ISO 5048 Belt Conveyor Calculator — Drive Power & Tensile Forces
ISO 5048 — Continuous mechanical handling equipment — Belt conveyors with carrying idlers — Calculation of operating power and tensile forces
ISO 5048:1989 is the international standard for calculating the operating power and tensile forces in belt conveyors with carrying idlers. It defines the resistance method — splitting total drive resistance into the primary (main) running resistance F_H, the secondary resistance F_N via the length factor C, and the material-lift resistance F_St — and then derives the belt tensions at the drive pulley using the Euler belt-friction equation. The result is the shaft power, motor input power and the tight-side and slack-side belt tensions needed to select the motor, belt carcass and take-up system.
ISO 5048 is the standard cited in bulk-materials handling, mining and process-plant conveyor design when a reviewer or a procurement specification calls for a documented, standard-based analysis. MechanixCalc implements ISO 5048 directly in the browser, combining the core capacity and power method with the DIN 22101 equal-roll troughed cross-section geometry and the CEMA minimum-sag tension criterion, and generates a shareable PDF engineering report with the full method and worked numbers.
Calculators that implement ISO 5048
What ISO 5048 covers
- Main running resistance F_H — rolling friction of carry and return idlers, belt bending and material flexure along the full conveyor length
- Secondary resistance F_N — loading-chute, pulley-bearing, belt-cleaning and skirtboard forces, captured by the ISO 5048 length factor C from Table 2
- Incline/decline lift resistance F_St — net material-weight component along the slope (belt weight cancels in a closed loop)
- Total effective pull F_U = C·F_H + F_St and the resulting shaft power and motor input power
- Drive-pulley belt tensions T₁ (tight side) and T₂ (slack side) from the Euler friction equation for the specified wrap angle
- Minimum carry-run tension from the 1.5 % belt-sag criterion (DIN 22101 / CEMA) and take-up travel from belt elongation (ISO 9856 per-unit-width modulus)
Governing formulas
F_H = f · L · g · (q_RO + q_RU + (2·q_Belt + q_G)·cos δ); F_U = C · F_H + F_St; F_St = q_G · H · gwhere f = artificial friction coefficient (ISO 5048; typically 0.016–0.030); L = conveyor centre-to-centre length (m); g = 9.81 m/s²; q_RO, q_RU = rotating idler mass per metre on carry and return runs (kg/m); q_Belt = belt mass per metre (kg/m); q_G = material load per metre (kg/m); δ = incline angle; C = secondary-resistance length factor (ISO 5048 Table 2); H = lift height (m); F_St = lift resistance (N)
P_shaft = F_U · v [W]; P_motor = P_shaft / (1000 · η) [kW]where v = belt speed (m/s); η = drive-train efficiency (gearbox + coupling; typically 0.93–0.97)
T₁ / T₂ = e^(μ·α); T₁ = F_U · e^(μα) / (e^(μα) − 1); T₂ = T₁ − F_Uwhere μ = rubber-to-steel friction coefficient (≈ 0.35 clean dry); α = wrap angle on drive pulley (rad); T₁ = tight-side tension (N); T₂ = slack-side tension (N)
Frequently asked questions
What is ISO 5048 used for?
ISO 5048 is the international standard for calculating the operating power and tensile forces in belt conveyors with carrying idlers. It provides the resistance method — splitting total drive resistance into the main running resistance F_H (proportional to conveyor length) and secondary resistances captured by the length factor C — and derives the drive shaft power and the belt tensions at the head pulley. It is the standard cited in mining, bulk-materials handling and process-plant conveyor specifications when a documented, auditable design basis is required.
What is the ISO 5048 length factor C and how is it applied?
C is the secondary-resistance correction factor from ISO 5048 Table 2. It accounts for loading-chute impact, pulley bearing friction, belt-cleaning scrapers and skirtboard drag — forces that are roughly constant regardless of conveyor length. The total effective pull is F_U = C·F_H + F_St, so secondary resistances = (C − 1)·F_H. Short conveyors (< 50 m) carry a large overhead — C can reach 2.1–3.6 — so omitting it significantly under-sizes the drive. For long conveyors (> 1 000 m) C approaches 1.05 and secondary resistances become a minor fraction of the total.
How do ISO 5048, DIN 22101 and CEMA relate to each other?
ISO 5048 governs the resistance calculation and drive power — it is the international reference standard. DIN 22101 is the German national standard covering the same scope and extends ISO 5048 with detailed cross-section geometry for troughed idlers and additional guidance on belt-safety factors. CEMA (Conveyor Equipment Manufacturers Association, 7th edition) is the North American reference that adds belt-tension profile analysis and the minimum-sag tension criterion. The MechanixCalc conveyor calculator applies all three in sequence: ISO 5048 for power, DIN 22101 equal-roll cross-section geometry for capacity, and CEMA for the tension-profile sag check.
Does the calculator handle inclined and declined conveyors?
Yes. Enter a positive lift height H for an uphill conveyor — the incline resistance F_St = q_G·H·g is added to the effective pull. Enter a negative H for a regenerative (downhill) conveyor where F_St partially offsets the running resistance. The incline angle δ = arcsin(H/L) also feeds the cosine correction on the main resistance. Inclines steeper than 18° trigger a warning because most bulk materials require a cleated belt above that angle.
Is the ISO 5048 conveyor calculator free?
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