Belt Conveyor Capacity & Drive Horsepower Calculator (CEMA)
Calculate bulk material handling capacity in Tons Per Hour (TPH), volumetric throughput (ft³/hr), belt speed (FPM), effective drive tension (T_e), and electric motor horsepower according to CEMA standards.
Conveyor Geometry & Material
Capacity & Motor Spec
CEMA Troughed Idler Cross-Section & Material Surcharge
Vector cross-section illustrating 3-roll idler troughing angle, material surcharge angle ($20^circ$), and side elevation profile with head/tail pulleys.
Bulk Material Mechanics: CEMA Capacity & Drive Tension Equations
Conveyor capacity is governed by cross-sectional material load area on troughed idlers and linear belt velocity. Drive horsepower must overcome empty friction, material horizontal translation, and gravitational lift.
\text{TPH} = \frac{A_{\text{cross}} \times V_{\text{speed}} \times \rho_{\text{bulk}} \times 60}{2000}
2. Material Gravitational Lift Horsepower:
HP_{\text{lift}} = \frac{\text{TPH} \times H_{\text{lift}}}{990} \quad \Big(1\text{ HP} = 33,000\text{ ft-lb/min}\Big)
3. Effective Drive Tension (T_e):
T_e = \frac{HP_{\text{motor}} \times 33,000 \times \eta_{\text{drive}}}{V_{\text{speed}}}
4. Euler-Eytelwein Drive Pulley Slip Condition:
\frac{T_1}{T_2} \le e^{\mu \theta} \quad (\mu = 0.35 \text{ for rubber lagged pulley; } \theta = 210^\circ \text{ wrap})
1. Drive Pulley Slip Belt Fire Catastrophe
When slack-side tension ($T_2$) drops due to insufficient counterweight take-up, the drive pulley spins against a stalled belt ($T_1/T_2 > e^{\mu\theta}$). Friction generates $800^\circ\text{F}$ within 90 seconds, melting the rubber carcass and igniting massive coal/grain conveyor gallery fires.
2. Exceeding Maximum Incline Slope Rollback
Every bulk material has a maximum safe incline angle (e.g. wet gravel $15^\circ$, dry sand $18^\circ$). Exceeding this angle causes round stones to roll backward down the belt like bowling balls, destroying loading skirtboards and showering workers.
3. 45-Degree Idler Junction Fatigue Slit
Deep $45^\circ$ troughing idlers maximize tonnage but bend the rubber belt sharply over the gap between center and wing rollers. Heavy steel-cable or fabric belts not rated for $45^\circ$ troughing will fatigue and split longitudinally down the idler junction lines.
4. Lump Size vs Belt Width Blockage
CEMA mandates that belt width must be at least 3 times the maximum uniform lump size (or 2.5 times the maximum irregular lump size). Loading 10" boulders onto a 24" belt jams transfer chutes, slices belt covers, and causes instantaneous material spillage.
5. Underestimating Starting Torque & Sag
Starting a fully loaded conveyor requires 200% to 250% of running motor torque to overcome static inertia and sag between idlers. Sizing the motor purely for steady-state run horsepower causes the motor to stall on loaded restart, tripping circuit breakers.