Chain conveyors are robust conveying systems for continuous material transport in harsh environments. They move bulk materials, fragments, and components using one or more chain strands and dimensionally stable flights. In process chains around concrete demolition, special demolition, rock excavation, tunnel construction, and natural stone extraction, they ensure an orderly material flow—for example, when, after loosening with hydraulic wedge splitters or pre-crushing with concrete pulverizers, material must be transported to screens, crushers, sorting stations, or intermediate hoppers. The systems are designed for impact loads, abrasion, and varying particle-size distributions and can be powered electrically or hydraulically, for example via hydraulic power packs, when mobile or remote drives are required.
Definition: What is meant by chain conveyors
A chain conveyor is a conveying system in which an endless chain (or multiple chain strands) serves as the traction element. Flights, scrapers, or hinge plates are attached to the chain, transporting the conveyed material in a trough, on a track, or over inclines. Typical variants include trough or drag chain conveyors for bulk materials, hinge-plate chain conveyors for coarse or hot material, and two-strand chain conveyors with crossbars for heavy unit loads. Chain conveyors are characterized by high impact resistance, defined metering, and large incline angles, and are used wherever conveyor belts reach their limits—such as with abrasive, hot, angular, or strongly varying materials.
Functional principle and main components
The basic principle is a driven chain loop that runs in a closed or open trough. The chain pulls flights that pick up, push, or scrape the material. The drive and return stations form the ends of the conveying route; a tensioning station maintains the necessary chain pre-tension. Wear strips and linings protect the trough; covers minimize dust and prevent reaching into moving parts.
Typical designs
- Drag or trough chain conveyors: Closed trough with scrapers for bulk materials, moist or dusty materials, and for construction debris with fines.
- Hinge-plate chain conveyors: Hinge plates on chain strands for coarse, hot, or oily pieces, suitable for sharp-edged concrete pieces and steel remnants.
- Two-strand chain conveyors with flights: For heavy components, blocks, and slabs with defined indexing.
- Vertical chain conveyors and bucket solutions: For steep or vertical conveying when geometry requires it.
Central assemblies
- Drive station with gear motor or hydraulic drive (supplied e.g., via hydraulic power packs), chain sprockets, and torque monitoring.
- Chain strands, chain pins, and flights/scrapers; chain grade and pitch matched to load, temperature, and abrasiveness.
- Trough and wear lining (Hardox, plastic, cast material) to reduce friction and abrasion.
- Return and tensioning station (spindle, weight, or spring tensioning) for constant chain tension.
- Infeed and discharge chutes, dust covers, inspection openings, and service hatches.
- Sensors: level, speed and standstill monitors, chain misalignment, temperature, and drive monitoring.
Fields of application in demolition, tunnel construction, and quarrying
In the application areas relevant to Darda GmbH, chain conveyors handle the orderly removal, buffering, and metering of materials. They connect operations such as splitting, cutting, or size reduction with subsequent process steps such as screening, sorting, or loading.
Concrete demolition and special demolition
During the deconstruction of concrete structures, heterogeneous material streams arise: concrete pieces, mortar, masonry, reinforcing steel. After pre-crushing with concrete pulverizers or controlled splitting with hydraulic wedge splitters, chain conveyors transfer the material in an impact-tolerant manner. Hinge-plate chain conveyors can handle angular chunks and also take mixed-in steel, which is later separated and, if necessary, further downsized with steel shears or Multi Cutters. Trough chain conveyors are helpful with dusty or moist fractions because they operate enclosed.
Strip-out and cutting
In strip-out work inside buildings, a wide variety of materials arise in confined spaces. Compact chain conveyors with low overall height are suitable for conveying parts from cutting processes—such as from combination shears or Multi Cutters—onto containers. Plate-like pieces from trimming tanks and vessels can be discharged safely on hinge-plate chain conveyors after the use of tank cutters.
Rock excavation and tunnel construction
Underground, robust, low-maintenance solutions are required. Drag chain conveyors are used as pre-conveyors when rock is hauled away after controlled loosening with rock splitters. Steep ramps, varying particle-size distributions, and moisture make a case for chain conveyor technology. Closed troughs reduce dust and facilitate the material flow to intermediate bunkers or downstream conveyors.
Natural stone extraction
In quarries, blocks, cut-offs, and breakage must be moved in an orderly manner. Two-strand chain conveyors with flights convey heavy pieces with minimal slip. After controlled splitting with hydraulic wedge splitters, defined batches can be fed to saws, crushers, or classification plants.
Special applications
In particularly harsh applications—high temperatures, heavy contamination, and sparks—chain conveyors play to their strengths. Impact-resistant hinge plates and heat-resistant linings enable safe operation, for example in thermally influenced cutting processes or in temporary construction-site setups.
Design: sizing, performance, and interfaces
Sizing is based on conveying capacity, bulk density, particle-size distribution, temperature, moisture, abrasiveness, and the required incline angle. Decisive parameters are chain pitch, flight spacing, trough width, chain speed, and drive power. For impact-loaded streams from demolition or splitting processes, generous sizing of the infeed section and wear linings is advisable. Interfaces to screens, crushers, magnetic separators, and bunker dischargers are designed to avoid bridging and backflow.
Material flow with hydraulic work tools
When upstream stages operate with hydraulic tools—such as concrete pulverizers, steel shears, or Multi Cutters—coordinated cycling is advantageous. Chain conveyors can be synchronized with the work tool via frequency- or flow-controlled drives (electric or hydraulic via hydraulic power packs). Torque monitors, level sensors, and start/stop logic limit overfilling and help avoid blockages.
Advantages and limitations compared with conveyor belts
- Advantages: Very robust under impact loads and sharp edges; large incline angles possible; suitable transport of hot, oily, or moist materials; defined metering; enclosed design for dusty conveyed goods.
- Limitations: Higher noise levels; chain and flight wear; greater maintenance effort (lubrication, tension readjustment); shorter economical conveying lengths and speeds than with conveyor belts.
Safety, health, and environment
For safe operation, covered hazard points, effective emergency stops, access regulations, and clear operating instructions are essential. In combination with cutting or splitting work tools, the hazard zone must be coordinated to avoid pinch and in-draw points. Dust and noise reduction is achieved through encapsulated troughs, extraction points, and suitable linings. Depending on the environment, requirements for the avoidance of ignition sources and explosion protection may be relevant. Legal requirements regarding machine safety, occupational safety, and emission limitation must be observed depending on site and application; implementation follows the applicable rules and standards.
Maintenance, lubrication, and typical wear patterns
Regular inspections extend service life and secure availability. Especially in demolition and stone operations, abrasive loads act on the chain, sprockets, flights, and trough. Demand-oriented lubrication and correct chain tension reduce elongation and impact loads. Condition data such as motor current, speed, and temperature facilitate predictive maintenance.
- Weekly: Visual check for loose flights, uneven running, build-up in the trough, seals, and covers.
- Monthly: Measure chain elongation, readjust chain tension, check lubrication points, inspect linings.
- Quarterly: Check sprockets and bearings, test sensors, verify emergency-stop functionality.
- Event-driven: After blockages or severe impact events, inspect flights, pins, and trough running surfaces.
Integration into process chains of deconstruction and recycling
In the process chain, chain conveyors take on functions such as buffering, metering, de-dusting, and distribution to multiple lines. After reducing piece sizes with concrete pulverizers or splitting in a defined way with hydraulic wedge splitters, they route material to pre-screens. Diverted reinforcing steel is conveyed via separate conveyors to steel shears or Multi Cutters. Plates or shells from apparatus and vessel deconstruction are transferred with low impact after the use of tank cutters. This creates a continuous, controlled material flow that avoids downtime and feeds downstream units evenly.
Selection criteria and planning checklist
- Conveyed material: particle sizes, shape, bulk density, moisture, temperature, abrasiveness, steel content.
- Capacity and route: t/h, conveying length, difference in elevation, incline angle, infeed and discharge geometry.
- Robustness: flight design, trough lining, impact and wear protection, chain pitch.
- Drive and control: electric or hydraulic (hydraulic power packs), controllability, interfaces to upstream devices (e.g., concrete pulverizers).
- Maintenance: accessibility, lubrication concept, tensioning system, condition monitoring.
- Environment and occupational safety: dust encapsulation, noise control, fire protection, cleaning options.
- Mobility and installation: stationary, modular, mobile; overall height and space requirements in existing plants.
Examples of typical process steps
- Concrete demolition and deconstruction: pre-crushing with concrete pulverizers – discharge onto hinge-plate chain conveyor – pre-screen – steel separation – transfer of steel to steel shears – mineral fraction to crusher/screen.
- Tunnel heading: loosening with rock wedge splitters – transfer to drag chain conveyor – intermediate bunker – further conveying – stockpile formation or removal.
- Natural stone: splitting with hydraulic wedge splitters – indexed conveying of large pieces via two-strand chain conveyor – feeding saws – discharge of remnants and fines.
- Industrial deconstruction: cutting tanks with tank cutters – plate discharge onto hinge-plate chain conveyor – sorting – downsizing with Multi Cutters – container loading.
Terms and distinctions in conveying technology
Depending on the design, chain conveyors include drag and trough conveyors, hinge-plate chain conveyors, and vertical chain solutions. They differ from conveyor belts by the traction element (chain instead of belt) and by the flight principles. Compared with screw conveyors, they offer advantages with coarse and heterogeneous materials. In process chains of demolition and natural stone extraction, they are a proven complement to cutting and splitting tools such as concrete pulverizers, Multi Cutters, or hydraulic wedge splitters, because they carry the resulting material flow forward in a controlled, impact-resistant manner.