Minostar MR50 Roadheader

Operating capabilities of the MR50 roadheader

The Minostar MR50 is a roadheader designed for excavating small- and medium-sized underground workings. Depending on the selected specification, the machine provides a cutting cross-section ranging from 16.4 to 23 m². Its compact construction facilitates operation in locations where using a heavier roadheader would be economically unjustified or difficult due to limited space.

The transverse cutting head can be driven by a motor rated at between 100 and 132 kW. The parameters of the cutting unit allow the machine to cut rock with a compressive strength of up to 80 MPa. Actual performance depends on factors such as the properties and abrasivity of the rock, the condition of the cutting picks, the organisation of muck haulage and the conditions at the working face.

The MR50 can operate in workings with longitudinal gradients of up to ±18° and transverse gradients of up to 5°. Its compact construction and crawler travel system facilitate manoeuvring and precise positioning of the machine in relation to the working face.

The modular design allows the main assemblies to be transported separately and then connected efficiently underground. This solution is particularly important in mines and tunnels where the dimensions of shafts, haulage roadways or access routes restrict the transport of a fully assembled machine.

Applications of the MR50 roadheader

The MR50 can be used in both mining and tunnelling projects. Its construction is particularly well suited to applications requiring a compact, manoeuvrable and cost-effective machine for mechanical rock excavation. Typical applications of the MR50 include:

• driving underground mine roadways,
• excavating haulage and ventilation roadways,
• constructing development and access workings,
• excavating chambers and technical workings,
• mechanical excavation of small- and medium-sized tunnels,
• constructing underground infrastructure openings,
• cutting rock with a compressive strength of up to 80 MPa,
• working in locations with limited manoeuvring space,
• projects where compact dimensions and efficient machine transport are essential.

Depending on the ordered configuration and scope of certification, the MR50 can be prepared for the conditions present in a specific mine or tunnel. The final specification of the electrical, protection, water spraying and control systems is established according to the requirements of the individual project.

The MR50 has a modular construction that integrates the assemblies responsible for rock cutting, gathering and conveying muck, machine travel, power supply and control. Its compact design ensures good manoeuvrability and facilitates operation in workings with limited dimensions. Dividing the machine into principal modules simplifies transport, assembly and disassembly. The construction also provides access to the most important service points, facilitating maintenance and servicing.

MR50 cutting unit

The machine’s main working assembly is a transverse cutting unit comprising two cutterheads. It separates the rock from the solid face and forms the required excavation cross-section. The diameter of the cutting unit measured over the pick tips is approximately 750 mm, while its working width is approximately 1,230 mm. The cutterheads are equipped with tangential-rotary picks whose configuration can be adapted to the properties of the rock being cut. The 100–132 kW drive works with a gearbox that provides a cutting speed of approximately 2.51 m/s.

Cutting boom and head positioning mechanism

The cutting head is mounted on a pivoting boom connected to a positioning mechanism. The hydraulic system guides the cutting unit in the vertical and horizontal planes. Movement of the boom allows the required excavation profile to be formed and provides a cutting cross-section of up to 16.4 or 23 m², depending on the selected machine specification. The slewing mechanism connects the main structural sections and transfers the loads generated during cutting. The appropriate rigidity of this assembly ensures stable guidance of the cutterheads in relation to the working face.

Loading apron and gathering arms

Rock cut by the cutting head is directed onto the loading apron. Its standard width is approximately 2,000 mm. Suitable extensions can increase the width to approximately 2,500 or 3,000 mm, allowing the material collection area to be adapted to the excavation geometry. The gathering arms move the rock towards the centrally positioned conveyor. Efficient interaction between the loading apron, gathering mechanism and conveyor allows muck to be removed continuously from the cutting area.

Scraper conveyor

The scraper conveyor runs through the central section of the roadheader. It collects material from the loading apron and transports it towards the rear of the machine, from where it can be transferred to the next component of the haulage system. The system consists of a chain, scrapers, drive unit and guide trough, among other components. Its correct operation directly affects the continuity of muck removal and the efficiency of the entire excavation process.

Main frame and modular construction

The main frame connects the most important MR50 assemblies and transfers the loads generated during cutting, loading and machine travel. The modular division of the construction allows the main components to be transported separately. This enables the roadheader to be delivered to its operating site through roadways and haulage routes with limited dimensions and then assembled underground.

Crawler travel system

The crawler undercarriage allows the MR50 to travel and be positioned precisely in relation to the working face. The compact travel system supports manoeuvring in narrow workings. An appropriate crawler contact area helps limit specific ground pressure and provides machine stability during both travel and cutting.

Load Sensing hydraulic system

The hydraulic system controls functions including cutting boom movement, loading apron positioning and operation of the machine’s other mechanisms. The Load Sensing system adapts the hydraulic parameters to current demand. It provides precise control, reduces electricity consumption, lowers the oil temperature and limits loads on hydraulic components. The system can also power external hydraulic equipment provided for a particular specification, including the optional drilling and bolting unit.

Automatic central lubrication system

The central lubrication system automatically supplies lubricant to the machine’s most important lubrication points. It helps maintain suitable operating conditions for interacting components, simplifies maintenance and reduces the need for manual servicing.

Water spraying system

The water spraying system reduces the amount of dust generated during cutting. The MR50 can operate with an external water spray manifold or a system combining external spraying with internal sectoral after-tool spraying. The system configuration is selected according to the operating conditions and requirements of the intended site.

Electrical and control system

The electrical system supplies power to the cutting head motor, auxiliary drives, lighting, monitoring equipment and control components. The installation is adapted to the supply voltage and requirements applicable at the machine’s operating site. The control system enables operation of the roadheader’s main functions and monitoring of selected parameters. The scope of protection and monitoring functions is defined for the specific MR50 configuration.