Overview
ISO 5048:1989 provides standardized methods for calculating the operating power required at the driving pulley of belt conveyors with carrying idlers, and for determining the tensile forces developed in the belt. It defines the required terms, symbols and units, classifies resistances to motion and gives formulae for driving force, power requirements, capacity and cross-section sizing for smooth, patternless belts. The standard targets conventional idler-conveyor systems and offers a practical (though not exhaustive) calculation method for design and specification.
Key Topics
- Scope and definitions: Clear definitions for terms such as surcharge angle, angle of repose and symbol conventions used throughout calculations.
- Resistances to motion: Classification into main (FH), secondary (FN), special main (Fsl), special secondary (Fs2) and slope resistances (Fst), with explanations of contributing effects (idler bearing friction, material acceleration at loading, chute friction, cleaners, etc.).
- Driving force and power: Formulae to sum resistances and compute peripheral driving force on the driving pulley and operating power (power = driving force × belt speed).
- Coefficients used in calculation:
- Artificial friction coefficient f - basic value 0.02 for many installations; guidance on adjustments (e.g., ~0.016 for well-aligned idlers, up to ~0.03 for poor alignment; downhill/braked conveyors example: ~0.012).
- Length-dependent coefficient C - used to simplify calculations for long conveyors (L > 80 m); recommended L0 (additional length) typically between 70 m and 100 m; C ≥ 1.02.
- Capacity and cross-section: Methods to calculate belt width and material cross-section for smooth patternless belts based on maximum capacity and particle size.
- Limitations: The standard is a simplified method; it does not cover complex arrangements such as multiple drives or undulating vertical profiles - expert consultation recommended for those cases.
Applications
ISO 5048:1989 is used by:
- Conveyor designers and mechanical engineers for preliminary and detailed design.
- Motor and drive specifiers to size driving motors and pulleys.
- Belt manufacturers and specifiers to determine required tensile strength and belt construction.
- Plant engineers and maintenance teams for troubleshooting and performance verification.
- Procurement and project managers for writing technical specifications and tender documents.
Practical benefits include consistent estimation of operating power, safer belt tension selection, correct belt width/capacity sizing, and improved component selection (idlers, pulleys, cleaners).
Related standards
- Prepared by ISO/TC 101 (Continuous mechanical handling). For comprehensive conveyor design, use ISO 5048 alongside other ISO/TC 101 documents and manufacturer guidelines covering complex drives, elevated profiles, and special belt types.
