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Glossary A-M

4X4 / 4WD
Four Wheel Drive. A vehicle drivetrain that utilises a transfer case to distribute engine power between the front and rear axles in order to drive all four wheels.


Anti-locking braking system. Electronic system that detects when a wheel is about to lock up and releases the brake pressure automatically and momentarily to prevent lockup.
Air Compressor
A device that converts power (usually from an electric motor, battery, diesel engine or petrol engine) into potential energy by forcing air into a smaller volume and thus increasing its pressure. The energy in the compressed air can be stored while the air remains pressurised. The energy can be used for a variety of applications to operate a vehicles air lockers, inflate tyres or control an air suspension system.
Air Jack
Large strong inflatable bag which is placed under the chassis, which then connects to the exhaust pipe and is inflated by exhaust emmissions, lifting the vehicle. Used for vehicle recovery situations in mud, snow and sand.
Air Locker
A manually controlled, air operated locking differential which uses compressed air from an onboard compressor to lock and unlock the diff. Created to provide 100% traction on demand, without sacrificing any of your vehicle's highway driving performance.
Air Suspension and Air Bags
Airbags are used as springs for front-to-rear and side-to-side levelling control of a vehicle providing full adjustability when towing, off-road use or for passenger and cargo loading. enables a vehicle to level up when carrying heavy, uneven loads or when towing caravans, camper vans, boats and trailers. You can lower your vehicle for easy loading then raise again.
All Wheel Drive (AWD)
A drivetrain that employs a front, rear and center differential to provide power to all four wheels of a vehicle.
Describes the flexibility of an off-road vehicle's suspension. The more a wheel can travel or flex, the better it can maintain contact with the ground and provide the traction needed.
Aggregate Trailer Mass. The total laden weight of a trailer, which includes the tow ball mass and whatever you add as payload (eg. water, gas, luggage). The ATM is specified by the trailer manufacturer and must not be exceeded.
An all-terrain vehicle is defined as a motorised, off-highway vehicle designed to travel on four low-pressure tyres, having a seat designed to be straddled by the operator and handlebars for steering control. (also known as a quad, quad bike, three-wheeler, four-wheeler).
A shaft, rod or spindle (either fixed or rotating) passing through the centre of a wheel or group of wheels. Wheels can turn and rotate around the axle.


Ball Joints
Movable joints in the steering linkage and suspension system of a vehicle that permit rotating movement in any direction between the parts that are joined.
Bash Plate
Heavy duty steel plate bolted to a vehicle's under body to protect the vital areas and components (engine, driveline or transmission) from damage, usually associated with off-road vehicles.
The edge of the tyre that meets the rim of the wheel. Wheels are made with a small groove into which the tyre bead sits. When the tyre is properly inflated the air pressure within the tyre keeps the bead in this groove.
A device that secures the seal between the bead of the tyre to the rim so it does not separate when the tyre is run at low pressure.
Bio Diesel
An alternative fuel formulated exclusively for diesel engines. It's made from vegetable oil or animal fats. Biodiesel can be mixed with petroleum diesel in any percentage, from 1 to 99, which is represented by a number following a B. For example, B5 is 5 percent biodiesel with 95 percent petroleum, B20 is 20 percent biodiesel with 80 percent petroleum, or B100 is 100 percent biodiesel, no petroleum.
Body Lift
Remounting the vehicles body higher above the chassis than originally designed. This method is done to to run larger tyres on a vehicle. It involves installing spacers where the body mounts to the frame in order to increase the clearance between tyres and the body. Usually done in conjunction with a suspension lift.
Is the diameter measurement of the cylinders in a piston engine. Or diameter measurement of the cylinder in a shock absorber.
Is a device fitted to the front of a vehicle to protect its occupants from collisions, or protect the vehicle headlights, spotlights or radiator. Bullbars vary in size and form, and are usually made of welded steel or aluminium tubing. The "bull" in the name refers to cattle. (Also known as a roo bar, nudge bar, moose bumper, push bar, grill guard, brush guard).
Bump Steer
Is the vehicle steering off the intended track, on it's own (without driver input), when encountering a bump and is the result of poor suspension geometry.
These components protect the suspension and vehicle (as well as the occupants) from "bottoming out" the suspension, caused when an obstruction (or hard landing) causes the suspension to run out of upward travel without fully absorbing the energy of the stroke. Without bump-stops, a vehicle that "bottoms out" will experience a very hard shock when the suspension contacts the bottom of the frame or chassis body, which is transferred to the occupants and every part of the vehicle. Factory vehicles often come with plain rubber bumpstops while a high end Ultra4 race vehicle, will fit a hydraulic bumpstop.
Bushes, or bushings, act as bearings at suspension fulcrum points, to allow for movement of the component, while maintaining its alignment. They can be metallic, rubber, nylon, or polyurethane. A common application is in vehicle suspension systems, where a bushing separates the faces of two metal objects while allowing a certain amount of movement.


Cab Chassis
A ute supplied with no factory tray or flatbed, just the bare chassis on the back, also comes with the main body cab.
Camber is the angle of the wheel, measured in degrees, when viewed from the front of the vehicle. If the top of the wheel is leaning out from the center of the car, then the camber is positive, if it's leaning in, then the camber is negative. If the camber is out of adjustment, it will cause tyre wear on one side of the tyre's tread. If the camber is too far negative, for instance, then the tyre will wear on the inside of the tread. If the camber is different from side to side it can cause a pulling problem. The vehicle will pull to the side with the more positive camber. On many front-wheel-drive vehicles, camber is not adjustable. If the camber is out on these cars, it indicates that something is worn or bent, possibly from an accident and must be repaired or replaced. (See Wheel Alignment)
A camshaft is a rotating cylindrical shaft used to regulate the injection of vaporised fuel in an internal combustion engine. Camshafts are responsible for the accurately-timed fuel injections required by internal combustion engines. Camshafts have multiple cams on them, which are used to open valves through either direct contact or pushrods. A camshaft is directly coupled to the crankshaft, so that the valve openings are timed accordingly.
When you turn the steering wheel, the front wheels respond by turning on a pivot attached to the suspension system. Caster is the angle of this steering pivot, measured in degrees, when viewed from the side of the vehicle. If the top of the pivot is leaning toward the rear of the car, then the caster is positive, if it is leaning toward the front, it is negative. (See Wheel Alignment)
A vehicle frame, also known as its chassis, is the main supporting structure of a motor vehicle to which all other components are attached.
Is an automobile suspension device. Is short for "coil spring over shock". A shock absorber (damper) which is fitted inside a coil spring. The shock absorber and spring are usually assembled as a unit prior to installation.
Coil Bind
A condition where springs are compressed to the point that the coils touch.
Coil Spring
A mechanical device, which is typically used to store energy due to resilience and subsequently release it, to absorb shock, or to maintain a force between contacting surfaces. They are made of materials formed into the shape of a helix which returns to its natural length when unloaded. (also known as a helical spring)
Comp Truck
A 4x4 designed for offroad competition events such as offroad racing, winch challenges, rock crawling. Usually fitted out with superior heavy duty aftermarket parts and accessories.
Compression (Suspension)
When a car passes over a bump in the road, for example, the obstacle forces the wheel up into the wheel housing. In the process, the spring is compressed. The shock absorber is now in its compression stage.
A device which supplies compressed air. Often used for inflating tyres or airbag suspension. Also used for air lockers.
Constant 4WD
Is a system that powers all four wheels at all times and it can be used full time on all surfaces including high traction surfaces. Note that 2WD is not available. Driver has a choice of a "4-high" - 4H (that's your every day setting) and "4-low" - 4L. Full time 4WD vehicles work very well on-road and are very capable off-road.
Control Arm
Also known as the A-arm. These are part of the suspension system. These are main link between the vehicle frame and the wheels that acts as a hinge to allow the wheels to go up and down independently of the chassis.
Crew Cab
Is a vehicle which features seating for up to five or six people with a rear bench seat and two full-size front-hinged doors on both sides. Crew cabs are available in both long-bed and standard-bed length versions. (also known as a double cab or dual cab)
Cross Member
A crossmember is a structural section, usually of steel, usually boxed, that is bolted across the underside of a motor vehicle, to strengthen the chassis or support the engine and / or transmission. For the suspension of any car to operate as it should, and for proper handling, and to keep the body panels in alignment, the frame has to be strong enough to cope with the loads applied to it.
CV Joint
A constant velocity joint, is part of a drive shaft, the shaft that attaches to a car's transmission at one end and the wheel at the other. These joints are designed to be able to bend in any direction while continuing to turn the drive wheels at a constant velocity. They are primarily used in the drive shafts of front wheel drive cars.
Is the area or part of the engine in which the piston travels up and down.


A shock absorber that controls unwanted spring motion through a process known as dampening. Shock absorbers slow down and reduce the amount of motion by turning the kinetic energy of suspension movement into heat energy that can be dissipated through hydraulic fluid in the damper.
Deep Cycle Battery
A lead-acid battery designed to provide a steady amount of current over a long period of time. A deep cycle battery is also designed to be deeply discharged over and over again (something that would ruin a car battery very quickly).
Diff Breather
Vents the air pressure in drivetrain assemblies such as the differentials. Under normal operation, the diff heats up and the air inside expands, increasing the pressure and thus the need to be vented (to escape) otherwise it will force oil out of the diff. Therefore the diff has a vent or a breather. (When the diff cools down the air inside contracts and creates a vacuum.) There is an problem for water crossings. Once the diff gets put into water the cooling action rapidly cools the diff causing them to suck in air, but if under water all that can enter via the original diff plug is water or mud. By fitting the diff breather you will ensure that your diff cannot be damaged by water or mud entering it.
Diff Guard
Heavy duty steel plate fitted to a vehicle's under body to protect the differential housing from damage while driving off-road.
Diff Lock
Differential lock is a mechanism to prevent the differential from allowing its two output shafts to rotate at different speeds for when offroad. Used for better traction.
Differential (Diff)
A differential's purpose can be broken down into three functions. Firstly, a differential takes the power from the engine and connects it with the driving wheels. Secondly, a differental is the last gear reduction that will occur in the vehicle. Thirdly, the differential transmits the power from the engine to the wheels while allowing the wheels to rotate at different speeds.
Drag Link
A steering rod link that connects the pitman arm on the steering box to the wheel.
A sturdy metal tube with universal joints on either end that connects the engine to a differential on a rear-wheel or four-wheel drive vehicle.
Drivetrain / Driveline
The system of components (transmission, gearbox, differential, transfer case etc) that generates power and transmits it from the engine to a vehicles wheels.
Dual Cab
Is a vehicle which features seating for up to five or six people with a rear bench seat and two full-size front-hinged doors on both sides. Dual cabs are available in both long-bed and standard-bed length versions. (also known as a double cab or crew cab)


An abbreviation for Electronic Fuel Injection. This is a computer controlled fuel delivery system. As opposed to mechanical fuel delivery systems.
Electric Winch
Usually a 12V power-driven mechanical drum/spool having a wire cable or synthetic rope mounted to the front of the vehicle used to recover or haul vehicles out of mud, snow, water or hazards. You can either pull in (wind up) or let out (wind out).
Electronic Diff Lock
EDL permits smooth starts on split-friction road surfaces with differing levels of grip. If one wheel starts to spin, the electronic differential lock will brake the wheel as necessary, directing power to the wheel with better grip in the process. May be engaged as required by the vehicles computer or manually by the driver.
Exhaust Jack
A large inflateable heavy duty bag placed under the vehilce to jack it up using its own exhaust gas to inflate the air bag. A hose connects the jack to the exhaust pipe. Also known as an air jack.
Exhaust System
The tubing, mufflers and catalytic converters that direct exhaust gases from the engine to the atmosphere.
Extended Cab
Is a vehicle which features seating for up to four people with two main front seats the driver and passanger. Has rear jump seats behind the driver and passenger seats either for storage or to hold two passengers. Usually has one full-size front-hinged door on both sides. (also known as a extra cab).
Extra Cab
See Extended Cab


Fire Extinguisher
A device used to put out fires with the use of either water and foam or dry chemicals. Also known as a fire bottle.
An accessory such as a locknut, bushing, or other part of a wiring system that is intended primarily to perform a mechanical function.
Extended flares are fitted to wheel arch to cover extra large or wide tyres so the offroad vehicle remains legal. Sometimes called fender flares.
The distance a wheel can travel up and down relative to the vehicle body. Vehicles with a lot of flex can keep their wheels on the ground on uneven terrain.
Free Wheeling
The term used when the front wheel hubs are unlocked and the wheel spins due to momentum rather than power.
Free Wheeling Hubs
A vehicle device which allows you to disconnect the front axle assembly on part-time 4WD's. Also called locking hubs. The 4x4 can be switched from 2-wheel-drive mode ("2WD"), where only the rear wheels are driven by the drivetrain, to 4-wheel-drive mode ("4WD"), where all 4 wheels are driven by the drivetrain.
Fridge / Freezer
A portable 12V fridge or freezer combination carried in your 4x4. Capacity can vary between 30 litres up to 75 litres.
Fridge Slide
A base for your fridge mounted on roller arms allowing the fridge to slide in and out of the back of your offroad vehicle. For easy access. Also known as fridge drop slide.
Foam Cell Shock
A style of shock absorber with 2 separate compartments, one filled with oil and the other filled with foam instead of Nitrogen gas to compress the oil. The foam keeps pressure on the oil to prevent aeration.
Four Wheel Drive
A vehicle drivetrain that utilises a transfer case to distribute engine power between the front and rear axles in order to drive all four wheels. Also 4X4 and 4WD.
Front Wheel Drive
FWD is a 2 wheel vehicle system that transmits power through the front wheels instead of the rear wheels.
Any combustible liquid, such as petrol, that can be used to fuel an engine.
Full Coil Suspension
A vehicle suspension system where all four wheels have their own coil spring.


Gas Shock
A style of shock absorber with 2 separate compartments, one filled with oil and the other filled with Nitrogen gas to compress the oil. The Nitrogen gas keeps pressure on the oil to reduce the fluid from foaming. Also known as a Gas-Filled Shock Absorber.
An electro-mechanical process of coating Zinc to ferrous metals to reduce or prevent rust.
Gross Combined Mass GCM is the rating provided by the manufacturer of the tow vehicle. The maximum laden mass of a motor vehicle plus the maximum laden weight of an attached trailer is not permitted to exceed the GCM rating.
A glowplug (alternatively spelled as glow plug or glow-plug) is a heating device used to aid starting diesel engines.
A device that controls another device, usually on the basis of speed or rpms.
The Global Positioning System (GPS) is a space-based navigation system that provides location and time information in all weather conditions, anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites.
Variations of the Nissan Patrol Series.
Grey Nomad
The term used to describe the senior or older retired traveller who moves and travels from place to place like nomads but in a camper van, caravan or motor home.
Ground Clearance
The distance between the ground and the underside of the vehicle. Also known as the Ride Height or Clearance.
Gross Trailer Mass. The total permissible mass which includes whatever you add as payload (eg. water, gas and luggage) that can be supported by the wheels of a trailer. This does not include the mass supported by the tow ball.
Variations of the Nissan Patrol Series.
The Gross Vehicle Mass GVM is the maximum allowable total mass of a fully loaded motor vehicle, consisting of the tare mass (mass of the vehicle) plus the load (including passengers).
In relation to motorsport, a gymkhana is any event which is run on a course which has a starting point, a finish line and some "obstacles" to get through or go around, all within a certain time limit.


Hand Winch
A cost effective vehicle recovery winch operated manually by a person. Alternative to a vehicle electric winch.
Automobile handling and vehicle handling are descriptions of the vehicles ability to accelerate, brake, corner and manoeuvre with confidence, safety and precision.
Heavy Duty (HD)
A device or product that is designed for heavy use.
Heavy Duty Coil spring
Coil springs that have a larger wire diameter, and 3 to 5 percent greater load-carrying capability than standard coil springs.
Heim Joint
A rod end bearing, also known as a heim joint or rose joint, is a mechanical articulating joint. These joints are used on the ends of rod ends, steering links, tie rods, or anywhere a precision articulating joint is required. A ball swivel with an opening through which a bolt or other attaching hardware may pass is pressed into a circular casing with a threaded shaft attached.
Helper Springs
Extra springs added to the vehicle to help provide leveling control, improve stability and handling of the vehicle while carring load.
High Country
The High Country is located in the north-east of Victoria. It is an area that features national parks, Victoria's highest mountains, lakes, snow resorts, vineyards and a rich history including gold discovery, cattlemen and bushrangers.
High Lift Jack
Is jack capable of lifting the vehicle high off the ground and also can be used as a winch.


Independent Front Suspension is a suspension system that allows the two tyres on one axle housing to move separately from one another. The system supports the chassis on the wheels without the use of rigid axles where the movements of the two front wheels are inter-dependent of each other.
A power inverter is an electronic device for converting 12V DC (Direct Connect) power into 240V AC (Alternating Current) power.
IPX Ratings
In relation to liquids... the IPX standard gives you a clearer picture of how water resistant a Product (eg. Light) is, compared to vague marketing terms such as 'waterproof'. [In Detail - Classifies and rates the degree of protection provided against intrusion (body parts such as hands and fingers), dust, accidental contact, and water by mechanical casings and electrical enclosures - Solid or Liquids]


J Rim
A groove around the outer edge of a wheel rim to provide a lock for the tyre bead.
Jam Nut
A second nut tightened against a primary nut to prevent it from working loose. Used on inner and outer tie-rod adjustment nuts and on many pinion-bearing adjustment nuts.
Jerry Can
A metal or plastic container used for storing, transporting or carrying liquids usually extra fuel or water. The most common size is 20 Litres.
Jockey Wheel
A jockey wheel is a retractable adjustable-height wheel used on the front of trailers that supports the trailer and ads additional support when not connected to a tow bar. The trailer will remain level and can be easily moved around.
The inward reaction of the spring and shock absorber when a wheel hits an obstruction.
Jump Start
Using jumper cable leads to connect a fully charged battery to a dis-charged battery to start the vehicle.
Jumper Cables
Two heavy-duty cables used to connect two batteries, used for jump starting a vehicle.


Keyless Entry
A system using a coded keypad that allows the operator to unlock the doors or the trunk from outside the vehicle without the use of a key.
An abbreviation for the metric kilogram.
Is the main pivot in the steering mechanism of a car or other type of vehicle.
Kinetic Energy Recovery Rope
K.E.R.R. is a Recovery Rope that utilises KINETIC ENERGY. This is similar to a Snatch Strap.
An abbreviation for the metric kilometer.
An abbreviation for the metric kiloPascal.


Leaf Spring
A rear, vehicle-suspension spring featuring one or more flat leaves of spring steel with graduated lengths. It has an eye at one end to connect to the vehicle frame and it is connected to the axle with a U-bolt.
Light Emitting Diode - is a two-lead semiconductor light source. The semiconductor device emits visible light when an electric current passes through it.
Lift (Body Lift)
A body lift is simply polyurethane or aluminium blocks fitted inbetween the body mounts and the body cab. While the body itself is higher, the suspension and wheels remain at the original height.
Lift (Suspension Lift)
A suspension lift is a modification, often done to 4x4's to raise the ride height of the vehicle. Suspension lifts (also referred to as lift kits) enable steeper approach, departure, and breakover angles, higher ground clearance, and helps accommodate larger wheels and tyres.
Lift Block
Lift blocks are a reliable, inexpensive lift alternative for the rear of trucks with leaf spring suspension. The axle mounts under the spring and blocks placed between the axle and spring result in lift of an amount equal to the thickness of the block.
Any 4WD that is raised either by a suspension or body lift.
Limited Slip Differential
A limited-slip differential prevents excessive power from being allocated to one wheel, and thereby keeping both wheels in powered rotation. Used to prevent wheelspin on slippery surfaces and to ensure that the engine's power is transmitted equally between the two tyres.
The exact path a vehicle will take while driving over or through an obstacle when driving offroad.
Linear Springs / Linear Spring Rate
These are coil springs that have a spring rate consistant along the entire length with the compression of the spring. The amount of space between every winding or coil of the spring is the same.
A mechanical device in either the front or rear differential that sends engine power to both wheels regardless of traction. A locking differential is designed to overcome the chief limitation of a standard open differential by essentially "locking" both wheels on an axle together as if on a common shaft. This forces both wheels to turn in unison, regardless of the traction (or lack thereof) available.
Long Range Tank
A relacement fuel tank or additional fuel tank that provides a vehicle with a longer range or distance it can travel without needing to refuel.
A trade name for a product line of sealants and adhesives that are used in the automotive industry.
Liquid Petroleum Gas.
Limited Slip Differential.
Long Wheel Base.
Lower Control Arm
These are part of the suspension system. These are main link between the vehicle frame and the wheels that acts as a hinge to allow the wheels to go up and down independently of the chassis.


Mandrel Bent Exhaust
Bending a exhaust pipe in such a way with the use of dies and mandrels so that the pipe diameter does not change. This improves airflow.
MacPherson Strut
A type of front suspension having a shock absorber mounted directly below the coil spring.
MacPherson Strut Suspension
A front-end, independent suspension system in which the combined strut, steering knuckle, and spindle unit, supported by the coil spring at the top, is connected from the steering knuckle to an upper-strut mount.
To alter or change from the original. Either a part that has been replaced with a different part or an actual update to the existing part.
Monotube Shock Absorber
A shock absorber where the piston rod assembly runs in a single wall tube. In mono tubes the gas is usually housed within the main cylinder and generally separated from the main chamber by a floating piston.
MIG Welding
A term used for metal inert gas welding.
A device in the exhaust system used to reduce noise.
Model Year
The year of vehicle manufacture, as designated by the manufacturer.
Monster Truck
A truck, usually a pick-up, having huge, oversized wheels and tyres with a heavy duty power train to drive them.
Motor Oil
A lubricant designed and formulated for use in an engine.