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Wheel loader

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Wheel loader (Liebherr L 556 2plus2), 17.3 t zgM

Wheel loader (Caterpillar 950K) on Pikes Peak Highway

Massey Ferguson MF 77 on a 180-Pf stamp of the definitive stamp series Industry and Technology of the German Federal Post (12 June 1979)

A wheel lo ader (in Swiss German: Trax) is a construction machine for loading and transporting goods over short distances. Equipped with a bucket, a wheel loader is suitable for earthmoving work or other loose materials such as gravel. There are wheel loaders with a total weight[1] of less than 2 t and more than 200 t.

Front loaders are closely related to wheel loaders. The basic machines here are usually tractors or Unimogs, which are equipped with a swing arm. These machines are also called front loader tractors. If the swing arm is mounted on a tracked undercarriage, it is referred to as a crawler loader; this vehicle is also called a tracked loader or tracked loader to distinguish it from wheel loaders.

A smaller type of wheel loader is the skid steer loader. It is characterized by smaller dimensions and high maneuverability.

A special type of wheel loader are those used in underground mining, which are characterised by their low overall height.

Wheel loaders can be equipped with a scale to determine the mass of the load almost exactly during loading.

History

The first wheel loaders were developed in the 1920s and 1930s from agricultural tractors, which were fitted with cable-operated loading buckets. From this, independent construction machines developed in the 1940s and 1950s, which were soon produced in series by many domestic and foreign manufacturers.

After rear-wheel and all-wheel steering, articulated steering became established in the 1960s and 1970s: Here, the frame is split in two about halfway along its length, and the front and rear carriages are connected by an articulated joint with a vertical axle. In 1994, the manufacturer Liebherr introduced stereo load ers (brand) for rather smaller weights, which achieve special manoeuvrability through articulated steering and at the same time rear-wheel steering. Articulated steering achieves that the bucket with the front carriage can be “shifted” sideways a little bit when standing, furthermore the lifting mechanism does not need to leave any space for steering movement of the front wheels. Usually, the driver sits approximately above the articulated joint, and the cabin can be connected to the front or rear carriage.

In 1954, the first Liebherr Elefant Type 90 wheel loader prototype with 90 hp and 12 t total mass used skid-steer(ing) with a very short wheelbase. Steering is done by braking the wheels on one side only or even driving them in the opposite direction. This principle of skid-steering is used on all tracked vehicles, on skid-steer loaders on 4 to 6 wheels and on ARGO amphibious off-road vehicles (from 1969 or 1971) with 6 or 8 wheels.[2] This also makes it possible to turn while stationary.[3]

Components

A wheel loader usually consists of the components:

  1. Front and rear carriage, connected by articulated joint (articulated steering)
  2. Lifting frame
  3. Attachment (e.g. loading bucket, loading fork)
  4. Motor
  5. Driver’s cab

The lifting frame is usually designed in Z-kinematics or parallel kinematics (P-kinematics), whereby kinematics refers to the movement geometry. Some manufacturers also offer combination solutions (e.g. Volvo TP kinematics). With Z-kinematics, the extendingcylinder causes the attachment to tilt/fold in. This allows higher forces to be applied to the tipping movement than with parallel kinematics, where the retractingcylinder causes the attachment to tilt in. In most cases, a more precise parallel guidance of the implement is possible.

Key figures

The range of parameters for wheel loaders is very wide, as there are many different sizes. Small loaders, for example, achieve an engine output of between 20 and 60 kW and large loaders an output of between 70 and 590 kW. The operating weight can be up to 7.5 t for the small machines and up to 90 t for the larger machines. The loading bucket holds between 0.35[4] and 10.5 m³. In loading mode, the maximum speed is 15 km/h, depending on the model; when empty, the wheel loader reaches up to 40 km/h.

Attachments

  • Standard shovel for bulk materials, such as gravel or topsoil
  • Light goods bucket with larger volume for light goods such as grain
  • Combi/folding bucket with hydraulic front flap for easier pick-up of goods
  • Pallet/loading fork for palletised goods
  • Roadsweeper
  • Mixingbucket for mixing concrete
  • Stone fork
  • Snow blade (hydraulic) for clearing heavily snow-covered roads and paths
  • Snow blower
  • Bale pricker for pricking out larger plants

Records

LeTourneau L-1850 wheel loader passes a Caterpillar Cat-793C dump truck at KCGM Superpit, Kalgoorlie

The largest wheel loader in the world is the LeTourneau L-2350 with an operating weight of 262 t and a payload of 72.6 t, an engine output of 2300 hp and a standard bucket capacity of 40.5 m³.[5]

It is used worldwide to load overburden or conveyed material in large opencast mines. Often these machines are used when the primary mining equipment (cable excavator, hydraulic excavator) is not available due to technical problems. The LeTourneau machines are diesel-electrically driven, which is a special feature for wheel loaders.

Steering

An articulated wheel loader loads pallets

Steering on wheel loaders is usually by articulated steering. The joint is located approximately in the middle of the machine and is hydraulically driven. The driver usually sits on the rear carriage, more rarely on the front carriage. The driving experience is completely different in each case.

Some wheel loaders from e.g. Kramer do not have articulated steering, but the steering is carried out via all-wheel Ackermann steering. This principle is characterised by a higher stability in the steered state, but has the disadvantage that the steering movement only has an effect while driving. With articulated steering, the bucket can also be aligned laterally when stationary. Another disadvantage of all-wheel steering is that the wheel loader swing arm swings out of the turning circle at the front when cornering, whereas a wheel loader with articulated steering “bends around the curve”, so to speak, which makes work enormously easier, especially in confined conditions, whereby all-wheel steered wheel loaders have a smaller turning circle.

Liebherr’s stereo steering combines both principles.

The tank steering of skid steer loaders has the disadvantage that the equipment churns up the ground when changing direction. Their use should therefore be limited to paved areas where they do not cause damage and can turn more easily. However, a relatively high level of tyre wear must then be expected.

Security

  • In Germany, wheel loaders are required to undergo an annual U-VV inspection in accordance with the guidelines of the employers’ liability insurance associations.
  • A certificate of competence (driving licence) for driving construction machinery wheel loaders is a prerequisite in Germany for the proper use of all power-driven construction machinery in accordance with the guidelines of the employers’ liability insurance associations.

Manufacturer

HEPCO HWL110-2

Wheel loaders are manufactured by a variety of companies around the world. Among them are manufacturers that specialize in the construction and development of special wheel loader designs. Companies that manufacture wheel loaders include JCB, Caterpillar, Paus, Liebherr, Volvo CE, Atlas Weycor, Terex, Komatsu, Hitachi, Wacker Neuson with Weidemann & Kramer, Case CE, BelAZ and Mecalac.

See also

  • Salvage clearing equipment
  • Crawler Loader
  • List of construction machinery
  • List of construction machinery manufacturers
  • Swing loader
  • Telescopic handler

Individual references

  1. Note actually: Mass
  2. ARGO amphibious vehicle 6×6 and 8×8 atv-quad.org, retrieved 6 December 2017.
  3. Milestone 10 liebherr.com, retrieved 6 December 2017.
  4. Kramer:Product.Retrieved August 8, 2018.
  5. Data sheet(Memento of Originals june 11, 2014 on the Internet Archive) Info:The archive linkwas automatically inserted and not yet checked. Please check original and archive link according to instructions and then remove this note.@1@2Template:Webachiv/IABot/www.letourneautechnologies.com (PDF; 615 kB)

Web links

Commons: Wheel loader– Image collection

Wiktionary: wheel loader– Explanation of meaning, word origin, synonyms, translations