EFFECTIVE TENSION (TE) (Te)
Effective tension (Te) is the net tangential force that the drive pulley must transmit to the belt to overcome all motion resistances; it is the fundamental input for motor power and belt selection.
Effective tension, denoted Te, is the net belt force a conveyor's drive pulley must supply to keep the loaded belt moving at design speed. It equals the tight-side tension T1 minus the slack-side tension T2 at the drive: Te = T1 − T2. Te is the single most important number in conveyor design — it sets the required motor power, governs belt rating selection, and (combined with the wrap angle and lagging) determines whether the drive slips.
Te is built up by summing all motion resistances: the main resistance (rolling friction of belt on idlers, computed from the DIN 22101 friction factor f times the loaded mass per unit length), the slope resistance (belt and material weight times sine of incline), the secondary resistance (idler skirt friction, belt cleaner drag, accelerated material at the load chute), and any special resistances (curves, plough scrapers, trippers). DIN 22101 expresses this as Te = f × L × g × [qro + qru + (2qb + qg) cos δ] + H × g × qg + Σ FsT + Σ Fs.
Once Te is known, motor power is computed as P = Te × v / (η × 1000) kW, where v is belt speed in m/s and η is the drive-train efficiency. The motor is then sized to the next standard IEC frame, typically with a 10–15 % service factor. T1 and T2 individually are then split out using the Capstan / Eytelwein equation on the drive pulley wrap, which fixes the belt rating and the take-up force.
Formula
Te = T1 − T2 and P_drive = Te × v / (η × 1000)
| Symbol | Meaning | Unit |
|---|---|---|
| Te | Effective tension at the drive pulley | N |
| T1 | Tight-side belt tension entering the drive pulley | N |
| T2 | Slack-side belt tension leaving the drive pulley | N |
| v | Belt speed | m/s |
| η | Drive-train efficiency (motor + gearbox + coupling) | — |
| P_drive | Required motor shaft power | kW |
Reference standards
- DIN 22101Continuous conveyors — Belt conveyors for bulk materials
Defines the canonical Te build-up: main, slope, secondary and special resistances.
Related products
Related engineering tools
Related terms
- Capstan Equation (Eytelwein)
The Capstan or Eytelwein equation T1/T2 = e^(μθ) describes the maximum tension ratio a belt can sustain across a driven pulley before slipping, given the friction coefficient μ and the wrap angle θ in radians.
- Drive Pulley
The drive pulley is the powered drum of a conveyor that transmits torque from the gearbox to the belt by friction, generating the effective belt tension Te that overcomes all resistances.
- Friction Factor (f)(f)
The friction factor f is the dimensionless DIN 22101 coefficient (typical range 0.018–0.030) that lumps all idler bearing, belt indentation and seal friction into a single number for main-resistance calculation.
- DIN 22101
DIN 22101 is the German standard 'Continuous conveyors — Belt conveyors for bulk materials — Basis for calculation and design', the de facto international reference for belt conveyor engineering.
- Belt Sag
Belt sag is the vertical drop of a conveyor belt between two adjacent idlers under the combined weight of belt and load, typically kept below 1.5 % of idler spacing on the carry side.