An articulated hauler is a type of dump truck

Dump truck

A dump truck is a truck used for transporting loose material for construction. A typical dump truck is equipped with a hydraulically operated open-box bed hinged at the rear, the front of which can be lifted up to allow the contents to be deposited on the ground behind the truck at the site of...

 used to transport loads over rough terrain

Terrain

Terrain, or land relief, is the vertical and horizontal dimension of land surface. When relief is described underwater, the term bathymetry is used...

. The vehicle usually have all-wheel drive and consists of two basic units, one generally called the tractor and the rear section, called the hauler or trailer section, which contains the dump body. Steering is made by pivoting the front in relation to the back by hydraulic rams. This way the all wheel follow the same path, making it an excellent off-road vehicle

Off-road vehicle

An off-road vehicle is considered to be any type of vehicle which is capable of driving on and off paved or gravel surface. It is generally characterized by having large tires with deep, open treads, a flexible suspension, or even caterpillar tracks...

.

Manufacturers include Caterpillar

Caterpillar Inc.

Caterpillar Inc. , also known as "CAT", designs, manufactures, markets and sells machinery and engines and sells financial products and insurance to customers via a worldwide dealer network. Caterpillar is the world's largest manufacturer of construction and mining equipment, diesel and natural gas...

, Terex

Terex

Terex Corporation is an American-based diversified global manufacturer of a broad range of heavy equipment for a variety of industries, including construction, infrastructure, quarrying, recycling, surface mining, shipping, transportation, refining, utility and maintenance...

, John Deere

John Deere

John Deere was an American blacksmith and manufacturer who founded Deere & Company, one of the largest and leading agricultural and construction equipment manufacturers in the world...

/Bell Equipment, Moxy

Moxy Engineering

Moxy Engineering is a Norwegian manufacturer of articulated haulers for off-road use in the earth moving and construction industries. Moxy was founded by the industrialist Birger Hatlebakk, who had previously founded the Glamox factory in Molde.- History :Moxy built the first prototype dump truck...

/Doosan

Doosan Group

Doosan Group is a South Korean conglomerate quoted on the Korea Stock Exchange. Doosan has been placed 471st in the Fortune 2009. It has been included in the Forbes Global 2000 companies from 2007. It had recently acquired SKODA power thus making it a full swing in power plant global competitors...

 and Volvo CE

Volvo Construction Equipment

Volvo Construction Equipment is a subsidiary and business area of AB Volvo. Volvo Construction Equipment develops, manufactures and markets equipment for the construction and related industries.- Overview :...

. With half of global sales Volvo is the market leader in the segment, also being the vehicles prime pioneer enabling its introduction to the markets in 1966.

Although first envisioned as a soil and aggregate transporter (dumper), the chassis have since been used for many other applications. Ranging from concrete mixer

Concrete mixer

A concrete mixer is a device that homogeneously combines cement, aggregate such as sand or gravel, and water to form concrete. A typical concrete mixer uses a revolving drum to mix the components...

, water tanker

Tank truck

A tank truck or road tanker is a motor vehicle designed to carry liquefied loads, dry bulk cargo or gases on roads. The largest such vehicles are similar to railroad tank cars which are also designed to carry liquefied loads...

 and container truck

Intermodal container

An intermodal container is a standardized reusable steel box used for the safe, efficient and secure storage and movement of materials and products within a global containerized intermodal freight transport system...

, over to up-size off-road semi-trailer

Semi-trailer

A semi-trailer is a trailer without a front axle. A large proportion of its weight is supported by a road tractor, a detachable front axle assembly known as a dolly, or the tail of another trailer...

 hauler, hook loader

Hydraulic hooklift hoist

Hydraulic hooklift hoists are mounted on heavy duty trucks to enable hauliers to change out flatbeds, dumpster bodies, and similar containers. Primarily used in conjunction with tilt frame bodies and specialised containers, generally designed for the transportation of materials in the waste,...

 or crane

Mobile crane

-Defination:Mobile Crane A cable-controlled crane mounted on crawlers or rubber-tired carriers. A hydraulic-powered crane with a telescoping boom mounted on truck-type carriers or as self-propelled models..-History:...

, as well as used to tansport timber

Forwarder

A forwarder is a forestry vehicle that carries felled logs from the stump to a roadside landing. Unlike a skidder, a forwarder carries logs clear of the ground, which can reduce soil impacts but tends to limit the size of the logs it can move...

 and as a woodchipper

Woodchipper

A tree chipper or wood chipper is a machine used for reducing wood into smaller parts, such as wood chips or sawdust. They are often portable, being mounted on wheels on frames suitable for towing behind a truck or van. Power is generally provided by an internal combustion engine from to...

 platform. Its chassis have also been used for military purposes

Military vehicle

A military vehicle is a vehicle that includes all land combat and transportation vehicles, which are designed for or are in significant use by military forces throughout the world. Vehicles that are armored or intended for combat are often referred to as armoured fighting vehicles....

 given that it only is surpaced by tracked vehicle

Tracked vehicle

A tracked vehicle is a vehicle that runs on continuous tracks instead of wheels...

s in off-road capabilities. An example is the Archer Artillery System

ARCHER Artillery System

The Archer Artillery System or Archer - FH77BW L52 is an international project aimed at developing a next-generation self-propelled artillery system for Sweden and Norway...

.

History

In 1955 the Swedish company tractor trailer manufacturer Lihnells Vagn AB (Livab) started to develop a specialized dump vehicle in cooperation with Volvo's tractor subsidiary Volvo BM (the future Volvo CE). This was essentially a trailer with a powered axle mated to a agricultural tractor and utilizing its power take-off

Power take-off

A power take-off or power takeoff is a splined driveshaft, usually on a tractor or truck, that can be used to provide power to an attachment or separate machine. It is designed to be easily connected and disconnected...

 shaft to drive the trailer's axle. These were not articulated haulers in the modern sense, as the tractor retained its front axle to provide steering.

As the company's cooperation with Volvo BM deepened, it started experimenting with getting rid of the front axle by permanently attaching the trailer and instead provide steering through hydraulic cylinders forcing the trailer and wagon to turn in relation to each other. This was made in analogue with systems already developed for use in tandem tractors (see for example Doe Triple-D

Doe Triple-D

The Doe Triple-D or Doe Dual Drive is a make of tractor produced by Ernest Doe & Sons in the 1950s and 1960s in Ulting Essex. Its two engines and 90-degree articulation made it one of the most unorthodox tractors ever built.-Development:...

). The first purpose built articulated hauler was DR 631, a 4x4, released in 1966 with a larger 6x6 model DR 860 being released in 1968. In 1974 Livab was absorbed into Volvo BM.

Meanwhile a very similar vehicle was developed by another Swedish company, Kockum Landsverk AB. Having a similar tractor derived design it released its first articulated 4x4 dumper truck in 1967 named KL 411 that was replaced by a similar sized 6x6 in 1973 named KL 412. This company competed with Volvo BM until 1982 when it was bought by its bigger competitor.

The early articulated haulers were rugged, lacked suspension and had manual transmissions. This made them uncomfortable, noisy and demanding to drive and contributed to operator fatigue. The lack of suspension, other than that inherent in the large tires, also put stress on the drive-train and chassis, making them unsuitable for high-speed operation and in need of frequent service. The top speed was a mere 30 km/h. Many of these concerns have been eliminated with development over the years. The driver situation was addressed with the introduction of front suspension in the Volvo BM 5350 of 1979. This model also saw the introduction of automatic transmission and instead of a tractor derived cab, a new purpose designed cab.

Since there have been developments in brakes, differentials and other aspects of the drive-train to increase speed, usability and reliability. Full suspension came with the 2007 Volvo CE A35E/A40E.

Design

Retained features from its agricultural tractor

Tractor

A tractor is a vehicle specifically designed to deliver a high tractive effort at slow speeds, for the purposes of hauling a trailer or machinery used in agriculture or construction...

 heritage is the operators location and the basic layout. The driver thus sit behind the engine and above the transmission and front drive axle. The permanently attached trailer can not move vertically in relation to the tractor, but can rotate and swing on the horizontal plane. The operator have a conventional steering wheel that initiates hydraulic cylinder

Hydraulic cylinder

A Hydraulic cylinder is a mechanical actuator that is used to give a unidirectional force through a unidirectional stroke. It has many applications, notably in engineering vehicles.- Operation :...

s that push and pull the tractor relative to the trailer. The tractor and the trailer sections can move at great angles to each other making for a small turning radius.

The trailer axle(s) are driven by an drive shaft exiting the rear of the transmission with splines

Rotating spline

Splines are ridges or teethon a drive shaft that mesh with grooves in a mating piece and transfer torque to it, maintaining the angular correspondence between them....

 and universal joint

Universal joint

A universal joint, universal coupling, U joint, Cardan joint, Hardy-Spicer joint, or Hooke's 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...

s to accommodate the movements between them. All axles are portals with hub reduction and locking differential

Locking differential

A locking differential, diff-lock or locker is a variation on the standard automotive differential. A locking differential may provide increased traction compared to a standard, or "open" differential by restricting each of the two wheels on an axle to the same rotational speed without regard to...

s. Initially the axel diffs where permanently locked but recently some models can run with open but lockable differentials for better high-speed capabilities. The usual twin back axles are combined in a separate frame that is can pivot in relation to the trailer frame, keeping all wheels on the ground, but until recently always unsprung. Likewise the occasional single back axle usually are unsprung, while the front axle have suspension to give the operator a better ride. The reinforced cab is sometimes also sprung, as is done in modern cab-over-engine trucks, as is the drivers seat.

By the way the sections can twist in relation to each other and the way the vechicle steers, making the back tires follow the same path as the front tires, provide for excellent off-road capabilities in combination with all-wheel drive. The top speed is limited at 55–60 km/h and the net loading capacity is ranging from just below 25 to a little over 40 tonnes.

Comparison to rigid dump trucks

Articulated haulers excel in hauling material over rough terrain. They are rugged and are built to handle great inclines and slippery conditions. This is their main advantage over rigid haulers, which excel in carrying capacity. Where a articulated hauler can take no more than 40 metric tonnes there are models of rigid haulers (haulers with conventional front steering and rear-wheel drive) that can carry up to 400 tonnes.

This is also seen in the way they are used. Whereas rigid haulers find their best usage is at large surface mines and big quarries, where there is abundant space and hard level surfaces to drive on, articulated haulers are best used at rugged and cramped sites, such as large construction sites.

The articulated haulers relatively small size also make them able to drive on public roads between different worksites at a large construction project--something that is impossible for the largest haul trucks, which might even have to be disassembled to be moved between different locations. For transportation between different construction projects, articulated haulers usually have to be hauled on flatbed trailers as oversize cargo due to their width and weight, as well as their limited speed.

See also

• Volvo Construction Equipment
  Volvo Construction Equipment
  Volvo Construction Equipment is a subsidiary and business area of AB Volvo. Volvo Construction Equipment develops, manufactures and markets equipment for the construction and related industries.- Overview :...
  
  
• Dump trucks
• Gama Goat
  Gama Goat
  The Gama Goat was a six-wheel-drive semi-amphibious off-road vehicle originally developed for use by the US Military for the War in Vietnam. It was famous for an articulated body, which allowed it to travel over exceptionally rough terrain and for a unique four-wheel steering arrangement with the...
  
  
• Archer Artillery System
  ARCHER Artillery System
  The Archer Artillery System or Archer - FH77BW L52 is an international project aimed at developing a next-generation self-propelled artillery system for Sweden and Norway...