5th wheel or dinghy, cargo, provides a convenient mount for hitch passengers and all fluids Hitch accessories. Front mount hitches can also be used for easy maneuvering at A device which attaches directly to the the boat landing or campground. Has Gross Combined (Vehicle) tow vehicle providing the connection a 2" x 2" receiver tube opening Weight (GCW or GCVW) between the tow vehicle and the trailer. A fixed-tongue hitch permanently The actual total combined weight includes the ball platform, in contrast of a vehicle and trailer, including all Front-Wheel Drive (FWD) to a 1 1/4", 2" or 2/12" trailer hitch, passengers and cargo which has an opening for inserting Engine/transmission layout where the ball mounts or other accessories engine drives the front wheels only Gross Trailer Weight (GTW) The total weight of the trailer fully Hitch Adapter loaded in its actual towing condition An item that fits into the receiver G tube opening of a hitch and increases or decreases the receiver's size to Gross Vehicle Weight (GVW) allow fit with other shank sizes. Using Gooseneck Hitch Total weight of vehicle when fully loaded, a hitch adapter may reduce the overall A towing system that mounts a trailer including all passengers and cargo capacity to the rating of the adapter ball in the bed of a pickup truck (either being used 2 5/16" or 3" in diameter) to engage a coupler on a trailer Gross Vehicle Weight Rating (GVWR) Hitch Ball The maximum operating weight Also referred to as ball or trailer ball. Gooseneck Trailer of a vehicle as specified by the The ball-shaped attachment to a Derives its name from its shape. A manufacturer. It includes the vehicle's hitch onto which a trailer coupler is gooseneck trailer typically uses a ball chassis, body, engine, engine fluids, attached. The coupler mounts and and socket coupling, kingpin or other fuel, accessories, driver, passengers locks on top of the trailer ball and similar trailer connection method and cargo articulates around the trailer ball. located above and forward of the Recreational and light commercial rear most axle of the towing vehicle trailer balls come in a variety of sizes including 1 7/8", 2", 2 5/16" and occasionally, 3". In general, lighter Gross Axle Weight (GAW) trailers use smaller trailer balls. While the diameter of trailer balls is fairly The total weight supported by standard, shank diameters and the each vehicle's axle (front or rear) trailer ball weight capacity may differ. The rating of the trailer ball is just as important as the rating of the trailer hitch
20 • UNDERSTANDING TOWING • curtmfg.com • 1.877.curtmfg Hitch Bar Hitch Tube Cover K Also know as ball mount or drawbar. A temporary end-cap placed into A removable trailer ball platform that a hitch's receiver tube opening. slides into the receiver tube opening Designed to protect the receiver tube Kingpin of a hitch and fastens with a pin & clip. from the elements. Also used to mask The point at the center of a 5th wheel Different ball mounts can be used or enhance the look of the hitch when trailer's nose which is captured by to raise or lower the height of the ball not in use the locking bar or jaws of a 5th wheel to allow for level trailer towing hitch. The circular shape of the kingpin allows the trailer to rotate freely within Hitch Weight the 5th wheel hitch to allow for proper Hitch Class Also known as tongue weight. The turning and maneuvering Defines receiver tube opening size downward weight applied on the trailer and weight rating capacity for trailer ball. Generally, hitch weight should not hitches exceed 15% of the gross trailer weight L Hitch Extender An item that fits into the receiver tube Landing Gear opening of a hitch and can extend the I Commonly used on gooseneck and 5th receiver tube several inches. Using a wheel trailers to stabilize the trailer when hitch extension may reduce the overall Insert not being towed. Also used to raise and capacity to the rating of the extender Any item that slides into the receiver lower the trailer height when coupling and being used tube opening of a trailer hitch uncoupling. Always be sure to completely raise the landing gear before towing Hitch Height The distance from the ground to LED (Light-Emitting Diode) the top of the hitch's receiver tube J Requires less amperage than opening, with the vehicle parked on traditional bulbs to illuminate level ground. The hitch height and the J684 Standard (V-5) coupler height are used to determine the drop or rise needed when selecting Testing standard designed by the Locking Pin a ball mount Vehicle Equipment Safety Commission to increase highway safety by reducing Hitch pin that locks with a key to prevent towing and hitch-related accidents. theft of a ball mount or other insert Hitch Lock This regulation is not intended to cover 5th wheel and pintle hook connecting A locking pin designed to secure a ball devices or towing methods Long Bed (LB) mount or other hitch-mounted accessory to the hitch, preventing theft Usually a foot or two longer than short beds. Compact long beds are J2638 Standard generally 7' long and full-size are Hitch Pin Testing standard designed to establish generally 8' long minimum performance criteria for Also called a pin or receiver pin. a towing vehicle and fifth wheel Holds the ball mount in the hitch. or gooseneck trailer at or below Lunette Eye Typically bent like a hockey stick and 30,000 lbs. gross trailer weight. This drilled at one end to accept a hairpin- A round metal ring used in place of establishes criteria for the hitch, tow shaped retaining clip a ball coupler on a trailer. It attaches vehicle attachment structure, trailer to a pintle hook on the towing vehicle attachment structure and coupling Hitch Ratings Hitches are rated according to the Jackknife maximum amount of weight they are When an extreme angle occurs engineered to handle. See class I between the vehicle and trailer. through V trailer hitches Jackknife occurs during improper breaking or from poor road conditions
1.877.curtmfg • curtmfg.com • UNDERSTANDING TOWING • 21 M Pintle Hitch R A common heavy duty coupling type which utilizes a pintle hook attached to Multi-Fit Hitch a tow vehicle to pull a trailer having a Ratchet Strap Also known as a universal hitch. lunette eye. Pintle hitches are commonly A nylon strap attached to a ratcheting Fits a number of different vehicles used on military, construction, assembly designed to secure cargo. industrial and agricultural equipment The ratcheting assembly allows the strap to be tightened, eliminating the Multi-Plex unwanted movement of a load. Typically Pintle Hook Also called PWM. Commonly used straps have metal hooks on each end technique for controlling power to The jaw portion of a pintle hitch which inertial electrical devices attaches to the tow vehicle Rear-Wheel Drive (RWD) Engine/transmission layout where the Pintle Mount engine drives the rear wheels only An insert for a trailer hitch's receiver O tube opening, which has a shank with a flat plate. These mounts are typically Receiver Pin Original Equipment adjustable for vertical height Also called a hitch pin or pin. Holds Manufacturer (OEM) the ball mount in the hitch. It is also a convenient attachment point for OEM designates a replacement Plug breakaway cables. Typically bent like part made by the manufacturer The connector used to connect trailer a hockey stick and drilled at one end to of the original part wiring to a tow vehicle. Plug refers to accept a hairpin-shaped retaining clip the trailer end of the connection.
Receiver Tube ( ) P Powered Converter Tail Lights The receptacle part of a trailer hitch Converts the tow vehicle's three-wire which accommodates inserts such as ball mounts, draw bars or cargo Payload electrical system to a two-wire system, integrating the stop and turn signal carriers The transported load. Freight excluding circuits, which is common in trailer the weight of the trailer or tow vehicle wiring. This converter will be powered by the vehicle's battery, allowing the Recreational Vehicle (RV) trailer lights to be illuminated with The usual term for a motor vehicle or Personal watercraft (PWC) virtually no draw on the vehicle tail trailer equipped with living space and A recreational watercraft that the rider light circuit. Powered converters are amenities found in a home sits or stands on, rather than inside of, recommended on most vehicles with as in a boat. They are often referred to LED tail lights as the trademarked brand names Jet Roll Pan Ski, Wave Runner or Sea-Doo Pulse Width Modulation (PWM) A fascia panel used in place of a rear bumper (common on lowered trucks). Also called multi-plex. Commonly used Installation of a roll pan may interfere Pin technique for controlling power to with placement of a bolt-on hitch Also called a hitch pin or receiver pin. inertial electrical devices Holds the ball mount in the hitch. It is also a convenient attachment point for Round Bar breakaway cables. Typically bent like A type of weight distributing hitch a hockey stick and drilled at one end to that has round bars that slide into the accept a hairpin-shaped retaining clip bottom of the WD hitch head. This differs from the trunnion style, which has square bars that attach to the center of the hitch head
22 • UNDERSTANDING TOWING • curtmfg.com • 1.877.curtmfg Round Tube Hitch Stabilizing Strap T A new generation of custom hitches Auxiliary strap used for added support designed to produce a more pleasing to unsupported loads such as a bike visual appearance. The use of round rack or cargo carrier T-Connector tubing lowers the weight of the hitch Application-specific wiring harness. itself, while maintaining its capacity. T's into existing tow vehicle wiring These hitches are designed to Sub-Frame complement the look of the vehicles The part of the vehicle which supports for which they are made the engine and front suspension on a Tandem Axle uni-body vehicle Two fixed axles (four wheels)
S Surge Brake System Tongue Weight (TW) A surge brake system is entirely Also known as hitch weight. The self-contained on the trailer and Safety Chains downward weight applied by the is activated when the tow vehicle towable equipment on the hitch ball. The chains that are attached to the decelerates. The entire activation Generally, tongue weight should trailer tongue with hooks on their free process is completed in less than not exceed 15% of the gross trailer ends. In emergency situations these one second. Hydraulic surge brake weight. To measure the tongue chains will keep the trailer connected systems can be used by a variety of weight use either a commercial to the tow vehicle in case the coupler tow vehicles and can accommodate scale or a bathroom scale with the or trailer ball detach from the tow a variety of trailer loading conditions coupler at towing height. When using vehicle. Federal law requires safety without requiring any type of adjustment a bathroom scale, use the method chains to be secured while towing shown on page 9 and multiply the scale reading by three Sway Shank Also known as 'yaw'. Refers to the The part of the ball mount or insert that fish-tailing action of a trailer caused Torque slides into the trailer hitch's receiver tube by external forces that set the trailer's A measure of the turning force on an opening mass into a lateral motion. The trailer's object such as a bolt or a flywheel. For wheels serve as the axis or pivot point example, pushing or pulling the handle of a wrench connected to a nut or bolt Short Bed (SB) produces torque (turning force) that Sway Bar Usually a foot or two shorter than loosens or tightens the nut or bolt a long bed. Typically 5' to 6' long A specialized spring which is part of the suspension on a vehicle, not part of a trailer hitch. Sometimes confused Tow Bar Socket with a weight distributing hitch A device attached to the front of a vehicle Wiring connector used on the car end which allows it to be towed by another of a trailer wiring connection. Socket vehicle while riding on its own wheels Sway Control Device refers to the vehicle end A device which goes between a weight distributing ball mount and a trailer to Tow Dolly Sport Utility Vehicle (SUV) reduce the likelihood of sway caused Small trailer that is little more than by passing vehicles and wind. This Term for a vehicle similar to a station two wheels, an axle and a coupler, device should not be used to correct wagon, but built on a light-truck used to tow a front-wheel drive sway caused by improper tongue chassis. It is usually equipped with four- vehicle behind a recreational vehicle weight (too little or too much) wheel drive for on or off-road ability or other larger vehicle
Spring Bar Key component of a weight distributing hitch system. Spring bars work to distribute trailer tongue loads to the forward axle of the tow vehicle
1.877.curtmfg • curtmfg.com • UNDERSTANDING TOWING • 23 Tow Rating Trailer Electrical Adapter Two-Wheel Drive (2WD) The vehicle manufacturer's rating Converts the car-side trailer connector A drivetrain that allows two wheels of the maximum weight that can to a compatible mate for the trailer to receive power from the engine safely be towed by a particular connector (i.e. 4-way flat to 7-way RV) simultaneously vehicle. Tow ratings are related to overall trailer weight, not trailer size, in most cases. However, some tow Trailer Hitch ratings impose limits as to frontal A device which attaches directly to the area of the trailer and overall length. tow vehicle providing the connection U Tow ratings are determined by the between the tow vehicle and the trailer. vehicle manufacturer according to See hitch Uni-Body several criteria, including engine size, transmission, axle ratio, brakes, A vehicle that has an integrated frame and body. Usually has a sub-frame for chassis, cooling systems and other Trailer Jack special equipment the front end which mounts the engine A device used for supporting, raising and suspension and lowering the trailer tongue Tow Vehicle Universal Hitch Vehicle that pulls a trailer or dolly Trailer Lock Also known as a multi-fit hitch. A lockable, simulated ball assembly used Fits a number of different vehicles Trailer Ball to prevent unwanted trailer use or theft Also referred to as ball or hitch ball. USCAR (United States Council The ball-shaped attachment to a Trailer Tongue for Automotive Research) hitch onto which a trailer coupler is attached. The coupler mounts and The part of the trailer which extends A group that attempts to communize locks on top of the trailer ball and forward from the trailer box and components on vehicles. A type of articulates around the trailer ball. includes the coupler electrical connection that has been Recreational and light commercial used commonly on GM, Ford and trailer balls come in a variety of sizes Toyota trucks since 1999. Dodge including 1 7/8", 2", 2 5/16" and Transmission Cooler has their own, distinct version occasionally, 3". In general, lighter An auxiliary cooler that is available to trailers use smaller trailer balls. While provide extra cooling for automatic the diameter of trailer balls is fairly transmission fluid. Lower temperatures standard, shank diameters and the lead to longer transmission life trailer ball weight capacity may differ. V The rating of the trailer ball is just as important as the rating of the trailer hitch Travel Trailer V-5 Also known as conventional trailers. Testing standard designed by the These types of trailers are bumper pull Trailer Brakes Vehicle Equipment Safety Commission trailers with an A-frame and a coupler. to increase highway safety by reducing Brakes that are built into the trailer Travel trailers are available with one, two towing and hitch-related accidents. axle systems and are activated either or three axles This regulation is not intended to cover by electric impulse or by a surge 5th wheel and pintle hook connecting mechanism. The majority of RVs utilize devices or towing methods electric trailer brakes that are actuated Tri-Axle when the tow vehicle's brakes are Three fixed axles, six wheels operated or when a brake controller is manually activated. Surge brakes utilize a mechanism positioned at the Trunnion Bar coupler that detects when the tow vehicle is slowing or stopping and A type of weight distributing hitch activates the trailer brakes via that has square bars that attach a hydraulic system to the center of the WD hitch head. This differs from the round bar style, which has round bars that slide into the bottom of the hitch head
24 • UNDERSTANDING TOWING • curtmfg.com • 1.877.curtmfg V-19 Weight Distribution Hitch X Testing standard designed by A hitch system built around a trailer the Vehicle Equipment Safety hitch which includes supplemental Commission to increase highway equipment such as spring bars that Xtra Duty (XD) Hitch safety by reducing towing-related can be placed under tension to distribute Trailer hitch with a carrying capacity accidents. This regulation is intended trailer tongue weight to the trailer of 16,000 lbs. gross trailer weight to cover towing methods associated axle(s) and the front axle of the tow and 2,400 lbs. tongue weight. When with 5th wheel and gooseneck trailer vehicle. Use of a weight distribution used in conjunction with a weight tongues connecting to kingpin or ball system enhances handling and braking distribution system, the weight ratings and socket couplers located above and may increase trailer towing are 17,000 lbs. gross trailer weight and and forward of the rear most axle capacity. Weight distributing hitches up to 2,400 lbs. tongue weight. Has a of the towing vehicle currently come in two configurations: 2" x 2" receiver tube opening one with square bars that attach to the center of the WD hitch head, called Vehicle Identification trunnion bars; and one with round bars Xtra Duty + (XD+) Hitch Number (VIN) that slide into the bottom of the hitch head, called round bars Trailer hitch with a carrying capacity A unique serial number used by of 17,000 lbs. gross trailer weight the automotive industry to identify and 2,550 lbs. tongue weight. When individual motor vehicles Weldnuts used in conjunction with a weight distribution system, the weight ratings Nuts welded to the vehicle are 17,000 lbs. gross trailer weight and frame or their installation plates 2,550 lbs. tongue weight. Has a 2" x 2" W receiver tube opening Wheelbase (WB) Weight Carrying Hitch (WC) The horizontal distance between the center of the front wheel and the center Any hitch used without a weight of the rear wheel distributing system. Some hitches are designed and clearly marked weight carrying only. Some hitches are weight Wiring Harness carrying with weight distributing ability and will have a dual rating. For example, Electrical wiring setup for a vehicle weight carrying (WC) 5,000 lbs. and weight distributing (WD) 10,000 lbs. To use a hitch at the higher rating (WD), a Wiring System weight distribution system must be added Type of wiring configuration, two-wire or three-wire, based on the vehicle Weight Distributing (WD) A towing situation where some or all of the tongue weight is redistributed to the trailer axle(s) and throughout the vehicle chassis instead of only the vehicle's rear axle. This is accomplished by the use of a weight distribution hitch
1.877.curtmfg • curtmfg.com • UNDERSTANDING TOWING • 25