The history of roadheaders

English Channel Machine. The drawing comes from the book ‘Urabianie złóż. Część 3. Urabianie kombajnami. Górnictwo – tom 4.’, Wacław Lisiecki, Prof. BEng, MSc; Wacław Regulski, Associate Professor, BEng, MSc; 'Śląsk' Publishing House, Katowice, Poland, 1957.

A cutting machine (a roadheader or a shearer loader) means – not only in the context of mining – a machine composed of multiple units and capable of performing several different functions simultaneously. A roadheader is a machine intended for the excavation of underground headings, i.e. a machine which performs several functions within that process. A heading is an excavation characterised by considerable length in relation to its cross-section. These include  various roadways, adits, crosscuts, drifts, inclines (sometimes shafts and staple pits are also included in this category). It is worth noting that, originally, the headings were simultaneously the working faces. 

The first known roadheader was built in 1876 and was designed for simultaneous performance of three operations: extraction, loading of the excavated material and haulage (transport) of that material behind the face. The machine, powered by compressed air, was called the English Channel Machine and was designed to drill a pilot tunnel beneath the English Channel (hence the name).

The task of the first roadheader was to drill a tunnel with a diameter of 2.1 m, which was to be later increased to a size that could accommodate a train. Even then, it was planned to connect Great Britain and France by a railway tunnel. The roadheader extracted the limestone face by drilling, loading the excavated material, transporting the material to its back and discharging it into mining tubs. The machine had no undercarriage and moved on skids. Results were encouraging – approx 2,400 metres were efficiently drilled. However, the fear that the French army could attack the British Isles by land caused the work to be stopped. New tunnels were built over 100 years later. The heading machine was also forgotten for a long time.

In 1918, the Mc Kinley Entry Driver – a narrow face coal mining machine designed to work in room and roadway systems – was introduced in the USA. However, it failed to attract much attention. Nevertheless, the concept of this particular mining machine returned in the form of Borer Miner produced by Marietta, used in the USA, and beyond, to extract potassium salts in a room and pillar system. These types of mining machines, which extract the entire cross-section of a heading face, produced by various manufacturers, are widely used in the potassium salt mining industry. Nevertheless, the development of  heading machines was abandoned for a long time.

Across the Atlantic, machines for loading the excavated material in the form of stripper-loaders, as well as cutters for making cuts which accelerated the performance of blasting works in narrow faces of the room and pillar system were also built. Other machines for  full cross-section cutting, loading the excavated material and transporting also appeared in the USA, however these machines did not become the solutions for the future of the coal mining industry. This can be attributed to the fact that coal seams  are characterized by varied thickness and can occasionally be undulating; however there was a need for machines capable of addressing such changes. An additional problem was the rapid wear of the cutting heads, or rather the cutting picks of the mining machines of that time. This meant that advances in material engineering were necessary. The models developed  in the USA were still not heading machines, but rather machines for mechanised extraction of coal in a room and pillar system. It should be noted that the longwall system appeared there only by  the end of the 1960s. 

European experiments

In Europe, where the longwall system became widespread much earlier than in the USA, the demand for high performance roadheaders appeared shortly after World War II. In the former USSR, after a period of experimentation with drilling machines, the first advanced roadheader solutions were created, i.e. self-propelled mining machines for cutting loading and transporting  the excavated coal beyond the face area were developed. One such example was the PK-2 roadheader, which was basically a cutter assembly and conveyor belt built into the machine; however, it failed to meet the expectations. Successful experiments related to such roadheaders, used in the Polish coal mining industry also include the PK-3 (KPU-4) and PK-4.

FR 250D Roadheader

These machines were equipped with an axial head which extracted the face spotwise. Loading of the excavated material and its transport to the back of the machine were performed by a single-chain scraper conveyor with a side chain. The machine moved on a tracked chassis. Many technical solutions used in those roadheaders have set the standards for such machines for many years – Dosco Mk-2A roadheaders, the production of which ended by the 1990s, are still in use today. For decades, the axial cutter has been the hallmark of Soviet, and later Russian, roadheaders, but also of their British licensed clones. Over the years of development of Soviet roadheaders, the most important changes have been made to the system of loading the excavated material and transporting it behind the face. A simple conveyor and stripper-loader appeared, which were introduced as a stand-alone machine by Joy even before the war. In essence, the newer roadheaders were a stripper-loader fitted with a boom with an axial cutter. Such cutter solution made it possible to create roadways with a cross-section of almost any shape, and thus also to use yielding arch supports, which are nowadays dominant in the Polish coal mining industry. Many such machines (PK-7, PK-9R, 4PP-2) worked in Polish coal mines even until the 1990s and enjoyed a good reputation. 

Evolution of roadheader designs

However, the Soviet roadheaders also had their drawbacks and limitations. For this reason, during the period of intensive development of the Polish coal mining industry in the 1970s, it was decided to purchase a license for the AM-50 roadheader, manufactured by the Austrian company Voest Alpine, and starting of its in Poland. This relatively light roadheader (less than 25 tons) was nevertheless much heavier and stronger than its Soviet predecessors and allowed extraction of a larger section of the face from a single position. A transverse cutter with two hemispherical heads slightly increased the efficiency of coal extraction, while the ability to extract a face with a cross-section of nearly any shape was retained. However, the design of the AM-50 roadheader, which in a significantly improved version is still produced at FAMUR SA (Remag), was not entirely developed in Austria. It stems from the Hungarian F-6 roadheader, which, in turn, was based on the F-2 and F-4 roadheaders, serially produced for the mines of the Hungarian Tatabanya coalfield as early as the beginning of the 1950s.

One might ask why Polish engineers did not design their own roadheader at the time. The answer is fairly simple: there was a top-down division of labour within the Council for Mutual Economic Assistance. For a long time, we did not produce roadheaders, but we did and continue to produce quality longwall shearers, which have become our, Polish, specialty within that very division. Nevertheless, attempts were made in Poland to build heavier roadheaders for rocks harder than coal. The fruit of these works was the K-160 roadheader, whose tests were ultimately unsuccessful. KOMAG also developed the KCX-250 heavy duty roadheader, which, although was built, introduced to the market at a bad time – the beginnings of the Polish economic transformation of the 1990s and denationalization of mines meant that no-one was willing to take the risk of its implementation. In the last decade of the 20th century, various domestic producers also made attempts to develop new roadheaders, but without much success. Production of KTW series roadheaders was launched on a small scale this century. 

However, the production of AM-50 was initially undertaken by Konstal in Chorzów in the 1970s, followed by serial production at Zamet Tarnowskie Góry, where these machines were produced on a small scale until the 1990s. However, since the early 1980s, the main producer has been Remag – previously one of the many coal industry repair plants, now a part of the FAMUR Group. Development works were also undertaken in order to better adapt the roadheader to customer requirements; these included increased extraction height, increased scope of permissible longitudinal inclination, replaced electrical equipment and widened tracks. The R-120, R-130 and R-150 roadheaders were developed to tackle the challenge of increasing the power of the cutter head  to expand the capacity to mine rocks harder than coal. Finally, noticing the development limitations of the base model, i.e. the AM-50, the KR-150 medium-weight roadheader was designed. It was followed by an even heavier roadheader, now known as the R-2000. Of course, all roadheaders were used to drive roadways with chock support.

Much has changed since the beginning of production of roadheaders in our country and nowadays these machines are equipped with working platforms and hydraulic manipulators which facilitate installation of steel support. Remag later became a part of FAMUR SA and new activities related to expansion of the roadheader offer were undertaken. A license was purchased for the Dosco LH-1400 roadheader, which, after many years, was once more, like the old Soviet machines, equipped with a longitudinal cutter and had a loader conveyor with a moving end, which allowed discharging the excavated material onto a conveyor fitted next to the roadheader or onto a shuttle car. Finally, the roadheader was factory equipped with two bolters. However, the roadheader offered in such a configuration as the FR-250 did not attract interest from the Polish mining industry. This may seem a bit surprising, as the labour-intensity and cost of construction of steel support would indicate that roof bolting is advisable wherever possible. Only the version of the FR-250 without bolters, with a transverse cutter and a fixed loader found use in one of the Polish mines. This is all the more surprising when one considers that Polish companies talk about using bolter-miner type heading machines, which are also equipped with bolters. However, it should be noted that these very large and heavy machines can only drive roadways with a rectangular cross-section, are capable of mining almost exclusively coal and are very sensitive to longitudinal and transverse inclinations. They are also not particularly suitable for work in conditions of high methane hazards. 

FR 160 during testing in FAMUR Remag Roadhading System Division in Katowice.

For several years now, FAMUR SA has also been offering the medium-weight FR-160 roadheaders, which are in use in several Polish mines. Despite the fact that, for various reasons, the cross-sections of roadways, including main gates, are increasingly becoming larger, Polish customers are very fond of the AM-50Z and ZW, with over 100 machines of this family are in  use in Polish mines and over 2700 in total built in Polish factories.

The relatively large roadheader market in Poland and its specific requirements, which differ from those of other customers, mean that FAMUR wishes to primarily fulfil domestic needs. That said, in recent years, our roadheaders have also found their way to Turkey, Bosnia and Russia.