The head assembly of an underground belt conveyor is the main drive and discharge section of the conveying system. It generally consists of a head frame, drive motor, gearbox, coupling, drive pulley, discharge arrangement, and associated safety protection components. Its main functions are to provide the power required to move the conveyor belt and to discharge material from the conveying line.
The configuration of an underground belt conveyor head depends on the required throughput, conveying distance, roadway conditions, belt tension, and drive power. Based on the number of drive pulleys, the main configurations include single-pulley, dual-pulley, and multiple-pulley drives. Based on the location of the drive units, they can be arranged as head drives, head-and-tail drives, or intermediate drives. The head frame itself may use an integral, modular, or skid-mounted structure to suit underground transportation and installation requirements.
These configurations differ in driving capacity, structural arrangement, installation space, and maintenance requirements. The appropriate design should be selected according to the operating conditions of the complete conveying system.
Types of Head Assemblies by Number of Drive Pulleys
Single-Pulley Drive
A single-pulley drive uses one drive pulley to move the conveyor belt. It is a relatively simple drive arrangement.
The main components include an electric motor, gearbox, coupling, drive pulley, and head frame. The motor supplies power through the gearbox, which reduces the output speed and increases torque. The coupling transfers the power to the drive pulley. Friction between the drive pulley and the conveyor belt then moves the belt along the conveying route.
Main features:
Simple structure: The drive system has fewer pulleys and a relatively straightforward transmission arrangement, making installation and routine maintenance easier.
Relatively compact layout: Compared with multiple-pulley drives, a single-pulley configuration generally requires less space for pulley installation.
Suitable for low to medium drive power requirements: It can be used when the conveying distance, throughput, and running resistance remain within the design capacity of the equipment.
Convenient maintenance: The smaller number of transmission components makes it easier to inspect the drive pulley, bearings, coupling, and gearbox.
The driving capacity of a single-pulley arrangement depends on the friction conditions between the pulley and belt, the wrap angle, belt tension, and drive power. For long conveying distances, high throughput, or high running resistance, a single-pulley drive may not provide sufficient traction. Dual-pulley or multiple-pulley configurations may need to be considered.
Dual-Pulley Drive
A dual-pulley drive uses two drive pulleys to transmit power to the conveyor belt. By adding another drive pulley and distributing the driving force between the two, this arrangement can meet higher power requirements.
A common configuration places two drive pulleys in the head area, with each pulley connected to its corresponding drive unit through a gearbox and transmission components. The pulleys may be arranged in tandem or in another configuration determined by the equipment design. Both pulleys contribute to driving the belt at different contact points.
Main features:
Higher driving capacity: Two drive pulleys share the power transmission load.
Improved traction conditions: Proper pulley arrangement and belt wrap angles can increase the available traction.
Suitable for higher conveying loads: This configuration can be used for mining conveyors with longer conveying distances, higher throughput, or greater running resistance.
More demanding drive coordination: The two drive pulleys must distribute power appropriately to avoid abnormal belt tension caused by speed or torque mismatches.
A dual-pulley drive does not necessarily require two electric motors. The number of drive units, gearbox configuration, and power transmission arrangement depend on the equipment design.
When two separate motors drive the pulleys, startup sequence, power balance, and dynamic belt tension must also be considered. Uneven load distribution between the drive units can affect belt operation.
Multiple-Pulley Drive
Multiple-pulley drives are generally used in conveying systems with high power requirements or substantial traction demands. Several drive pulleys contribute to power transmission, with the load distributed according to belt tension and the running resistance of the conveyor.
These systems may use combinations of multiple drive pulleys, gearboxes, and electric motors. The drive units can be arranged within one drive station or distributed according to the overall conveyor design.
Main features:
Flexible power configuration: Multiple drive units can be arranged to meet the total power requirements of the conveying system.
Suitable for high traction demands: Proper power distribution can meet the operating requirements of large mining conveyors.
More complex drive design: The speeds, torque outputs, and startup and shutdown sequences of the drive units must be coordinated.
Higher maintenance requirements: Multiple drive units, couplings, gearboxes, and pulleys require regular inspection. Maintenance must also account for the interaction between the different drive units.
Multiple-pulley drive systems require traction and belt tension calculations. They should also be checked under different operating conditions, including startup, braking, and variable loading. Adding more pulleys alone does not guarantee that the required driving capacity will be achieved.
Types of Drive Arrangements by Drive Unit Location
In addition to the number of drive pulleys, underground belt conveyors can be classified according to the location of their drive units along the conveying route.
This classification describes the drive arrangement of the complete conveyor rather than only the pulley configuration inside the head assembly.
Head Drive
A head drive arrangement concentrates the main drive unit at the head of the conveyor. The drive pulley in this section provides the power needed to move the entire belt.
This arrangement has a relatively centralized layout. The drive equipment and control components are mainly installed near the head, making centralized operation and maintenance more convenient.
Main features:
The drive units are concentrated in one area, simplifying the overall drive arrangement.
Sufficient installation and maintenance space must be provided for the motors, gearboxes, and pulleys at the head.
It is suitable when the head drive can provide sufficient traction for the entire conveying route.
For long conveyors or systems with high running resistance, belt tension and drive capacity at the head require careful evaluation.
Head drives are commonly used in mining belt conveyors. Whether a single-, dual-, or multiple-pulley configuration is required depends on the system parameters.
Head-and-Tail Distributed Drive
A head-and-tail distributed drive places drive units at both ends of the conveyor. The drive units at the head and tail work together to supply the required conveying power.
Compared with concentrating all driving force at the head, this arrangement can change the belt tension distribution along the conveying route, allowing different drive locations to share the running resistance.
Main features:
Driving power is distributed between different positions along the conveyor.
The drive load can be allocated according to system requirements, making the arrangement suitable for certain long-distance or high-throughput applications.
The head and tail drives must operate in coordination to prevent speed mismatches and belt tension fluctuations.
The installation layout and maintenance plan must account for the space and access requirements of both drive locations.
The number of pulleys and motors at the head and tail is not fixed. For example, a system may use a dual-pulley head drive together with a single-pulley tail drive, or another combination suited to the design.
Intermediate Drive
An intermediate drive adds a drive unit at a position between the head and tail of the conveyor. This allows power to be supplied at an additional point rather than relying entirely on the head or tail drive.
For underground conveying systems with long routes, high throughput, or demanding belt tension requirements, an intermediate drive may be considered based on engineering calculations. It can take on part of the traction demand along the conveyor.
Main features:
Additional power can be supplied at an intermediate position along the conveying route.
It helps adjust the belt tension distribution along the conveyor.
It can be combined with head and tail drives according to the system design.
Installation space, power coordination, and maintenance access must be considered.
An intermediate drive is not necessarily a separate type of head assembly. It is a drive arrangement for the complete belt conveyor. For long-distance underground systems, the decision to use an intermediate drive should take into account roadway conditions, belt strength, drive power, and running resistance.
Types of Head Frames by Structural Design
Underground roadways often have limited space. Conveyor equipment must pass through roadways, transport routes, and installation chambers before assembly. The head frame must therefore provide adequate support for the drive components while also allowing for transportation, installation, dismantling, and maintenance.
Common head frame designs include integral, modular, and skid-mounted structures.
Integral Head Frame
An integral head frame is generally a welded steel structure made from sections or plates. The drive pulley, bearing housings, and associated drive components are mounted on the same frame.
This arrangement has relatively few structural connections and provides good overall rigidity. It is suitable for fixed conveyors where transportation and installation space are sufficient.
In underground applications with narrow roadways or difficult transportation conditions, the overall dimensions of an integral frame may make handling and installation more difficult.
Modular Head Frame
A modular head frame consists of several separate structural sections connected during installation. The components can be transported into the mine individually and assembled underground.
Main features:
Convenient transportation: Separating the frame into smaller sections reduces the size of individual components and makes transportation through underground roadways and chambers easier.
Simpler site assembly: The modules can be installed in the specified sequence, reducing the difficulty of lifting and positioning a large integral structure.
Convenient maintenance and replacement: Some sections can be dismantled independently, making local repairs or equipment modifications easier.
The connections between frame sections must have sufficient strength and assembly accuracy. Loose connections or structural misalignment can affect the mounting position of the drive pulley.
Skid-Mounted Head Frame
A skid-mounted head frame is mainly used for belt conveyors that need to be moved or repositioned. The bottom of the frame has skid structures that allow the equipment to be moved as a complete unit using a towing system or another suitable method.
This design is used in some conveying systems that need to move as the working face advances or as the production layout changes. The frame must provide sufficient strength and stability both during normal operation and while being moved.
A skid-mounted head frame is not a standard configuration for every fixed underground belt conveyor. Its suitability depends on whether the equipment needs to be relocated and on the site transportation conditions.
Factors to Consider When Selecting an Underground Belt Conveyor Head
Different head configurations have different drive capacities, space requirements, and maintenance needs. Selection should be based on the operating conditions of the complete belt conveyor rather than the head structure alone.
Throughput and conveying distance
Determine the required conveying capacity, conveying distance, and operating hours. Higher throughput and longer conveying distances generally increase the running resistance that the drive system must overcome. Drive power and pulley configuration should be determined through engineering calculations.
Belt tension and driving capacity
The traction capacity of the drive pulley should be checked against belt strength, pulley wrap angle, friction conditions, and the tensioning arrangement. For high-power underground conveyors, the suitability of dual-pulley or multiple-pulley drives should also be evaluated.
Roadway space and installation conditions
The width, height, and cross-sectional shape of the underground roadway affect the arrangement of the head frame and drive equipment. Sufficient space must be provided for motors, gearboxes, brakes, pulleys, and maintenance access. Modular frames may be preferable where transportation is difficult.
Conveyor route inclination
Uphill and downhill conveyors have different drive and braking requirements. For uphill conveyors, the risk of belt reversal and material rollback after stopping must be considered. Downhill conveyors may require braking systems and provisions for regenerative operation. The required braking and anti-reversal arrangements depend on the route inclination and actual operating conditions.
Safety protection and maintenance requirements
Underground conveyor heads should be equipped with protective devices according to applicable mine safety requirements and the site risk assessment. Depending on the application, these may include anti-slip, plugged chute, belt misalignment, temperature, smoke, and other monitoring devices.
Main conveying routes also require attention to belt tension monitoring, belt rip protection, and guards around drive components.
The installation and removal space for motors, gearboxes, couplings, and braking equipment should also be considered so that components can be inspected, repaired, and replaced when necessary.
Custom Machining for Underground Belt Conveyor Components
An underground belt conveyor head contains various load-bearing structural components and precision mechanical parts, including drive pulley shafts, bearing housings, gearbox mounting bases, motor brackets, coupling connectors, pulley support plates, and head frame connectors.
The dimensional accuracy, shaft and bore positions, structural strength, and assembly fits of these components affect drive installation, pulley alignment, and the operating stability of the conveyor.
Hansheng Automation provides CNC precision machining of non-standard metal components according to customer-supplied engineering drawings. These services support structural and transmission components used in underground belt conveyors and other mining conveying equipment.
In addition to mining conveyor components, we also undertake custom machining of precision yacht parts, RC racing car parts, tobacco packaging machinery components, and filling machinery parts.
