TOOLS · GLOSSARY
Drive & Power — Belt Conveyor Glossary
37 terms on Drive & Power, 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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37 terms
Drive power
Motor power needed to move the material against gravity and friction.
Gearbox
Speed reducer between motor and drive pulley, sized for torque and duty.
Fluid coupling
Hydraulic coupling that smooths start-up and shares load between motors.
Backstop
Device that prevents an inclined conveyor from running backwards when stopped.
Brake
Device that stops or holds the conveyor; needed on downhill or high-inertia drives.
Wrap angle
Angle over which the belt contacts the drive pulley; a larger wrap means more grip.
Soft starter / VFD
Electronic control that limits starting torque and current and allows speed control.
Drive efficiency
Combined efficiency of motor, coupling, gearbox and pulley (≈ 0.85–0.95).
Motor
Prime mover of the conveyor; sized from the calculated drive power plus a service factor.
Helical gearbox
Parallel-shaft reducer; common for medium-power conveyor drives.
Bevel-helical gearbox
Right-angle reducer used where the motor must sit alongside the pulley.
Planetary gearbox
Compact high-ratio reducer for drum motors and tight installations.
Gear ratio
Motor speed divided by pulley speed; sets the belt speed for a given pulley diameter.
Shaft-mounted reducer
Reducer hung on the pulley shaft and held by a torque arm.
Torque arm
Link that reacts the reducer torque back to the structure.
Flexible coupling
Coupling that absorbs misalignment between motor and gearbox.
Gear coupling
Toothed coupling for high torque and slight misalignment.
Fluid coupling (hydro)
Hydraulic coupling that limits starting torque and balances multiple motors.
VFD (variable frequency drive)
Electronic drive that controls belt speed and gives a soft, controlled start.
Soft starter
Device that ramps motor torque and current at start-up.
Motor service factor
Allowed short-term overload above rated motor power.
Cage induction motor
Standard AC motor for conveyor drives; robust and low maintenance.
Explosion-proof motor
Motor certified for gassy or dusty hazardous areas, e.g. underground coal.
Backstop (holdback)
One-way device that stops an inclined conveyor from running back.
Disc brake
Brake that stops or holds a downhill or high-inertia conveyor.
Run-up (over-speed) switch
Sensor that trips the conveyor if the belt runs faster than the drive.
Zero-speed switch
Sensor that detects a stalled or slipping belt.
Motor power rating
Installed motor power, chosen from the calculated drive power plus service factor.
Drive pulley power
Power delivered at the pulley before efficiency losses.
Starting torque
Torque needed to break away and accelerate the loaded belt; often 1.5–2× running torque.
Belt slip ratio
Difference between belt speed and pulley rim speed, divided by belt speed.
Shaft-mounted gearbox
Gearbox that mounts directly onto the pulley shaft and reacts against a torque arm — no foundation or coupling needed.
Pin-bush coupling
Flexible coupling with rubber bushes on pins; absorbs shock and small misalignment. The workhorse on conveyor drives.
Gearbox service factor
Ratio of gearbox rated capacity to actual duty. Belt conveyors start fully loaded, so 1.5 or more is normal.
Gearbox ratio
Input speed divided by output speed. It sets belt speed together with pulley diameter.
Roller backstop
One-way clutch that lets the conveyor run forward and blocks reverse rotation on inclined conveyors.
Sprag backstop
Backstop with shaped sprags engaging almost instantly, with very little reverse rotation before lock-up.
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