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Glossary of Off-Road Terminology

There are many approaches to beefing up your 4x4 for the trails, with an array of off-road components to choose from. We define the terms and hardware you’ll come across.

If you're looking to beef up your 4x4 to take it off-roading, chances are you've been reading about all the ways it's possible to improve a truck and get it ready for the trails. There are so many different approaches to the subject and so many differing opinions, your head may start spinning. We know starting from scratch can be confusing, especially if you're undertaking something you've never been involved with before.

We've found that the customers who get full enjoyment out of off-roading start with suspension improvements, then move on to protection against body damage. Then they graduate to bigger wheels and tires, and finally, accessories like winches. In order to help you gain an understanding of these essential off-roading components, we've created the following glossary of terms.

Ackerman Angle

Ackerman Angle

(Also known as "toe-out turns".) The turning angle of an inside wheel is different than the turning angle of the outside wheel to account for the fact that the inside wheel travels a shorter path. This difference, which is an engineered value, is called the Ackerman angle.

Add-a-Leaf

Add-a-Leaf

This term refers to an affordable technique for lifting a vehicle equipped with leaf springs. An extra leaf spring is inserted into the leaf spring pack (see Photo #2) to achieve a higher ride height than the stock OEM setup (Photo #1.)

Amp Draw

The amount of ampere-hours consumed by a piece of electrical equipment such as a winch during operation. An ampere-hour is a measure of the energy a battery can hold and supply at a specific voltage.

Approach Angle

Approach Angle

The steepest angle a vehicle can climb or descend before its front bumper, body, chassis, or equipment mounted there make contact with the ground. Approach angles can be improved for off-roading with the installation of various lift kits to increase ride height.

Articulation

Articulation

A suspension's capacity to combine compression ("bump") and droop on one axle over uneven terrain. Ideally, the body remains generally level while the axles work at extreme angles to navigate uneven ground.

Bead Lock

Bead Lock

A series of metal reinforcement rings that clamp a tire to a rim to provide greater resistance from the tire popping off the wheel under extreme off-road conditions, or when tire pressures have been lowered for rock crawling.

Bed Bar

Bed Bar

A steel bar assembly (usually made from tubular bars) that can be bolted or welded to your truck bed. Typically, bed bars are more for style, and they don't offer the safety of a roll bar should your truck flip over off-roading. They are extremely useful for mounting off-road lights.

Breakover Angle

Breakover Angle

(Also known as "ramp break over angle.") The degree of slope that defines the largest ramp or hill that a vehicle can travel over without scraping its mid-section between front and rear wheels against the ground.

Bridle

Bridle

A form of winch strap or tow strap that's designed be attached to two separate points such as the right and left chassis members of a vehicle. At its center where the straps meet, a bridle serves as a point of attachment for a tow rope, hook, etc.

Bull Bar

Bull Bar

An assembly that bolts to the front structure of a vehicle which is designed to protect the center and underside of the front bumper from damage caused by frontal and underside impacts. Bull bars serve to block crash energy from reaching softer front body panels, channeling it directly to the vehicle's structure. Bull bars usually include skid plates on their underside.

Bumper Bar

Bumper Bar

A tubular metal reinforcement assembly with two bars designed to offer full protection for a front or rear bumper area during minor parking speed impacts. Bumper bars mount to steel framework under the vehicle rather than to the bumper itself, and offer minimal protection during off-roading.

Center of Gravity

Center of Gravity

A theoretical spot on a vehicle where all planes are balanced - from-left-to-right as well as front-to-rear. A vehicle's center of gravity (CoG) reflects how easily that vehicle will roll over. A high center of gravity makes a vehicle more top-heavy and more likely to tip over. For many off-road vehicles (especially lifted ones), the center of gravity is a foot or two above the ground and slightly forward from the center. Because this spot is higher than what's found on cars, 4x4s are more likely to tip over when off-roading.

Coordinated Tow

When recovering a stuck vehicle, engine throttle of the rescue vehicle and stuck one are applied at the same time to increase the odds of a first-time recovery.

Dead-Man

Dead-Man

A fixed anchor point used during winching, such as a tree or anything else sturdy enough to remain stationary when force is applied against it.

Departure Angle

Departure Angle

The steepest angle a vehicle can climb or descend before its rear bumper, body, chassis, or equipment mounted there make contact with the ground.

D-Ring

D-Ring

A heavy-duty, D-shaped steel hook used at the end of tow straps, chains, or cables used for pulling or winching a vehicle out of trouble.

D-Ring Attachment

D-Ring Attachment

A metal eyehole plate that's bolted or welded in place in order to serve as an anchor point for heavy-duty metal D-rings or other hooks. D-ring attachments can be found on some bumpers, grille guards, bull bars, and other similar reinforcements.

Drum Storage Capacity (Winching)

Drum Storage Capacity

(Also known as "Cable Capacity on the Spool".) The maximum length of cable or wire rope that can be wound around a drum without exceeding the maximum number of layers. It is expressed in feet or meters, and can vary depending on the thickness and diameter of the cable.

Duty Cycle

Duty Cycle

The operating cycle of a machine or other device (especially an electrical one) that operates intermittently rather than continuously. "Duty cycle" is a number representing "ON" time as a percentage of one complete on-off cycle. The total length of the cycle is irrelevant. For example, a 25% Duty Cycle as illustrated above means the device is "ON" for 25% of the time, and "OFF" for 75% of the time. If the complete on-off cycle is 1 minute (60 seconds), the "ON" time is 15 seconds (60 x .25), and the "OFF" time is 45 seconds (60 x .75). Winches have duty cycles in order to avoid overheating.

Duty Cycle Thermal Rating

On a winch, the distance a specified load can be hoisted and lowered before the lubricating oil rises from 100°F to a 250°F (or other) maximum gear oil temperature.

Fairlead

Fairlead

A steel guide installed onto a winch mount to help direct the winch cable. A Hawse type fairlead (shown on the left) features a simple bracket with curved edges for the cable to slide against, and a roller type fairlead (shown on right) uses moving rollers on all four sides to reduce friction.

Grille Guard - Center

Grille Guard - Center

An assembly that bolts to the front structure of a vehicle designed to protect the center area of the front bumper and grille from damage caused by straight-on frontal impacts. Grille guards serve to block crash energy from reaching softer front body panels, channeling it directly to the vehicle's structure.

Grille Guard - Full

Grille Guard - Full

This is essentially a center grille guard (see definition above) with extra attachments that wrap around and protect headlight assemblies.

Ground clearance

Ground Clearance

Space between the ground and the lowest-lying part of a vehicle's underside. Depending on the vehicle, that lowest part may be an axle differential, part of the exhaust system, or other component. Ground clearance is improved with the installation of a suspension lift kit.

High-centered

High-Centered

When a vehicle is stuck because its mid-section has become lodged over obstacles or ground, with front and rear wheels too far off the ground to achieve sufficient breakaway grip.

Lift-block

Lift-Block

Also known as "spacer block". A spacer placed between a rear axle assembly and springs to provide an inexpensive ride height boost that's suitable for off-roading.

Lift Kit

A set of components that raise the ride height of a vehicle. Lift kits range from complete ones with taller springs, shocks, and control arms down to simpler components such as spacer blocks which simply bolster the height of existing springs, or the height of the body from its frame.

Limited-slip differential

Limited-Slip Differential

Final-drive system where left and right axle shafts are mechanically connected via a series of pinion gears to prevent wheel spin on slippery surfaces and to ensure that the engine's power is transmitted equally both sides of the vehicle.

Line

Line

A driver-selected path that provides the best route for a 4x4 to climb over an obstacle or through multiple ones. Choosing the right line is essential to successful four-wheeling.

Locked in

Locked in

When manually adjustable front axle hubs are moved from freewheeling 2-wheel-drive and locked into position in 4-wheel-drive mode.

Locker

Locker

A device in either the front or rear differential that sends engine power to both wheels regardless of traction.

Off-Camber

Off-Camber

A situation where a vehicle is sideways enough on an incline to increase chances of a rollover.

Off-Road Bumper

Off-Road Bumper

A front or rear replacement bumper (typically made from heavy gauge steel) that features angled corners and edges that provide extra ground clearance. Where OEM bumpers would normally scrape the ground during steep departure and approach angles off-roading, off-roading bumpers will not.

Push bar(s)

Push bar

A metal bar(s) that's an extension to a grille guard or add-on to an off-road bumper designed to align with the bumper of another vehicle. Push bars allow you to use your vehicle to gently push another without causing damage because pressure is evenly applied. Horizontal push bars are often referred to as "pre-runner" bars.

Rocker Bars

Rocker Bars

Also known as "rocker guards", these bolt to the frame along the sides of your vehicle and serve to protect vulnerable rocker panel body pieces that can get damaged during off-roading.

Sand ladders

Sand Ladders

A form of traction aid consisting of a pair of ramps with perforations designed to increase tire grip. These ladders are placed beneath the wheels of a vehicle that has become stuck in muck or snow to provide a firm traction surface that would not otherwise exist.

Skid Plate

Skid Plate

A flat metal plate that bolts onto the frame of your car, grille guard, bull bar, or bumper. Offers protection for mechanicals behind it such as oil pans, differential, steering linkages, etc. that are particularly vulnerable when off-roading over uneven terrain.

Snatch-block

Snatch-Block

Pulley device that can be used in conjunction with a winch to vary the angle of pulling when necessary. Used properly, it can even double a winch cable's pulling power.

Spool out

To allow the winch cable to unwind off the drum after releasing the winch's drum brake.

Sport Bar

Sport Bar

A single tubular metal reinforcement bar designed to match the contours of an OEM bumper. Sport bars mount to steel framework under the vehicle rather than to the bumper itself. These offer minimal protection during off-roading, and are designed more for minor parking speed impacts.

Spring Rate

Spring Rate

As a pound-per-square-inch measurement, it's the force required to compress a coil spring 1 inch. The higher the per-inch spring rate, the stiffer the spring. Spring rate is also used to describe whether a spring has the same rate of compression at all points during its travel ("linear"), gets progressively stiffer the more it compresses ("progressive"), or be specially configured to change characteristics abruptly ("dual rate.)

Stinger Bar

Stinger Bar

A front-mounted assembly that's an extension to a grille guard, or an add-on to an off-road bumper. Stinger bars are angled upward at a steep rake to prevent your vehicle from tumbling off its wheels onto the front end should an end-over-end tumble become imminent down a steep descent. Stinger bars are also helpful in allowing you to slide out of a hole without burying your front end.

Suspension Travel

Suspension Travel

The amount of vertical wheel travel permitted by a vehicle's suspension. Greater suspension travel is a valued asset on uneven ground and rocky trails.

Stair-step

Stair-Step

In off-roading, a series of one or more ledges that must be climbed in succession. Stair steps are common on trails that follow creek beds.

Tow Bar

Tow Bar

For those that don't have a trailer, tow bars allow one vehicle to pull another one behind it with 4 wheels rolling on the ground. A single bar on one end connects to your tow hitch, then splits into two bars that attach to the frame (or D-ring hooks) of the vehicle being pulled.

Tow Hooks

Tow Hooks

Heavy-duty forged steel hooks bolted or welded to the front or rear of a vehicle frame that serve as attachment and pulling points for snatch-em straps and winch cables.

Track

Track

The distance between two wheels that are on the same axle, as measured from the centerpoints of left- and right-side wheels.

Trailer Winch

Trailer Winch

A smaller winch for lighter vehicles typically hauled on trailers such as ATVs, boats, or lightweight dune buggies. Trailer winches often have manual cranks with multiple gear sets, or they may be electric powered.

Tubular bar

Tubular bar

A round metal bar that's hollow inside. Tubular bars are used to form most grille guards, bull bars, stinger bars, and even tubular style off-road bumpers. They offer the advantage of very high strength for their weight.

Under-Axle Clearance

Under-Axle Clearance

Space between the ground and the lowest-lying part of a vehicle's axle, which is usually a center differential housing.

Wheel adapter

Wheel Adapter

Metal plate with wheel studs that allows a wheel with one bolt pattern to be used on a truck with a dissimilar bolt pattern. Useful for mounting larger wheels with bigger bolt patterns than your vehicle was equipped to handle originally.

Wheelbase

Wheelbase

Distance from the center of a vehicle's front wheel to the center of its rear wheel on the same side of the vehicle. Vehicles with longer wheelbases offer a smoother ride, but shorter wheelbases prove advantageous on uneven trails because the center of the vehicle is less likely to become stuck in a high-centered position.

Winch Gear Ratio

Winch Gear Ratio

On manual-crank winches (for trailers, etc.), this gear ratio number represents how many times a handle must be cranked to turn the winch drum one revolution. A ratio of 15:1 means the handle is cranked 15 times to complete one full revolution of the drum spool.

Winch Mount

Winch Mount

A specially-designed metal assembly that bolts to a bumper or frame, or slides into a receiver hitch, to provide the ability to properly support a winch.

Winch Pull Rating

Formula for determining the amount of weight a winch can safely pull on level ground without the help of a snatch block or other device. A generally accepted formula is to choose a winch that is rated for at least 1.5 times the weight you will need to pull. You will need to calculate the total weight of the running vehicle, not just the listed curb weight. This will include vehicle curb weight, occupant weight, equipment weight, accessory weight, and anything else inside your car or truck.

Winch Rated Line Speed

The length of line that a winch can spool off and on its drum in one minute. Faster line speeds provide quicker winch pulls and are generally found in more expensive winches.

Winch Remote Clutch Kit

Winch Remote Clutch Kit

During winching, this tool prevents a wire cable from becoming tangled when freespooling, and it assists in uniform spool up.

Off-roading is a fun, wholesome, outdoor activity. At the same time, it's not without its risks, and any off-roading adventure should be approached with full preparation and knowledge. Everyone is going to have their "first time" at the experience. We hope that this glossary of off-road terminology will add to the enjoyment you'll have "off the beaten path", whether it's your first, or your hundred-and-first time! Have fun, and be safe!

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