TOOLS · GLOSSARY
Parameters & Dimensions — Belt Conveyor Glossary
125 terms on Parameters & Dimensions, each with its working definition, the governing symbol or formula where one exists, and a link to the standard behind it.
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125 terms
Belt width (nominal)
Standard belt width; the primary sizing dimension (500–2400 mm).
Belt width (effective)
Usable load width after CEMA edge clearance: b = 0.9·B − 0.05 m.
Troughing angle λ
Angle of the outer carrying idler rolls; 20°/35°/45° standard.
Surcharge angle β
Angle of the load pile on top of the trough; less than the repose angle.
Angle of repose
Steepest angle a free pile of material will hold.
Material lump size
Maximum lump dimension; limits belt width and chute design.
Lump size ratio
Ratio of belt width to maximum lump; usually above 3 for sorted, 2 for run-of-mine.
Bulk density ρ
Mass of loose material per unit volume; scales capacity and power.
Belt speed v
Linear speed of the belt; 1.5–5 m/s typical.
Capacity Q
Mass throughput of bulk material; rises with width, speed and trough angle.
Volumetric capacity Qv
Volume throughput = cross-section area × belt speed × 3600.
Cross-section area A
Trough area plus surcharge area of the material on the belt.
Lift height H
Vertical rise of the material; drives the largest power component.
Conveyor length L
Centre-to-centre length of the conveyor; sets the friction power term.
Inclination angle δ
Angle of the conveyor to the horizontal; limits material stability.
Max inclination
Steepest safe incline before material rolls back — coal ~18°, ore ~20°, grain ~15°.
Belt tension T
Running force in the belt; sets belt class, take-up and shaft loads.
Effective tension Te
Tension that drives the belt: Te = 1000·P/v.
Slack-side tension T2
Minimum tension needed to prevent slip, set by the drive factor.
Drive factor
Ratio e^μα/(e^μα−1) linking slack-side to effective tension.
Drive power P
Motor power to move material against gravity and friction, divided by efficiency.
Friction coefficient f
Specific main-resistance factor, about 0.02–0.04.
Belt sag f
Mid-span dip between idlers; kept below 1–2 % of spacing.
Idler spacing a
Distance between carrying or return idler sets.
Idler load F
Force on one idler set = (qₘ + belt mass)·spacing·g.
Idler rotational resistance
Torque to turn an unloaded roll; low drag saves power.
Idler runout (TIR)
Total indicated runout of the roll; affects noise and belt life.
Roll diameter D
Tube outside diameter; 89/108/133/159 mm typical.
Roll wall thickness
Tube wall thickness; sets wear life under abrasive material.
Pulley diameter D
Pulley outside diameter; sets the belt bending stress.
Belt-wrap angle α
Arc of belt contact on the drive pulley; more wrap means more grip.
Friction coefficient belt–pulley μ
Friction between belt and pulley; ~0.25 dry, 0.35 lagged, lower if wet.
Minimum curve radius
Smallest vertical or horizontal radius allowed for the belt path.
Fill factor
Ratio of actual loaded area to the geometric trough area; 0.7–0.95.
Service factor SF
Multiplier covering start, surges and duty severity.
Design life
Target service hours before major overhaul.
Availability
Fraction of time the conveyor is able to run.
Utilisation
Fraction of capacity actually used in normal operation.
Belt load per metre
Material mass per running metre, qₘ = Q/(3.6·v).
Idler load rating
Rated static and dynamic load an idler set can carry.
Bearing dynamic load C
Load a bearing can carry for a rated life (usually 1 million revolutions).
Bearing life L10h
Hours at which 10 % of bearings are expected to fail.
Idler speed limit
Maximum rpm before seal and bearing life falls sharply.
Belt weight
Mass of the belt per unit length; enters power and idler load.
Cover wear rate
Loss of cover thickness per unit of tonnage; sets belt life.
Abrasion resistance index
Relative resistance of the rubber, measured by ISO 4649.
Cover tensile strength
Tensile strength of the cover rubber; higher means better wear life.
Hardness (Shore A)
Rubber hardness; affects wear, grip and flexibility.
Elongation at break
Strain the cover rubber reaches before tearing.
Tear strength
Resistance of the rubber to a growing cut.
Working temperature range
Temperature band the belt and components can tolerate.
Ambient temperature
Site air temperature; drives rubber grade selection.
Material temperature
Bulk material temperature, decisive for heat-resistant belts.
Altitude derating
Reduction in motor and gearbox rating at high altitude.
Material moisture content
Water content of the bulk material; drives stickiness and capacity loss.
Edge distance (CEMA)
Standard clearance from the belt edge to the material: 0.05·B + 25 mm.
Idler trough depth
Vertical depth of the troughing profile; rises with trough angle.
Belt troughability index
Measure (ISO 703) of how well the belt folds into the trough.
Belt mistracking limit
Offset at which a deviation switch should trip — often 5 % of belt width.
Belt overlap
Amount the belt extends beyond the pulley face each side.
Spillage rate
Mass of material lost per hour at transfer and along the run.
Carry-back rate
Mass of material returning on the belt per unit time.
Dust emission rate
Dust released at a transfer point; target usually below 10 mg/m³.
Noise limit
Maximum permitted sound level, typically 85 dB(A) at 1 m.
Vibration velocity
Measure of machine vibration used for condition monitoring.
Bearing temperature alarm
Temperature at which an alarm or trip is set — often 70–80 °C.
Gearbox oil temperature
Recommended oil temperature band for a conveyor gearbox.
Motor temperature rise
Temperature rise above ambient at rated load; class B/F insulation.
Power factor
Ratio of real to apparent power of the drive motor.
Starting current ratio
Starting current as a multiple of full-load current; reduced by soft start.
Duty cycle
Continuous, intermittent or cyclic duty of the conveyor.
Conveyor belt width series
Standard widths: 500, 650, 800, 1000, 1200, 1400, 1600, 1800, 2000, 2200, 2400 mm.
Idler diameter series
Standard roll diameters 63.5, 76, 89, 108, 133, 159, 194 mm.
Pulley diameter series
Standard pulley diameters 250, 320, 400, 500, 630, 800, 1000, 1250, 1400 mm.
Belt ply/strength series
Common classes EP 100–EP 500 and ST 630–ST 5400 (N/mm).
Gearbox ratio series
Nominal ratios (e.g. 20, 25, 31.5, 40) used to reach target belt speed.
Motor power series
Standard motor sizes 7.5, 11, 15, 22, 30, 45, 55, 75, 90, 110, 132, 160, 200 kW.
Tolerance (dimensional)
Allowed deviation from the nominal dimension.
Surface roughness Ra
Arithmetic mean roughness of a machined surface.
Straightness tolerance
Allowed deviation of a member from a straight line.
Concentricity tolerance
Allowed offset between axes of rotation.
Balance grade (G)
Residual unbalance class of a rotating part, e.g. G6.3.
Belt width 400 mm
Smallest standard fabric-belt width for light duties and short transfers.
Belt width 500 mm
Light-duty standard belt width.
Belt width 650 mm
Common width for small coal and aggregate lines.
Belt width 800 mm
Sit alongside 1000 mm as the workhorse industrial width.
Belt width 1000 mm
The most widely specified belt width in mining, cement and ports.
Belt width 1200 mm
High-capacity trunk conveyor width.
Belt width 1400 mm
Heavy trunk and overland conveyor width.
Belt width 1600 mm
Very high tonnage lines and port shiploaders.
Belt width 1800 mm
Large overland and bulk terminal conveyors.
Belt width 2000 mm
Maximum common width for single-flight conveyors.
Belt width 2200 mm
Special large width for very high tonnage installs.
Belt width 2400 mm
Largest routine width for bulk terminals and mine trunk lines.
Idler roll Ø89 mm
Smallest standard conveyor roll diameter; light duties and narrow belts.
Idler roll Ø108 mm
Most common idler diameter worldwide for medium belts and duties.
Idler roll Ø133 mm
Standard heavy-duty carrying and return roll diameter.
Idler roll Ø159 mm
Heavy duty roll for high tonnage, impact zones and wide belts.
Idler roll Ø194 mm
Largest common roll diameter; long-life service on trunk conveyors.
Pulley diameter 250 mm
Tail or snub pulley diameter for small lines.
Pulley diameter 315 mm
Small drive or tail pulley diameter.
Pulley diameter 400 mm
Common tail pulley diameter for 800–1000 mm belts.
Pulley diameter 500 mm
Standard drive pulley diameter for medium tension belts.
Pulley diameter 630 mm
Typical drive pulley diameter for EP belts at moderate tension.
Pulley diameter 800 mm
Standard drive pulley diameter for steel-cord and heavy EP belts.
Pulley diameter 1000 mm
Heavy drive pulley for high-tension steel-cord belts.
Pulley diameter 1250 mm
Large drive pulley; reduces belt bending stress on thick steel-cord belts.
Pulley diameter 1400 mm
Largest routine drive pulley diameter for overland trunk conveyors.
Trough angle 20°
Shallow trough for very wide belts and free-flowing material.
Trough angle 25°
Light trough angle for wide belts and unit loads.
Trough angle 30°
Common trough angle for coal and aggregate lines.
Trough angle 35°
Global default trough angle; best balance of capacity and belt life.
Trough angle 40°
Deep trough for higher capacity per belt width.
Trough angle 45°
Deepest standard trough; maximum capacity but higher belt wear.
Idler spacing 1.0 m
Close spacing for high tonnage or heavy material.
Idler spacing 1.2 m
Standard carrying idler spacing for most bulk duties.
Idler spacing 1.5 m
Wide spacing for light material and low tonnage.
Idler spacing 3.0 m
Typical return idler spacing; roughly 2.5–3.5 m on the return strand.
Belt speed 1.0 m/s
Slow speed for dusty, light or fragile material.
Belt speed 1.6 m/s
Common low speed on cement and fertiliser lines.
Belt speed 2.5 m/s
Workhorse speed for general bulk handling.
Belt speed 3.15 m/s
Higher speed for coal and aggregate trunk lines.
Belt speed 4.0 m/s
High speed on long overland and port conveyors.
Belt speed 5.0 m/s
Very high speed; needs premium idlers and careful loading.
Belt speed 6.0 m/s
Upper practical range; used in high-capacity shiploading.
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