Mining is one of the most demanding professions in the world. It constantly involves confined underground workings, dust, noise, and hard rock that must be excavated metre by metre. It is no surprise, then, that mining engineers have spent many years looking for ways to make miners’ work easier and safer. One of the results of these efforts is the roadheader – a machine that takes over the heaviest part of the miner’s work and allows people to focus on what no equipment can replace.
If you want to understand why roadheaders are so highly valued in mining, read our article and take a closer look at them from the ground up. Enjoy the read!
Roadheader – what exactly is it?
A roadheader is a self-propelled mining machine designed for the mechanical excavation of underground roadway-type workings – roadways, tunnels, and cross-cuts in rocks of varying hardness. It is used wherever underground infrastructure needs to be developed: in hard coal and lignite mines, metal ore mines, salt mining operations, as well as in the construction of road and railway tunnels.
MR-340X roadheader after professional overhaul – own project
In simple terms, a roadheader is a machine that supports miners in the extraction and cutting of minerals – coal, gypsum, potash, and many other rock materials found in mines. Where miners once had to laboriously break material away with picks, today a roadheader enters the face and performs the task faster and more safely.
Before we explain how the actual cutting process takes place, it is worth taking a closer look at the construction of this machine.
How is a roadheader built? Key components of the machine
At first glance, it can be difficult to identify the individual elements in the structure of a roadheader. In reality, however, the machine consists of several main assemblies, each responsible for a different stage of operation.
Structure of a typical roadheader – own work
Looking at a typical roadheader from the front, we can identify the following elements:
- Cutting head – the working head fitted with tangential picks, also known as cutting picks. It is mounted at the end of a movable boom. These picks come into direct contact with the rock and break it away during cutting. The cutting head is the heart of the entire machine.
- Operator’s cab – the control station from which the roadheader operator controls the machine and all its systems.
- Cutting head boom – a movable boom that allows the cutting head to move vertically and horizontally, which enables the roadheader to cut the entire face.
- Gathering arms – two cross-shaped elements with curved arms that collect the cut material from the loading table and direct it onto the chain conveyor.
- Travel system – the complete drive and mobility module, most often crawler-mounted, which allows the roadheader to move along the floor of the working.
- Loading table – a steel ramp or apron where the cut material, such as hard coal, is collected.
- Chain conveyor – a material conveyor running along the full length of the roadheader, carrying the excavated material away from the machine.
How does a roadheader drive a roadway?
When the roadheader is positioned in front of the face, a precisely synchronised operating cycle begins. From the operator’s cab (2), the operator positions the boom and starts the cutting head (1). The head begins to rotate, while the tangential picks cut into the rock, breaking off successive portions of excavated material. The cutting head boom (2) moves slowly vertically and horizontally, allowing the head to progressively cut the rock across the entire face of the excavation.
The detached material falls onto the floor, where it is immediately taken over by the loading table (6) and gathered by the gathering arms (4). From the loading table, the material is transferred onto the chain conveyor (7), which runs along the full length of the roadheader. In this way, the excavated material is carried away from the machine, where it is then taken over by the haulage system.
During operation, the travel unit (5) gradually moves the roadheader forward as required. The operator continuously monitors the advance rate, boom position and operating parameters of the individual systems.
The heart of the roadheader – the cutting head
The cutting head is the component that performs the hardest work in a roadheader. It is the only element that comes into direct contact with the rock being cut, which means it must withstand continuous impact, friction, and enormous cutting forces. To better understand how the cutting head works, it is worth looking at it more closely:
Cutting head structure in a roadheader – own work
The most important role in the cutting head assembly is played by tangential picks (3), also commonly referred to as cutting picks. The picks are usually set at an attack angle of 45–55° relative to the rock surface. They do not strike the rock perpendicularly, but cut into it at an angle, which significantly reduces cutting resistance and limits wear on the pick itself.
Unused cutting picks mounted in the holders of the cutting head – own project
The effect is similar to what happens when slicing bread: a knife guided at an angle passes through the crust much more easily than when it is pressed straight down into the loaf. As the head rotates, each cutting pick generates a cutting force of around 5–20 kN. Since several dozen picks may work on the head at the same time, the total load acting on the cutting head can exceed 200–400 kN.
For comparison, a high-quality cordless screwdriver can reach a torque of around 100 Nm, whereas the cutting head gearbox of a medium-sized roadheader operates at 20,000–50,000 Nm. In other words, the forces acting on it may be several hundred times greater.
The picks are seated in tool holders (1), which secure them to the body of the cutting head while allowing quick replacement. This is essential because cutting picks wear relatively quickly, and their regular inspection is a basic requirement for the reliable operation of any roadheader.
Brand-new Minostar pick holders
The required force and rotation are supplied by the cutting head gearbox (2) – a mechanical transmission system that transfers power from the roadheader’s electric motor directly to the cutting head.
The cutting head gearbox usually operates at a rotational speed of 30–60 rpm. As you can see, the rotational speed is relatively low. What matters here is not speed, but high torque and precise cutting.
Most common types of cutting heads
One of the key features that distinguishes different roadheaders is the type of cutting head – more specifically, how the head is oriented in relation to the axis of the machine:
Roadheader with a transverse cutting head – illustrative graphic
Transverse cutting heads have the head positioned perpendicular to the axis of the roadheader. This is the dominant solution in coal mining, valued for its high cutting performance and relatively simple design. It performs well in soft and medium-hard rock formations.
Roadheader with a longitudinal cutting head – illustrative graphic
Longitudinal cutting heads, also known as milling-type cutting heads, have the head mounted parallel to the axis of the boom. Their shape is more similar to an elongated cutter or cone. This configuration allows for a much more accurate excavation profile and performs better in harder rock formations.
Longitudinal cutting heads are commonly used in tunnelling roadheaders and wherever precise control of the roadway cross-section is important.
Minostar – professional support at every stage of a roadheader’s service life
A roadheader is an investment worth millions and, like any machine operating in extreme conditions, it will sooner or later require service intervention. Whether downtime in a mine lasts a few hours or several days largely depends on whether the operation is backed by an experienced and well-equipped technical partner – such as Minostar.
At Minostar, we specialize in comprehensive roadheader support. We provide assistance at every stage of machine operation – from ongoing repairs, through overhauls and modernization, to the supply of high-grade spare parts for the most common roadheader types, in particular: AM-50, AM-75, AM-105, MR-340, MT-620, and MR-520.
See how the Minostar RESTART program works!
What do we offer?
1. Roadheader repairs
Fast diagnostics and efficient fault removal to restore machine availability as quickly as possible. In this area, what matters is not only our technical expertise, but also access to the right spare parts. We keep most of the essential roadheader components in stock, so there is no need to wait for weeks for delivery from a distant warehouse.
2. Major overhauls, restoration overhauls, and modernization
A major overhaul is often the most cost-effective alternative to purchasing a new roadheader, especially when the machine has already been adapted to the needs of your operation, but years of intensive use have taken their toll.
Our offer also includes adapting roadheaders to new operating conditions, current safety requirements, the specific demands of a given deposit, and many other needs.
3. Spare parts for roadheaders
High-grade, proprietary spare parts for a wide range of roadheaders. Our spare parts are not only excellent replacements for original components, but often include additional improvements that are difficult to find in standard factory parts. Minostar roadheader spare parts are based on more than 12 years of industry experience and are designed by practitioners who understand the realities of underground operation.
4. Minostar RESTART program – a new life for your roadheader
One of the key strengths of Minostar’s offer is the proprietary RESTART Program – a comprehensive pathway for extending the service life of mining machinery, developed in line with the principles of the circular economy.
As part of the RESTART program, we have developed three pathways for the repair, modernization, or restoration overhaul of roadheaders. Each of them responds to the growing challenges faced by the mining industry: the need to optimize operating costs, extend the service life of specialized machinery, and reduce environmental impact.
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How does a roadheader excavate a working?
Regardless of the cutting head design, once the roadheader is positioned in front of the face, a precisely synchronized working cycle begins. The operator sets the boom from the cab and starts the cutting head. The head begins to rotate, while the tangential picks cut into the rock or coal seam, breaking away successive portions of material.
The cutting head boom moves slowly in both vertical and horizontal directions, so that the head covers the entire face of the working – from bottom to top and from side to side.
The cut material falls onto the floor, where it is immediately taken over by the loading table and gathering arms. The gathering arms work rhythmically – collecting material from the loading table and directing it onto the chain conveyor, which runs along the entire length of the roadheader. In this way, the material is carried away from the machine and transferred to the downstream haulage system.
Chain conveyor in an MR-340X roadheader – own photograph
Throughout this process, the travel system gradually advances the roadheader, while the operator continuously monitors the feed rate, boom position, and operating parameters of individual systems.
This synchronization – simultaneous cutting, gathering, and conveying of material – is what makes the roadheader so efficient compared with traditional excavation methods.
What happens to the cut material? A few words about haulage systems
A roadheader completes its part of the process when the cut material leaves its built-in chain conveyor. From that point, the material is handled by downstream haulage equipment, and the efficiency of this system determines whether the working can be advanced without unnecessary stoppages.
Directly behind the roadheader, the material is usually transferred onto a discharge chain conveyor – a longer counterpart of the conveyor built into the machine, which moves the material along the working and deeper into the mine transport system.
From there, the material is transferred to belt conveyors, which can transport it over long distances, often extending for several kilometres. The material is carried all the way to a loading station or shaft.
In mines where the layout of workings does not allow for a continuous conveyor system, shuttle cars and mine locomotives are used to transport the material in mine cars. At the surface, the material – such as hard coal, potash, or gypsum – is sent to a sorting plant or processing facility, where it is cleaned, classified, and prepared for further use.
It is worth noting that, in addition to comprehensive support for roadheaders, our company can also assist in maintaining the operation of haulage equipment – both through spare parts supply and service work.
Summary
The roadheader is one of the most important machines in the production chain of almost every underground mine. The condition of its components therefore has a direct impact on whether the mine continues to generate profit or whether downtime leads to serious losses. Understanding how a roadheader works and what components it consists of is the first step toward proper maintenance and fast response whenever something starts to deviate from normal operating parameters.
If you are looking for technical support for roadheaders, we invite you to contact the Minostar team.
We will be happy to advise you and select a solution tailored to the specific requirements and working conditions of your machine.
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