In recent years in the world there has been a steady transition from the use of mining equipment for rope excavators of traditional design to hydraulic excavators. Until recently, hydraulic machines completely replaced cable cars only in the class of light construction excavators, and today there is a planned replacement in the class of powerful quarry. Complexes are being implemented with the use of super-powerful hydraulic excavators with a bucket capacity of up to 40 m3, coupled with heavy dump trucks with carrying capacity up to 380 tons, and this process is quite natural.
The design of the modern mechanical shovel is not fundamentally different from the design of the first excavators of the 1830s (the first mention of such digging technique dates back to 1420!). For a century and a half the drive evolved from steam to electric (or diesel), a crawler (or stepping) course was introduced, the excavators became full-turning. Over the years, the capacity of the machines has grown, overburden vaults of the EVG-35.65 type have been created, but the basic scheme of the working equipment has not changed — single-beam or double-beam handle, support unit on the boom of the corresponding structure, pressure mechanism, hoisting winches. The circuit is reliable in operation and unpretentious in maintenance, metal consumption, does not require special accuracy in manufacturing and installation in comparison with the hydraulic drive.
The appearance of a three-dimensional hydraulic drive made it possible to create new schemes for the working equipment of the excavating machine, which reminded now of a mechanical arm rather than a mechanical shovel. Features of the excavator have expanded to a large extent: selective excavation, front stripping, better conditions for loading the rock into transport, shorter work cycles, etc. In fact, this is a new type of equipment, the application of which increases the intensity and quality of mining.
The increase in the level of reliability of hydraulics for some time has made it possible to successfully compete with hydraulic excavators with ultra-reliable and non-destructible mechanical shovels. It is already possible to compare the resource of both types of machines. The use of electronic systems for monitoring the operating parameters of the hydraulic drive, especially the monitoring of the working fluid, helps to ensure trouble-free operation, reduce wear of hydraulic units.
Hydraulic drive has a significant margin of opportunity to improve it as such. The use of a hydraulic drive makes possible different variants of the layout of the machine, especially the working equipment. The classic design and layout of the rope excavator of the ECG type has already exhausted itself, further improvement is possible only with reference to the power drive of the main mechanisms — the course, the turn, the winch. This can improve individual performance, but overall the machine remains at the level of a traditional mechanical shovel.
Production of heavy quarry excavation
equipment has always been the lot of specialized powerful enterprises. Firms — manufacturers of quarry excavators are few, you can count on your fingers. The very possibility of producing such a technique already brings the manufacturer to the elite of the machine-building industry, but there are also leaders in this elite group.
The deciding voice when choosing a leader is the buyer. Technology can be as pleasing as it is complex and high-tech, but it is by sales volume that it is possible to give the most objective assessment of the company’s activities all the way from concept development to machine implementation in metal and marketing work.
For a long time, many users of quarry equipment around the world prefer the excavation technology of Hitachi Construction Machinery Co., Ltd. (HCM). The company was founded in 1970 as a result of the division of functions of Hitachi Ltd. In 1979, a career excavator UH801 was commissioned, which became the first in the class of heavy quarry, and since then more than 400 units have been manufactured. heavy excavators (weighing more than 150 tons). Every year the company around the world closes from 30 to 50% (depending on the country) of the market of excavating equipment — light, medium and heavy. Today Hitachi is the undisputed leader among the strongest competitors, a well-known brand.
What caused this success? Naturally, this is the result of fruitful and thoughtful work of the company for decades.
In such industries, there are no casual victories. When asked why the consumer chooses their products, HCM responds as follows:
- high availability of equipment during operation;
- low operating costs;
- Better fuel economy;
- technological flexibility;
- Lower maintenance requirements.
These are not advertising slogans. In the mining operations of PT Kaltim Prima Coal (East Kalimantan, Indonesia), the first EX3500 delivered there between December 1990 and December 2003 was more than 88,000 mph. In total, according to the results of work 12 units. EX3500 for the entire period of operation at this enterprise, the availability of equipment on average was about 92%! The facts speak for themselves. Such indicators became possible due to the correct policy of HCM and the company’s dealers in the field of after-sales service. It is the high-quality supply and attraction of qualified service specialists that gives such excellent results. The consumer’s lot is only the extraction of raw materials without distraction of attention to maintaining the machine’s efficiency.
Hitachi Construction Machinery is an engineering company. The company’s specialists have chosen their own way of creating high-tech equipment. In each branch of machine building there are recognized firms whose products are time-tested and are of the best quality. This product (hydraulic components, diesel engines) is used to complete the finished Hitachi excavators. Assembly of the quarry machines themselves is carried out in the assembly shops of HCM in Japan, in the same place they make all metal structures using modern welding technologies.
One of the suppliers of hydraulic equipment for HCM excavators is Kawasaki, well-known for its products, among other things, in the field of hydraulics and related systems. The company produced its first products back in 1916, and today has accumulated a wealth of experience in the production of such equipment. Kawasaki Precision Machinery Group (KPM) is part of Kawasaki. Under the KPM brand, high-quality hydraulic components are produced for mobile road construction equipment (hydraulics of excavators, hoisting-and-transport machines, loaders, etc.), hydraulic components of ship equipment and much more. All Kawasaki products undergo strict quality control and have corresponding international certificates of conformity.
On machines with a working mass of less than 80 tons, Isuzu diesels are traditionally put, which have proved themselves well in operation. For heavier excavators, Hitachi diesels are installed (models EX8000, EX3600, EX1900). In addition, the supplier of diesel engines for heavy excavators (EX5500, EX2500, EX1200) is Cummins. Cummins was founded in the USA in 1919. The powerful Cummins diesel engines have always been distinguished by high quality, good performance, reliability and durability. The engines comply with all world standards, which guarantees their reliability and durability, even in particularly difficult operating conditions — in mining operations. Cummins does not need recommendations and is familiar to consumers around the world, including in Russia. At the request of the customer, an electric motor of Hitachi production of appropriate design and power for 6 … 10 kV may be installed as the primary engine.
From the assembly shop comes a high-tech machine, adapted to work in the most severe conditions of quarries. The updated line of heavy duty excavators Hitachi weighing 180 tons includes six models (starting with EX1200-5D). All models (except EX8000) can be produced in a version with a backhoe bucket («Backhoe Bucket») or «Shovel Bucket».
The hydraulic system includes Hitachi’s ETS (Electronic Total control System), which is designed to optimize the operation of all hydraulic equipment, starting from the main pumps and ending with all the executive units (power cylinders, hydraulic motors). ETS automatically makes adjustments to the operation of hydraulic systems, providing control and access to the most efficient mode of operation of the equipment, and performs self-diagnostics. In order to optimize the operating parameters, the direct development of heavy faces for excavators establishes an additional balancing hydraulic cylinder that is hydraulically connected to the main power circuit, thus shortening the working cycle and protecting the main hydraulic cylinder of the handle. Used the system of automatic equalization of the bucket angle during digging.
The main elements of the working equipment are a hilt and boom of an all-welded box-section design made from high-alloy steel with a high tensile strength, and also a welded ladle, the elements of which are made of wear-resistant high-alloy steel.
On the turntable, the arrangement of all mechanisms is performed with the condition of ensuring free and safe access of maintenance personnel to the main units and units. The support ring is assembled from molded elements with smoothed outline contours welded to the lower support frame and is capable of withstanding particularly high loads.
The running gear is caterpillar type. The supporting frame is assembled in the form of welded construction of alloy steel with the expectation of carrying out particularly heavy work. The side caterpillar frames are welded to the supporting frame. Supporting and supporting rollers, tension wheels and drive sprockets are filled with lubricant and protected by floating seals. Thermally treated fingers of caterpillar links are made with dirt-tight seals. The mechanism of the tension of the caterpillars is hydraulic. The caterpillar shoes are made of a special rolling alloy with induction hardening, which ensures their high wear resistance.
HCM has long ceased to be just a supplier of certain types of equipment. Today the company offers a complete solution for specific customer requirements, including the use of hydraulic excavators with heavy-duty dump trucks Hitachi. Qualitative, taking into account the specifics of the application, the selection of equipment with the best combination of linear parameters of machines produced at HCM enterprises will allow to achieve the best results in work.