In the design and operation of bulk material handling systems, whether for new projects or retrofits, customers face a series of specific and critical technical and commercial decisions. Drawing on global project experience, ZOOMRY has compiled the most concerned questions about belt conveyors into a series of FAQs, providing you with clear, professional guidance with an international perspective. A FAQ table is attached at the end for direct jump preview.

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I. What are the mainstream soft start methods for belt conveyors?

Soft start methods are mainly divided into two categories: mechanical and electrical. Mechanical types include hydraulic couplings, permanent magnet couplings, and Controlled Start Transmission (CST); the electrical type mainly refers to Variable Frequency Drive (VFD).

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II. What are the characteristics and applicable scenarios of hydraulic couplings, permanent magnet couplings, and CST?

• Hydraulic Coupling: Transmits power through hydraulic oil to achieve flexible start-up within a limited range and overload protection. It is technically mature, simple in structure, low in cost, and easy to maintain, but has slip loss and limited soft start performance. It is usually suitable for belt conveyors with small power (e.g., below 500kW), short distance, and low requirements for start-up curves.
• Permanent Magnet Coupling: Transmits torque through the magnetic field between permanent magnets to achieve contactless soft start. It is maintenance-free, allows large alignment errors, and has no risk of medium leakage, with slightly better soft start performance than hydraulic types. However, it also has the problems of narrow speed regulation range and inability to achieve power balance, making it suitable for medium-power occasions requiring environmental isolation or simplified maintenance.
• CST (Controlled Start Transmission): A precision hydraulic-mechanical combined drive system that achieves stepless speed regulation and smooth start-up through hydraulically controlled clutch plates. It can provide extremely precise torque control, excellent soft start/stop curves, and outstanding multi-machine power balance capability. However, its system is extremely complex, initial investment is high, and it has extremely high requirements for hydraulic oil cleanliness and maintenance professionalism. It is usually only used in extra-large, critical conveying systems with extreme requirements for start-up dynamic performance (such as main shaft hoisting belts), and has a relatively narrow market application.

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III. Why is Variable Frequency Drive (VFD) recommended for long-distance, high-power conveyors?

Variable frequency drive has become the standard configuration for modern large and medium-sized, high-performance belt conveyors due to its unparalleled comprehensive advantages:

• Excellent Start-up Control: Programmable S-curve speed profiles minimize impact and dynamic tension during start-up/shutdown, protecting the belt and mechanical structure.
• Precise Torque Control: Achieves constant torque start-up, effectively preventing belt slipping, and realizes high-precision power balance among multiple drive units, extending equipment life.
• Speed Regulation and Energy Saving: Can flexibly adjust belt speed according to actual conveying capacity to achieve energy-saving operation. In downward conveying power generation conditions, four-quadrant VFD can convert potential energy into electrical energy and feed it back to the power grid.
• High Power Adaptability: Covers an extremely wide power range, easily meeting the drive needs of hundreds of thousands of kilowatts.
• Intelligent Integration: Easy to connect to the plant-wide DCS/PLC system for intelligent control and monitoring. From the perspective of Total Cost of Ownership (TCO), its energy-saving benefits and reduced maintenance costs make it often more economical in large-scale projects.

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IV. Is the post-maintenance of the belt conveyor system difficult? What if the user lacks experience?

A well-designed and high-quality belt conveyor system does not require heavy daily maintenance. The core lies in establishing and implementing a scientific preventive maintenance system.

To address the issue of users lacking experience, ZOOMRY provides systematic support during the project handover phase:

1. Free Professional Technical Training: After the completion of equipment installation and commissioning, we will provide customized training for the owner's operation and maintenance team, including:
   • System safety operation procedures.
   • Items, standards, and cycles for daily inspections and regular maintenance (such as drum bearing temperature rise, idler rotation flexibility, cleaner wear inspection, etc.).
   • Rapid diagnosis and handling processes for common faults (such as belt deviation, material spillage, abnormal noise, etc.).
   • Replacement steps and safety precautions for key spare parts (such as idlers, bearings, scrapers, lubricants).
2. Comprehensive Document Support: Including detailed maintenance manuals, lubrication charts, spare parts lists (with part numbers), and wear parts replacement cycle tables.
3. Global Service Network Support: We provide remote technical consulting and rapid on-site service response to ensure users receive timely support when encountering complex problems.

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V. What is the normal service life of Conveyor idlers?

Idler service life is a key indicator of conveyor quality and operating costs. Chinese National Standard (GB/T 10595) requires that the service life of idlers under rated conditions shall not be less than 25,000 hours, and the failure rate within the service life shall not exceed 10%.

ZOOMRY's idlers adopt high standards from the design stage: selecting special bearings with large internal clearance and long service life, equipped with multiple labyrinth seals and long-acting lithium-based grease, and the rollers undergo precision processing and dynamic balance verification. In actual projects, the average design life of our idlers generally exceeds 50,000 hours (about 5-7 years of continuous operation), with an extremely low failure rate under standard operating conditions, significantly reducing users' long-term replacement costs and downtime risks.

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VI. What is the usual warranty period for Conveyor Belts? Can it be extended?

The industry's usual warranty period for conveyor belts is 12 months from the date of commissioning. This is a basic guarantee based on material fatigue and wear characteristics.

ZOOMRY understands that the conveyor belt is a core asset of the system, and its service life is closely related to system design, material characteristics, operating tension, etc. Therefore, on the basis of providing a standard 12-month warranty, we can provide customers with a more competitive extended warranty plan based on detailed working condition analysis (such as material abrasiveness, maximum particle size, working tension curve, ambient temperature, etc.), with the warranty period extendable to 2 years, 3 years or even longer. This reflects our deep confidence in the overall system matching and product quality.

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VII. Will an inclined belt conveyor reverse when suddenly powered off? How to prevent it?

Yes, it will be an extremely dangerous situation if no protective measures are taken. The gravity of the materials on the inclined belt conveyor will generate a downward component force. Once the driving force disappears (such as power failure), the belt may reverse under the heavy pressure of the materials, leading to material accumulation, equipment damage, and even safety accidents.

The standard measure to prevent and control reversal is to install a backstop.

• Selection: During design, accurately calculate the required backstop torque according to the belt inclination angle, length, and conveying capacity, and select the appropriate specification of backstop accordingly.
• Installation Position: For small backstop torque, a backstop built into the reducer or installed on the high-speed shaft of the reducer can be used; for long-distance, large-capacity heavy-duty belt conveyors that generate huge backstop torque, large backstops must be selected and directly installed on the drive drum shaft.
• Operation and Maintenance: In operation, full-load shutdown with materials should be avoided as much as possible. In maintenance, it is necessary to regularly check the lubrication status of the backstop to ensure that its internal mechanism is flexible and reliable without jamming.

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VIII. How much power can a downward-inclined belt conveyor generate? How to handle this electrical energy?

When a downward-inclined belt conveyor is in operation, the potential energy of the materials drives the belt, turning the motor into a generator state.

• Power Generation Estimation: The generated power (P) is mainly determined by the formula P ≈ η * Q * H * g (η is efficiency, Q is mass flow rate, H is vertical drop height, g is gravitational acceleration). Simply put, the greater the downward drop height and conveying capacity, the greater the power generation. The selection of the motor and VFD must meet the power requirements of the power generation condition.
• Electrical Energy Handling Schemes:
  • Standard Scheme – Feed Back to Power Grid: Through a four-quadrant VFD, the generated clean electrical energy is inverted and fed back to the plant's power grid for use by other equipment. This is the most direct and efficient energy-saving method.
  • Energy Storage Scheme: In scenarios where the generated power is very large and the power grid cannot fully absorb it, or where there are peak and valley electricity prices, an economic benefit analysis can be conducted to consider configuring an energy storage system (such as a battery energy storage station) to store electrical energy and release it during electricity use, realizing optimal energy utilization.

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IX. What is the maximum climbing angle of a belt conveyor?

The maximum allowable inclination angle is mainly determined by the angle of repose, particle size, humidity of the materials, and the surface form of the belt.

• Upward Conveying Belt:
  • When conveying bulk materials such as raw coal and crushed stone, using a herringbone or diamond-shaped textured conveyor belt combined with a deep trough idler group (such as 45° or 60°), the maximum inclination angle can reach 28° to 33°.
  • When conveying materials with poor fluidity or easy rolling such as limestone and wet sticky coal, the maximum inclination angle is usually limited to 16° to 26°.
• Downward Conveying Belt: To prevent materials from continuing to slide due to inertia during emergency shutdown, its design inclination angle should be 2° to 5° smaller than the upward conveying angle of the same material, and it must be equipped with effective braking and control systems.

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X. What are the schemes for achieving long-span (such as crossing rivers and roads) conveying? What is the maximum span?

There are three main mainstream technical schemes, and their selection depends on span, terrain, investment, and maintenance costs:

• Long-Span Truss: The most common economical scheme, with a single-span usually between 60 meters and 80 meters. It has a solid structure and convenient maintenance, suitable for most conventional crossings.
• Suspension Bridge Structure: Taking load-bearing cables as the main force-bearing components, the conveyor belt is placed on them, with a single-span up to more than 200 meters. It has a lightweight structure, low steel consumption, and relatively low requirements for foundations, suitable for crossing canyons and large rivers.
• Cable-Stayed Bridge Structure: Supports the conveyor truss through towers and stay cables, with a single-span range of 100 meters to 200 meters. It has high structural stiffness, good operational stability, and excellent landscape performance.
• Decision Points: Long-span structures are technically very mature, and their main challenge lies in significantly increased investment costs. In route planning, avoiding ultra-long spans should be a priority; if unavoidable, a detailed technical and economic comparison must be conducted.

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XI. In EPC projects, how to divide the interface responsibilities for system power distribution?

Clear interface division is the key to the successful execution of the project. We usually provide two contract models for customers to choose from:

• Power-Taking Mode: The owner is responsible for leading the terminal blocks of 10kV high-voltage power supply and 380V/400V low-voltage power supply to the location specified by us. Starting from this terminal block, the design, supply, and installation of high-voltage switchgear, transformers, low-voltage distribution cabinets, drive control cabinets, and all connecting cables shall be the responsibility of us.
• Power-Supply Mode: The owner is responsible for directly laying and connecting the power supply (10kV or 400V) that meets the specifications to the upper port of the designated incoming line switch in our electrical room. Starting from the lower port of this incoming line switch, all power distribution and control equipment in the room and outgoing lines to on-site equipment shall be the responsibility of us.

Clearly adopting which mode can effectively define the scope of work of both parties and ensure seamless connection of on-site construction.

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Core Question Quick Reference Table

Question	Conclusion
Hydraulic/Permanent Magnet Coupling, CST, Variable Frequency Drive (VFD)	Choose VFD for long-distance, high-power, and high-requirement applications; CST for extreme working conditions; couplings can be selected for small-power and short-distance to control costs.
Preventive Maintenance, Technical Training	The system maintenance workload is manageable. We provide free in-depth training and full-cycle document support to empower the customer's team.
National Standard Benchmark: >25,000 hours	ZOOMRY idlers have a design life of over 50,000 hours, leading the industry in durability and reducing long-term TCO.
Industry Standard: 12 months	Extended warranty (up to 3 years or more) can be provided according to specific working conditions, reflecting system design confidence and quality commitment.
Backstop (High-Speed Shaft/Drum Shaft)	Must be installed and selected based on calculations. Avoid heavy-load shutdown during operation and regularly check lubrication.
Four-Quadrant VFD Feedback, Energy Storage System	Power generation is determined by drop height and conveying capacity. The preferred scheme is to feed back to the power grid; energy storage configuration can be evaluated when economically feasible.
Upward conveying of raw coal can reach 33°, downward conveying requires a smaller angle	The angle depends on material characteristics. Using textured belts and deep trough idlers can significantly increase the upward conveying angle.
Truss (≤80m), Suspension (≥200m), Cable-Stayed (100-200m)	Technically mature, with the core consideration being economy. Prioritize avoiding unnecessary long spans during planning.
Power-Taking Mode, Power-Supply Mode	Clearly defining the power supply responsibility division point in the contract is a key commercial clause to ensure the smooth execution of the project.