Born underground

Longwall Mining Technology

Roof Supports

Customized Roof Support Systems

Steep grades, very thick and very thin seams, unstable roofs and massive sandstone plates, soft floor and geological faults. These varying conditions require a high level of adaptation to specific requirements. HBT roof supports are world-renowned for their reliability under the most extreme conditions. With superior availability and unparalleled quality in design and production, our roof supports set the standard in longwall mining.

State-of-the-art Technology

HBT is the world leader in longwall roof support technology. In the early 1970s, demanding mining conditions in German coal mines set the stage for extensive R&D in roof support technology. Steeply inclined coal seams both thick and thin, weak roofs and massive sandstone roofs, soft floors, and geological faults called for a high degree of customization. The resulting expertise has been deployed and applied to all mining areas of the world and provides ustomers with state-of-the-art technology customized to maximize control of the roof and floor of their longwalls. This not only eliminates downtime resulting from control of the strata surrounding the coal seam; but also facilitates automation of roof support systems, even in very difficult geological conditions.

Customized Design

Two-meter Roof Supports

The two meter (6.56 ft) wide roof support offers several advantages over conventional 1.50 or 1.75 meter (4.92 or 5.74 ft) wide shields. Fewer shields mean lower investment and less maintenance – and fewer parts to malfunction. Longwalls are easier to steer and relocation is done faster as there are fewer shields to move.

Seamless Range

A full range of roof supports are available for mining heights from 550 to 7500 mm (1.80 to 24.60 ft), with support capacities in excess of 1750 tonnes (1,929 tons). As with all HBT products, top quality and leading innovation result in products that deliver maximum performance and system availability, long service life, and lowest possible cost of ownership.

State-of-the-art Technology

HBT is one of the leading suppliers in longwall roof support technology. In the early 1970s, demanding mining conditions in German coal mines set the stage for extensive R&D in roof support technology. Steeply inclined coal seams both thick and thin, weak roofs and massive sandstone roofs, soft floors, and geological faults called for a high degree of customization. The resulting expertise has been deployed and applied to all mining areas of the world and provides customers with state-of-the-art technology customized to maximize control of the roof and floor of their longwalls. This not only eliminates downtime resulting from control of the strata surrounding the coal seam but also facilitates automation of roof support systems, even in very difficult geological conditions.

Control Systems

HBT manufactures a complete range of shield support control systems ranging from manual hydraulic controls to the highly acclaimed PMC-R electronic control system for the most advanced face automation and equipment monitoring.

The HBT PMC-R electro-hydraulic longwall face control system represents the cutting edge in longwall automation technology and facilitates full automation, monitoring and remote diagnostics for all face equipment. All information can be transferred to the surface in real time to allow maximization of longwall performance.

Test Process

The main tests involve longitudinal and lateral bending load and torsion loads in addition to compressive and tensile load. Tests are usually performed with up to 70,000 load cycles with 10% to 20% overload. Complete roof supports are tested as well as individual components such as base, canopy, legs, cylinders, controls, pressure relief valves and hoses.

Test measurements confirm calculations and allow constant product improvement and full exploitation of optimization and savings potential. Testing ensures that equipment is suitable for the intended use and will have a guaranteed service life as specified even under extreme conditions.

Legs and Cylinders

HBT legs and cylinders for hydraulic roof supports are designed and manufactured to the highest quality and performance standards. Double- and triple-stage systems are available with equal yield rating in all stages. Materials and designs are selected to ensure long service life. Plating is applied to meet the most corrosive environments.

Special Applications

HBT has extensive experience in the design of shield supports for specific mining conditions and for soft-rock longwall applications other than coal. Steep seam supports and supports with articulated fore pole extension canopies and high tip loads have been developed for extreme geological situations.

Conventional Sublevel Caving

Conventional sublevel caving supports allow coal to be drawn from the roof using articulated canopies with special chutes integrated into the gob shield, the front AFC or a second AFC located behind the shields. Many shield installations have been supplied to customers, particularly in central and eastern Europe.

Steep-seam Mining

Faced with the enormous reserves of high-quality coal blocked underground and the intensive look of many customers for promising solutions, we have developed and introduced various specific, state-of-the-art systems to also mine steeply inclined coal seams. HBT can offer tailor-made solutions for nearly all conditions, including particularly steep applications.

Longwall Top Coal Caving

The Longwall Top Coal Caving (LTCC) roof support allows mining to a total seam height of more than 10 m (33 ft) by using a longwall shearer to cut the bottom 2.8-3.0 m (9.2-9.8 ft) and then caving the top coal behind the roof supports onto a rear AFC. This type of longwall is in service for example at a mine in the Hunter Valley, Australia.

Engineering Excellence

HBT maintains extensive facilities for the design, testing and manufacture of its products. All engineering departments have powerful workstations with state-of-the-art engineering software to enable simultaneous stress analysis and cost effectiveness of design. Finite Element Analysis is used to meet fatigue life requirements of components and products.

Design Failure Mode and Effects Analysis is used to maximize reliability of all critical areas to eliminate the risk of in-service failure. Prior experience is used as a feedback process to capture relevant information from many different longwall operations to continuously upgrade product performance for the benefit of our customers.

This is invaluable for longwall projects where difficult geological conditions prevail. Cycle testing is a vital part of the design process. Our manufacturing facilities are continually upgraded to take advantage of developing technologies and techniques to achieve maximum quality at minimum cost.

Top Specs

Height (Extended)
1100-6100 mm / 43.3-240.2 in

Shield Centers
1500-2050 mm / 59-80.7 in

Shield Density
up to 111 tonne /m /2 12.5 ton/ft2

Example High Seam
Roof Support

Example Low Seam
Roof Support

Roof Support Specifications
Spec	Metric	Imperial
Height Closed	500-2900 mm	19.7-114.2 in
Height Extended	1100-6100 mm	43.3-240.2 in
Shield Centers	1500-2050 mm	59-80.7 in
Nominal Leg Forces	2 × 800-2 × 7156 kN	2 × 90-2 × 805 ton
Shield Density	up to 111 tonne/m2	up to 12.5 ton/ft2
Hydraulic Leg	up to 500 mm	up to 19.7 in
Canopy	Rigid design (with telescopic flipper)
Canopy Length	2997-8000 mm	118-315 in
Forepole Length	1980-4520 mm	78-178 in
Rear Projection	850-1448 mm	33.5-57 in
Base	Split design OR rigid design with telescopic relay bar/pusher cylinder
Relay Bar Direct Mounted OR Reverse Mounted	650-1067 mm effective web	25.6-39.4 in effective web
Shifting Cylinder (with Reedrod)	700-1080 mm	27.6-42.5 in
Shield Pull Force	185-565 kN/ 315/320/350 bar	20.7-63.3 ton/ 4568/4640/5076 psi
Conveyor Push Force	89-815 kN/ 315/320/350 bar	10.0-91.5 ton/ 4568/4640/5076 psi
Side Seals – on Canopy, Caving Shield (and rear lemniscates) Both Sides Fixed/One Side Fixed, One Side Movable, Rehandable/Not Rehandable	up to 300 mm stroke	up to 11.8 in stroke
Materials	High strength steel
Test	EN 1804, different test program with up to 90,000 cycles
Weight	6.5-63.5 tonne	7.15-70 ton

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Customized Roof Support Systems

State-of-the-art Technology