BisonConvey
ENGINEERING TOOLS

CONVEYOR BELT TENSION CALCULATOR

Calculate effective tension, motor power, and T1/T2

Estimate the effective tension Te a conveyor must overcome, the motor power required at the drive shaft, and the tight-side and slack-side tensions T1/T2 used to size belt strength. Based on the CEMA simplified formula combined with the Eytelwein capstan relation.

Units

Conveyor

Material

Drive

Result
Effective tension Te
8.92
kN
2005.2 lbf
Motor power P
17.84
kW
23.9 hp
Tight side T1
12.34
kN
2774.5 lbf
Slack side T2
3.42
kN
769.2 lbf
Formulas
  • Te = f · L · g · (2·Wb + Wm) · cos α + Wm · g · H
  • P = Te · v
  • T1 = Te · e^(μθ) / (e^(μθ) − 1)
  • T2 = Te / (e^(μθ) − 1)

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How the formula works

Effective tension Te is the net force the drive must apply at the head pulley to keep the belt moving steadily. It is the sum of the friction force from rolling over the idlers (proportional to length × total moving mass × idler friction factor) and the gravitational force lifting the material vertically (Wm·g·H).

Required motor power is simply Te times belt speed. Multiply by an extra 1.05–1.15 to cover drive efficiency losses (gearbox, coupling) when sizing the actual motor.

T1 and T2 come from the Eytelwein capstan equation T1 / T2 = e^(μθ). Combined with T1 − T2 = Te, this fixes both values. T1 is the design tension used for selecting belt carcass rating and splice length.

Idler friction factor reference

Pick f based on conveyor maintenance, dust load, and ambient temperature.

Conditionf
Clean, well-maintained, indoor0.018
Standard outdoor service0.020
Default for design0.022
Dusty, mining environment0.025
Heavy fouling / cold start0.030

Drive friction coefficient by lagging

Wrap factor μ varies with drum surface and belt cover condition.

Drive surfaceμ
Bare steel, dry0.30
Bare steel, wet0.20
Rubber lagged, dry0.35
Rubber lagged, wet0.30
Ceramic lagged, dry0.45
Ceramic lagged, wet0.40

Common pitfalls

  • Using the same f value for short and long conveyors — short conveyors (under 50 m) have larger relative end losses; consider a 1.05–1.10 multiplier on Te.
  • Forgetting that decline conveyors can have negative Te. The drive then becomes a brake, and you need a holdback or regenerative VFD instead of a plain motor.
  • Sizing the motor to exactly P. Real installations need a 15–25 % service margin for startup torque, accelerating loaded belts, and material build-up.
  • Confusing T1 with belt working tension. T1 is the maximum static tension in the belt loop; the actual belt selection adds a 6–10× safety factor over the carcass breaking strength.
  • Overlooking acceleration tension. Long, heavily loaded belts have a non-trivial Tac during start; use a soft-start drive or fluid coupling for L > 200 m or Q > 2000 t/h.

When you need a full design review

This calculator implements the CEMA simplified formula, which is accurate to about ±10 % for conventional troughed conveyors under steady operation. For long overland conveyors, complex profiles, low-temperature service, or any belt requiring DIN 22101 / ISO 5048 verification, dynamic start-up analysis, or formal load-case study, talk to a BisonConvey engineer.

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