Ewelina Ptak, KH-KIPPER, Poland, outlines the distinguishing features of a new mining body for tipper vehicles.
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"A tipping point for truck bodies"
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The growing cost of transport means that companies are creating new solutions to increase the load capacity of vehicles. The W1MV mining body, designed by KH-KIPPER, meets these new expectations. The lightweight tipper has a greater loading capacity than previous models of the mining body.
The one-way W1MV tipper is a vehicle designed for operating in mines in extremely difficult conditions. During high-fraction material transport, it is exposed to constant wear. The tippers are successfully used to transport loads from their place of extraction to their first destination, which, in most cases, is the crusher. As long as the terrain they traverse is sufficiently prepared, they make a suitable alternative to dump trucks.
The multi-functionality of the W1MV mining body used in truck chassis gives it a considerable advantage over traditional dump trucks: they can be used with a range of loads and a variety of destinations, such as mines or public roads. A further advantage of this kind of tipper is that it is multi-functional. They can be used for any kind of load, for example, coal, anthracite or metallic ore.
Design: the key to success
In mine construction, the floor is usually reinforced with longitudinal beams, cross beams or additional bendings. All of these elements aim to improve the stiffness of the construction of the floor. The distinguishing feature of the new WIMV mining body is the fact that there is no need to apply any reinforcements on the floor. The construction of the floor of the new body is made up of a HARDOX HB 450 high-resistantance steel plate with two bendings. In contrast to the previous model, where the floor that was made of three layers (steel and rubber), the new model is equipped with a floor that is made of only one layer of steel. Due to the removal of unnecessary elements, the construction has become more resilient and, thus, more durable and resistant to damage.
The plate of side walls is reinforced only with the upper profile, rear profile and front wall. The mechanical properties of HARDOX HB 450 steel, of which the side walls are made, ensure effective protection against damage.
Due to the fact that during the transportation of mining material, the body is exposed to difficult exploitation conditions, the main construction is made of resilient and high-resistance HARDOX HB 450 steel (floor 10 – 15 mm and side walls 6 – 10 mm), whereas the load-bearing constructions are made of durable STRENX 700 steel. The kinetic energy of the impact while loading rocks, even of considerable fraction, is successfully dispersed.
After a special preparation using Toolox steel, they can be even used to transport hot slag with the temperature of 500°C. Thanks to Toolox properties the tippers are resistant to high temperatures and wear.
Due to the half-octagonal construction of the body and sloped front wall, the unloaded material does not stick in the corners of the body. A raised rear part of the floor prevents the load from falling out while driving on an incline (particularly beneficial with fraction material). The rear SNEEP shovel allows for an easy unload without heaping the load on wheels. A big roof has been mounted in such a way in order to secure the upper profile of the front wall against falling elements during loading.
Main design features
- The removal of unnecessary elements of the construction improves the resilience of the body and prolongs its durability period.
- Reducing or eliminating damage to the construction caused by loading big rocks.
- Lowering the centre of gravity of the whole vehicle ensures greater stability during unloading of the material.
- Reducing the number of elements of the body and simplifying their shapes reduces the time of production and material demand.
- Lowering of the body’s own weight increases its load capacity. The driver can therefore transport more material in the same period of time.
- The costs connected with fuel consumption are due to a lower weight.
- Reducing repair costs due to a smaller number of spare parts.
Case study: Budpol
Limestome is commonly associated with school chalk or decorative face panels, which are easy to break, cut and work on. Unfortunately, this type of material can cause problems when it comes to transport. Devonian limestone has been used for over 12 million years. In Miedzianka near Kielce, the largest Nordkalk limestone mine and plant is located. The exploitation of the limestone deposit is performed by the Budpol company. Its 14 tippers constantly work in the Miedzianka mine.
Limestone is a raw material used in road construction, agriculture, the chemical industry and many other industries. Each of these sectors have different needs, thus the stone has to go through several crushing stages before different fractions are delivered to customers. The final stage is divided between rail and tipper transport, whereas the transport inside the mine is a task for special tippers on truck chassis or dump trucks. One might think that the latter has a considerable advantage over the first ones due to greater load capacity and volume. The reality, however, looks different.
Most limestone mines located near Kielce are situated on a very limited area set out by two old excavations and protected terrains. The technological routes as well as manoeuvring areas by the crushers are very narrow. The wheelbase of the chassis must be chosen by taking into consideration manoeuvrability. Dump trucks are not suitable for these kind of conditions, not even articulated ones. At the Miedzianka site, where Budpol operates, there are dump trucks but they are used only for transporting particular fractions between crushers and stockpiles. On the road between excavation and treatment plants, the only vehicles used are big-volume rear tippers on truck chassis. To begin with, the used dump trucks lost the ability to compete with them due to manoeuvrability. Other reasons included increased exploitation costs connected to higher fuel consumption and tyre costs, lower speed at a relatively long distance and also maladjustment to loading machines in the mine. In order to unload the aggregate, one should reverse to the unloading basket of the crusher but the space is very limited. Hence, the choice of a short classic mining tipper. It is also a matter of stability during unloading; a 6 m body is already a challenge. Budpol has gained such experience since 2004 by winning contracts as a subcontractor. Of course the most important goal is to cut the costs, which are very significant for the customer.
Big impacts during loading of large rocks have a considerable influence on chassis. The loading cycle is repeated 20 times per shift, 60 times per week; so choosing the right body for this task is one of the key issues for Budpol. The Miedzianka mine is a good testing area for tippers. Budpol and KH-KIPPER have cooperated for the last ten years, leading to dedicated solutions. The high-resistance of the body against aggressive aggregate is not everything: one has to take into consideration the proper axle load distribution and prevent the load against falling out of the body. Previously, typical mining tippers without the rear wall and with raised floor in the rear part have been used. This solution was not adequate because the trucks were loaded high above the upper profile of the body and the limestone kept falling out. The operators loaded the bodies closer to the front wall making the front axles overloaded and, as a consequence, the front suspension, tyres and steering system were damaged much faster. However, even in this case, a lot of load fell on the road. On limestone rocks with sharp edges, the tyres were worn out immediately.
KH-KIPPER has tried many innovative solutions and, although not all of them turned out to be successful, all of them looked promising as far as the weight was concerned. Only the latest W1MV mining body has provided the solution to all problems. The construction of the body involves high-quality steel, which is relatively easy to form and can be used in a design of the body. There are no typical outside reinforcements of the side walls; they were replaced with bendings of HARDOX 450 steel plates and upper profile reinforcements. The weight of the body was reduced and the construction itself became simpler, it has fewer elements, thus, the labour intensity was also reduced. The body is closed with a rear wall lifted by a chain mechanism. The simple solution allows the operator to load the body evenly in order to put more load on rear-driven axles. The cab is less exposed to falling load so the roof does not have to be so massive.
Budpol has actively participated in the production process, paying attention to details that are important for the exploitation realities that could have been overlooked by the constructors.
This article was first published in World Coal's May issue. To receive your free copy of the magazine, click here.
Read the article online at: https://www.worldcoal.com/special-reports/30062017/a-tipping-point-for-truck-bodies/