Wheel loader
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A wheel loader (in Swiss German : Trax ) is a construction machine for loading and transporting goods over short distances. Equipped with a shovel, a wheel loader is suitable for earthmoving work. There are wheel loaders with a total weight of less than 2 t and more than 200 t.
Front loaders are closely related to wheel loaders . The basic devices here are mostly tractors or Unimogs that are equipped with a swing arm. These machines are also called front loader tractors. If the rocker is mounted on a crawler chassis, one speaks of a crawler loader , this vehicle is also called a crawler loader or chain loader to distinguish it from wheel loaders.
The compact loader is a smaller type of wheel loader . It is characterized by smaller dimensions and high maneuverability.
A special design of the loaders are in underground mining used LHD , which are distinguished by their low height.
Wheel loaders to a scale equipped to be to determine the mass of the cargo loading.
history
The first wheel loaders emerged in the 1920s and 1930s from agricultural tractors that were fitted with rope-operated loading shovels. From this, independent construction machines developed in the 1940s and 1950s, which were soon being mass-produced by many domestic and foreign manufacturers.
After rear-wheel and all-wheel steering, articulated steering prevailed in the 1960s and 1970s : the frame is divided into two parts about half the length, the front and rear of the vehicle are connected by an articulated joint with a vertical axis. In 1994, the manufacturer Liebherr introduced stereo loaders (brand) for rather smaller weights, which achieve particular maneuverability through articulation and rear-wheel steering. Articulated steering means that the shovel with the front carriage can be "shifted" to the side a bit, and the lifting mechanism does not need to leave any space for the steering movement of the front wheels. The driver usually sits above the articulated joint, and the cab can be connected to the front or rear of the vehicle.
In 1954, the first wheel loader prototype from Liebherr Elefant Type 90 with 90 hp and a total mass of 12 t was skid steer (ing) with a very short wheelbase. You steer by braking the wheels on one side only or even driving them in the opposite direction. This armored steering principle is used in all crawler tracks, compact loaders on 4 to 6 wheels and the amphibious off-road vehicle types from ARGO (from 1969 and 1971) with 6 or 8 wheels. This also enables turning while standing.
Components
A wheel loader usually consists of the following components:
- Front and rear end, connected by an articulated joint ( articulated steering )
- Lifting frame
- Attachment (e.g. loading shovel, loading fork)
- engine
- Driver's cab
The lifting frame is mostly designed in Z-kinematics or in parallel kinematics (P-kinematics), whereby the kinematics means the movement geometry. Some manufacturers also offer combination solutions (e.g. Volvo TP kinematics). In the Z-kinematics of the leads from moving cylinder to tilt back / folding in of the attachment. This means that higher forces can be applied to the tilting movement than with parallel kinematics , in which the one moving cylinder causes the attachment to tilt in. A more precise parallel guidance of the attachment is usually possible.
Wheel loader (schematic)
Example for parallel kinematics
Example for Z-kinematics
Parameters
The range of parameters for wheel loaders is very extensive, as there are many different sizes. Small loaders achieve an engine output between 20 and 60 kW and large loaders an output between 70 and 590 kW. The operating weight of the small machines can be up to 7.5 t, and the larger machines up to 90 t. The loading shovel holds between 0.35 and 10.5 m³. In loading mode, the maximum speed is 15 km / h, depending on the model, while the wheel loader can reach up to 40 km / h when empty.
Attachments
- Standard bucket for bulk materials such as gravel or topsoil
- Light goods bucket with a larger volume for light goods such as grain
- Combination / folding shovel with hydraulic front flap for easier picking up of goods
- Pallet / loading fork for palletized goods
- Road sweeper for cleaning roads
- Mixing bucket for mixing concrete
- Stone fork for picking up stones
- Snow plow (hydraulic) for clearing roads and paths with heavy snow
- Snow blower
- Ball cutter for cutting out larger plants
Records
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.
It is used around the world to load overburden or conveyed goods in large open-cast mines . These machines are often used when the primary dismantling device (rope excavator, hydraulic excavator) is not available due to technical problems. The LeTourneau machines are diesel-electric , which is a special feature for wheel loaders.
steering
The steering on wheel loaders usually occurs by articulated steering. The joint is located approximately in the middle of the machine and is driven hydraulically. The driver usually sits on the rear of the car, less often on the front of the car. The driving experience is completely different.
Some wheel loaders from z. B. Kramer have no articulated steering, but the steering is via an all-wheel axle steering . This principle is characterized by a higher level of stability in the steered state, but has the disadvantage that the steering movement only has an effect while driving. With the articulated handlebar, the bucket can also be aligned to the side when standing. 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 much easier in confined spaces, with all-wheel-steered wheel loaders have a smaller turning circle.
The Liebherr stereo steering combines both principles.
The tank steering of the skid steer loader has the disadvantage that the devices stir up the ground when changing direction. Their use should therefore be limited to paved surfaces, where they do no damage and where they can turn more easily. However, relatively high tire wear can then be expected.
safety
- In Germany, an annual U-VV inspection is required for wheel loaders in accordance with the guidelines of the employers' liability insurance association.
- A certificate of competence (driving license) for driving construction machine wheel loaders is a prerequisite in Germany for the proper use of all power-operated construction machines in accordance with the guidelines of the employers' liability insurance association.
Manufacturer
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Wheel loaders are manufactured by a wide variety of companies around the world. These include manufacturers who specialize in the construction and development of special wheel loader designs. The companies that manufacture wheel loaders include Caterpillar , Paus , Liebherr , Volvo CE , Atlas Weycor , Terex , Komatsu , Hitachi , Wacker Neuson with Weidemann & Kramer , Case CE , BelAZ and Mecalac .
See also
- Rescue clearing device
- Crawler loader
- List of construction machinery
- List of construction machinery manufacturers
- Swing loader
- Telescopic handlers
Individual evidence
- ↑ Note actually: mass
- ↑ ARGO Amphibious Vehicle 6x6 and 8x8 atv-quad.org, accessed December 6, 2017.
- ↑ Milestone 10 liebherr.com, accessed December 6, 2017.
- ^ Kramer: Product. Retrieved August 8, 2018 .
- ↑ Data sheet ( Memento of the original from June 11, 2014 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 615 kB)
