Glossary N-Z

N

Negative Camber: The inward vertical tilt of the wheels on a vehicle.
Nitrogen: A colorless, odorless, tasteless gas.
Nitrogen Shocks: 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 gas keeps pressure on the oil to prevent aeration.
Nudge Bar: A front nudge bar provides increased frontal protection and adds to the aesthetic appeal of your vehicle. Nudge bars also serve as an ideal platform for mounting accessories such as driving lights and CB antennas.
Nut: A fastener having internal threads used on a bolt to secure two or more pieces together.

O

Odometer: A mechanical or electronic counter in the speedometer that indicates trip or total kilometres or miles driven on the vehicle.
OEM: An abbreviation for original equipment manufacturer.
Off-Road: Any unmade, unpaved, rough, or ungraded terrain on which off-road activities take place.
Off-Road Vehicle: Any vehicle designed for use in off-road activities.
Oil: A liquid lubricant used to reduce friction between moving parts.
On-Road: Refers to paved or smooth-graded surface terrain on which a vehicle can operate normally.
OHC: An abbreviation for overhead cam or overhead camshaft.
Overhead Cam / Overhead Camshaft: An engine in which the camshaft is mounted over the cylinder head. Usually a single or double overhead cam. DOHC - Double Overhead Camshaft has 2 camshafts above the cylinders. SOHC - Single Overhead Camshaft mounted above the cylinders.
Open Differential: This is a normal differential rather than a locked or limited slip.
Oversteer: Is what occurs when a vehicle turns (steers) by more than the amount desired by the driver.

P

Panhard Rod: A rod that is attached to the vehicle frame at one end and to the axle at the other end to prevent the chassis from moving side to side relative to the axle.
Part Time 4WD: Four wheel drives that run in 2WD on normal roads and surfaces and switch to 4WD offroad.
Pinion: Is usually a small round gear used in various applications such as the smallest gear in the drive train or small ring gear such as at the end of the steering shaft of a rack-and-pinion steering system.
Pipe: An exhaust system.
Piston (Engine): An engine part that moves up and down in the cylinder and transfers the force of the expanding gases via the piston pin and connecting rod to the crankshaft.
Piston Rod: A plated rod attached to the shock-absorber piston, usually extending from the top of the shock to provide an attachment point to mount on the vehicle.
Pitman Arm: Is the steering box transfer linkage in a Pitman type vehicle steering mechanism. It is the component in the system which translates the radial motion of the steering column or shaft into the linear motion to turn the wheels.
Pumpkin: The centre section of the axle housing that contains the differential carrier and gear set.
Power Steering: A power assisted steering system that uses hydraulic pressure to increase the torque (turning effort) applied to the steering system by the driver.
Power Train: The system of components (transmission, gearbox, differential, transfer case etc) that generates power and transmits it from the engine to a vehicles wheels. Also known as drive train.
PSI: An abbreviation for pounds per square inch. The unit of measure for tyre pressure.

Q

Quad: A four-wheel drive vehicle.

R

R&D: An abbreviation for research and development.
Rack and Pinion: A type of steering assembly that has a gear or pinion at one end of the steering shaft engaging a horizontal-toothed bar or rack having tie rods at either end that are attached to the steering arms.
Radius Arms: A radius arm (also called a radius rod or a torque arm) is a suspension link system intended to control wheel motion in the longitudinal direction. The link is connected (with a rubber or solid bushing) on one end to the wheel carrier or axle, on the other to the chassis of the vehicle.
Ramp Angle: Also known as breakover angle. This is the measurement given to the maximum possible angle (expressed in degrees) that a vehicle, with at least one forward wheel and one rear wheel, can drive over without the apex of that angle touching any point of the vehicle other than the wheels. This definition is based upon the wheels being in continuous contact with the surface.
Rattle Gun: Also known as an impact wrench. A socket wrench power tool designed to deliver high torque output by storing energy in a rotating mass, then delivering it suddenly to the output shaft.
Rebound: The outward extension of the springs and shocks in a vehicle suspension system. After a suspension spring or shock is compressed the spring or shock will return to its previous length.
Recovery Gear: Specialised tools and equipment designed to recover vehicles that are stuck or can't make any progress.
Recovery Point: A hook or point on a vehicle which is designed to be used for recovering vehicles.
Rear Control Arm: Horizontal arms that connect the rear axle housing to the frame when coil springs are used in the rear suspension system to maintain axle alignment and handle the driving and torque loads.
Rear Leaf Spring: A term used for leaf springs.
Rear Shock: A type of shock absorber that is on the rear of the vehicle and compatible with a particular type of driving and its load requirements.
Rear Suspension: An integral part of the total suspension system designed to keep the rear axle and wheels in their proper position under the car body.
Rear-Axle Assembly: A group of parts that operate to transfer driving torque from the drive shaft to the rear wheels.
Rear-Axle Housing: The basic framework of the rear-axle assembly inside which the individual parts, including the differential and axles are mounted and/or operate.
Rear Wheel Drive: A drivetrain layout that provides power to the rear wheels only. Often referred to an rear drive.
Rebound Travel: The downward movement of a wheel from its normal position when the spring and shock are expanding, as the sudden drop of a wheel into a depression and a weight transfer away from the wheel.
Recreational Vehicle: A RV is a motor-driven, van-like vehicle having sleeping, food preparation and bathroom facilities.
Research and Development (R&D): To research and develop a concept, idea, system or product.
Remote Reservoir Shock Absorber: Are designed with an external reservoir that increases fluid capacity. This increase in capacity helps lower fluid temperature, thus offering the ability to ride over rough terrain without experiencing shock fade.
Ride and Handling: A measure of the vehicle comfort levels for the driver and passengers (in relation to suspension and tyres) and responsiveness in relation to the driver's steering actions.
Ride Height: The distance between the road and the bottom of a vehicle.
Rigid Axle Suspension: A term used for solid-axle suspension.
Ring and Pinion: The combination of a ring gear attached to the differential and the pinion at the end of the drive shaft.
Rock Crawling: Driving vehicles over extremely rocky terrain usually in highly modified four wheel drive vehicles such as trucks, jeeps and buggies. Rock crawling is about slow-speed, careful and precise driving, and high torque generated through large gear reductions in the vehicles drivetrain.
Rock Slider: Heavy duty metal steel or tubing that runs along the sills of a vehicle to protect it from damage as it slides over rocks or when crossing large obstacles.
Rod: A steering arm. A suspension arm.
Roll Bar: A tubular bar behind the cockpit of a race car to protect the driver in case of a rollover.
Roll Cage: A tubular, cage-like structure surrounding the cockpit of a race car to protect the driver in the case of a rollover and to add strength to the overall structure of the vehicle.
Rollover: An accident in which the vehicle rolls over and over or turns upside down.
Roof Rack: A solid framework system for securely carrying and storing containers, luggage, sports gear, equipment or tools on the roof of a vehicle.
Roof Top Tent: A tent which has been designed to be carried on and setup from the roof of a 4WD vehicle.
RTC: Return To Centre Steering Damper.
RWD: Rear Wheel Drive.
Rzeppa Joint: A constant velocity (CV) universal joint.

S

SAS: Solid Axle Swap or conversion. The conversion of an Independant Front Suspension (IFS) vehicle to a solid beam axle.
SatNav: A satellite navigation or satnav system is a system of satellites that provide autonomous geo-spatial positioning with global coverage. It allows small electronic receivers to determine their location using time signals transmitted along a line of sight by radio from satellites.
SatPhone: A satellite phone or satphone is a mobile phone that sends and receives calls using satellites rather than landlines or cellular broadcasting towers.
Schrader Valve: The Schrader valve (also called American valve) is a type of pneumatic tyre valve used on virtually every motor vehicle in the world today. The Schrader valve consists of a valve stem into which a valve core is threaded. The valve core is a poppet valve (mushroom valve) assisted by a spring.
Shackle (U, D or Bow): A metal link (in the shape of a U, D or Bow) secured with a pin or bolt across the opening, used to join recovery gear together such as chain or rope together to perform a vehicle recovery. Also known as a threaded shackle.
Shackle (Greaseable): A small, swing-arm attachment at the rear of the leaf spring to allow the spring to flex.
Shackle Bushing: Insulated bushings to help prevent the transfer of noise, vibration and road shock from the suspension to the chassis and vehicle interior.
Shocks: A term used for shock absorber.
Shock Absorber: A hydraulic device used at each wheel of the suspension system to help control the up, down, and rolling motion of a car body by dampening the oscillations or jounce of the springs when the car goes over bumps. Also called shocks.
Shock Absorber - Adjustable: Shocks which are designed to be adjustable. You can change the dampening qualities - soft or hard.
Shock Absorber - Rebuildable: Shocks which are designed to be rebuilt when worn out. Can also be retuned.
Shock Compression: The shock absorber in its shortened position, which occurs when the wheel moves upward.
Shock Fluid: Specially formulated hydraulic fluid used inside of shock absorbers.
Shock Foaming: The mixing of air and shock fluid, due to rapid movement of fluid between the chambers, causing the shock absorber to develop a lag because the piston is moving through an air pocket that offers up resistance. A gas-filled shock absorber is designed to reduce oil foaming.
Shock Rebound: The rebound travel when the shock absorber is in its lengthened position, which occurs when the suspension or spring moves downward.
Side Step: A long metal or plastic step on the sills of a vehicle designed to help people get in and out of the vehicle. Not designed to protect the side of the vehicle unless it is a rock slider.
Single Cab: Is a vehicle which features seating for up to 2 people with only front seats, the driver and passanger. Has small space behind the driver and passenger seats for storage. Has one full-size front-hinged door on both sides.
Shim: Generally a shim is a washer or thin strip of material used to align parts, make them fit, or reduce wear. In relation to Shocks, shims are used to restrict oil flowing through the holes or ports in a piston. Shims are configured in various diameters and thickness to achieve specific results as a "shim stack".
Skid Plate: A heavy duty shield under the power train of an off-road vehicle to protect the engine and transmission. Also called a bash plate or underbody guard.
Skins: Tyres
Snatch Block: A snatch block is essentially a pulley inside a metal casing that is meant to help when winching and recovering vehicles. Using a snatch block greatly increases the pulling power of a winch.
Snatch Strap: A snatch strap is a piece of equipment used to help in the recovery of vehicles bogged in sand or mud or in a hazardous situation. Snatch straps are manufactured from webbing that is capable of approximately 20% stretch under load. This stretching property allows the strap to store kinetic energy, which is used to pull vehicles from a bog.
Snatch Recovery: Extracting a bogged / stuck vehicle using a snatch strap.
Snorkel: A Snorkel is a long narrow tube attached to the vehicle which moves the engine air intake from under your bonnet, to roof height. This raises the level of the air intake to reduce the chance of water entering your engine when crossing water. Also the higher air intake will reduce the amount of dust entering the system.
Solid Axle: A term used for beam axle or rigid axle.
Solid-Axle Suspension: Suspension system in which the wheels are mounted at each end of a solid, or undivided, axle or axle housing.
Spacer: Usually a device, such as a shim or washer, that is used to increase the space between two mating surfaces or parts. Also refers to plates designed to change the offset of a wheel.
Spring - Coil: 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)
Spring - Leaf: 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.
Spring Bind: A term used for coil bind.
Spring Leaf: A long, flat section of spring steel making up all or part of a leaf spring.
Spring Load: A measure, in pounds or kilograms, of how much weight a spring can support, generally at the installed height.
Spring Sag: The loss of spring load due to overloading and/or metal fatigue.
Spring Shackle: A small, swing-arm attachment at the rear of the leaf spring to allow the spring to flex.
Spring Over Axle (SOA): This is when the axle is underneath the leaf spring. This is done to improve clearance. SUA is spring under axle.
Spring Rate: The relationship of spring deflection to load applied, such as the amount of weight, in pounds per inch or newtons per millimeter, required to deflect the rear spring.
Steering Arm: An arm that is attached to the steering knuckle that turns the knuckle and wheel for steering.
Steering Damper: A steering damper, or steering stabiliser is a shock absorber or damping device designed to inhibit an undesirable, uncontrolled movement or oscillation of a vehicle steering mechanism. Mounted horizontally from the tie rod to the vehicle's frame or chassis. Also used to eliminate much of the steering vibration and wandering characteristics of over-sized tyres. Steering dampers reduce unwanted vibration and feedback through steering systems in rough conditions and improve steering control of your vehicle.
Stock: The term used to describe a factory-manufactured vehicle having standard design, parts, and color straight out of the showroom.
Suspension: The system that supports the weight of the vehicle and provides for a comfortable and safe ride for the driver and passengers.
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.
Suspension System: Components that support the total vehicle, including tyres, front and rear suspensions, springs, shock absorbers, torsion bars, axles, control arms and connecting linkages.
Suspension Travel: The distance a wheel can travel up and down relative to the vehicle body. Vehicles with a log of flex can keep their wheels on the ground on uneven terrain.
SUV: Sport Utility Vehicle.
Sway Bar: A metal bar on the suspension system that connects the two sides together. It is designed so that during cornering, it will reduce body roll. It will however reduce axle flex which is why you would have swaybar disconnects.
Sway Bar Disconnect: A system of disconnecting a swaybar for serious offroad use.
SWB: Short Wheel Base.
Synthetic Rope: Winch rope not made of metal but made of synthetic fibre. These are much lighter, stronger and safer than wire rope.

T

TD: Turbo Diesel
The Cape: Cape York of Australia.
Third Member: A differential.
Tie Down Point: A metal bracket which fits to the vehicle that is designed to tie down load on a vehicle. Not to be used as a recovery point.
Tie Rod: A heavy duty metal rod / linkage between the idler arm or pitman arm and the steering arm.
Tie-Rod End: A pivoting ball-and-socket joint located near the outer end of the tie rod used to connect the tie rods to the center link and to the steering arms.
Toe In: The amount by which the front of a front wheel points inward.
Toe Out: The amount by which the front of a front wheel points outward.
Torque: The measure of a force-producing tension and rotation around an axis.
Torsion Bar: A long, spring-steel bar replacing the coil springs, connected from the chassis to the lower control arm, to provide the necessary springing effect on the front suspensions by twisting rather than compressing or bending.
Towing Mirrors: Tow mirrors extend outward further than a standard vehicle mirror, which dramatically increases the driver's rearward vision. You simply pull outwards on the mirror head and it will slide out an additional length, allowing you to see down the side of your trailer, caravan, motorhome, boat etc.
Tranny: A term for transmission.
Transmission: A gearing device of a vehicle that provides variable ratios between the engine output and the differential input.
Transfer Case: A small transmission used on four-wheel-drive vehicles to transfer engine torque to the front and/or rear axles.
Travel: See Suspension Travel.
Tree Trunk Protector: Short strap designed to wrap around a tree so it may be used as a winching point. Can also be used to extend winch cables.
Turbo Charger: Is a turbine-driven forced induction device that increases an internal combustion engine's efficiency and power output by forcing extra air into the combustion chamber. A turbocharger is powered by a turbine driven by the engine's exhaust gas.
Turbo Diesel: A Diesel engine that is turbo charged and fitted with a turbo charger.
Twin Tube Shock: A shock absorber designed with two tubes - an outer and inner. The inner tube known as the working or pressure tube and an outer tube known as the reserve tube. The outer tube is used to store excess hydraulic fluid.
Tyre: Is a ring-shaped vehicle component that covers the wheel's rim to protect it and enable better vehicle performance. Most tyres provide traction between the vehicle and the road while providing a flexible cushion that absorbs shock.
Tyre Pressure: The pressure of air (or other gas) in the tyres. The more air inside gives the tyre a higher pressure. Usually measureed in Pounds Per Square Inch (PSI).

U

UHF: Ultra High Frequency (UHF) is the International Telecommunication Union (ITU) designation for radio frequencies in the range between 300 MHz and 3 GHz.
UHF Radio: In relation to 4WD use is a two way radio that uses the Ultra High Frequency.
Undercarriage: The chassis of a vehicle.
Understeer: Is what occurs when a vehicle steers less than the amount required by the driver. The vehicle runs wide around corners and does not corner as tightly as the driver would like when the steering wheel is turned.
Universal Joint: A universal joint, (U-Joint) is a joint or coupling in a rigid rod that allows the rod to 'bend' in any direction, and is commonly used in shafts that transmit rotary motion. It consists of a pair of hinges located close together, oriented at 90° to each other, connected by a cross shaft.
Upper 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.
Underbody Guard: Heavy duty steel plate bolted to a vehicle's under body to protect the vital areas and components (engine, driveline, differential, transmission etc) from damage, usually associated with off-road vehicles.
Ute: The term used to describe a utility vehicle. Ute is a term used originally in Australia and New Zealand to describe passenger vehicles with a cargo tray in the rear.

V

V6, V8: An engine having two banks of cylinders each set at an angle to form a V. V6 has six cylinders. V8 has eight cylinders.
Variable Springs / Variable Spring Rate: These are coil springs that have a spring rate increases or changes along the entire length with the compression of the spring. The amount of space between every winding or coil of the spring is different.
Vehicle: A generic term for a car, suv, 4wd, motorbike, truck etc. A means of transport, sometimes motorised, that moves on wheels, runners or tracks.
Vehicle Identification Number: The vehicle's identification number, located on the vehicle, which includes data such as the model of the vehicle, year, body, style, engine type and serial number.
VIN: An abbreviation for vehicle identification number.
Volt: A unit of measure of electrical force required to produce a current of one ampere through a resistance of one ohm. (One volt is defined as the difference in electric potential between two points of a conducting wire when an electric current of one ampere dissipates one watt of power between those points.)

W

Waterproof: The ability of an object to be submerged in liquids. As outlined in the IPX Ratings. Describes objects relatively unaffected by water or resisting the ingress of liquid under specified conditions. Such items may be used in wet environments or under water to specified depths.
Waterproofing: Waterproofing describes making an object waterproof or water-resistant.
Water Resistant: The ability of an object to be splashed with liquids. As outlined in the IPX Ratings. Describes objects relatively unaffected by water or resisting the ingress of liquid under specified conditions. Such items may be used in wet environments. But can't be submerged. Not the same as waterproof.
Watt: A unit of measure of electrical power. The unit is defined as joule per second and can be used to express the rate of energy conversion or transfer with respect to time.
Welding: Welding is the process of joining metals by melting the parts and then using a filler to form a joint. It can be done using different energy sources, from a gas flame or electric arc to a laser or ultrasound.
Wheel: A wheel is a circular component that is intended to rotate on an axle bearing. Wheels, in conjunction with axles, allow heavy objects to be moved easily facilitating movement or transportation while supporting a load, or performing labor in machines. In relation to a 4WD the wheel is a circular rim and hub to which a tyre is attached.
Wheel Alignment: Wheel alignment consists of adjusting the angles of the wheels so that they are perpendicular to the ground and parallel to each other.
Wheel Balance: Describes the distribution of mass on a vehicles tyre or the entire wheel (including the rim) to which it is attached. You will want an equal distribution of weight and even rotation of a wheel with a mounted tyre.
Wheel Rim: The wheel rim is the outer edge of a wheel, holding the tyre. Circular steel, aluminum, or magnesium components on which the tyres are mounted.
Wheel Travel: The distance a wheel can travel up and down relative to the vehicle body. Vehicles with a log of flex can keep their wheels on the ground on uneven terrain.
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).

X

X Chassis / X Frame: A conventional chassis design, used until the late 1960s, which narrows in the center, giving the vehicle a rigid structure that is designed to withstand a high degree of twist having a heavy front cross member to support the upper and lower suspension control arms and coil springs.
X Member (Cross Member): A X Member is a structural section, usually of steel, usually x shaped, that is bolted across the underside of a motor vehicle, to strengthen the chassis or support the engine and / or transmission.