Working Formulas for Belting Applications
When selecting a conveyor belt for a specific application, it is important to consider a variety of factors, such as the type of material being conveyed, the weight of the material, the speed of the conveyor, and the desired incline or decline angle. These calculations can help determine the appropriate belt width, thickness, and tension needed to ensure optimal performance and longevity of the belt. Additionally, other factors such as the environment in which the belt will be operating, such as temperature and humidity, should also be taken into consideration. By using these calculations, you can custom-choose the belt product that best fits your needs and ensures the safe and efficient movement of your materials.
Code of Symbols
| B | Sine of Angle of Incline | G2 | Load per Hour (in lbs.) | C | Center to Center distance (in Inches) |
| HP | Horsepower | D | Diameter or Drive Pulley (in inches) | K | Drive Factor (See Table #2 Below)) |
| d | Diameter of Tail Pulley (in inches) | L | Belt Length (in inches) | E | Effective Tension (in lbs.) |
| M | Belt Weight (See weight in lbs. PIW for particular belt specification)(overall length, not center to center) | E1 | Slack Side Tension (in lbs.) | P | Product Weight (in lbs.) |
| E2 | Tight Side Tension (in lbs.) | RPM | Revolutions per Minute | F | Coefficient of Friction (See Table #1 Below) |
| S | Speed (Feet Per Minute) | G1 | Load Per Sq. or Cu. Ft. (in lbs.) | T | Operating Tension PIW (in lbs.) |
| W | Belt Width (in inches) | ||||
Table #1Coefficient of Friction “F” (Belt to Slider Bed or Rollers) |
||
| Belt | Steel or Aluminum | Metal Rollers |
|---|---|---|
| FS pulley side | .30 to .35 | .10 to .15 |
| Bare Duck or BB side | .20 to .25 | .10 to .15 |
| Cover on pulley side | .50 to .55 | .10 to .15 |
| Note: The highest figure is the most conservative | ||
Table #2Drive Factor “K” |
||||
| Belt Wrap on Drive Pulley | Screw Take-Up | Gravity or Weighted Take-Up | ||
|---|---|---|---|---|
| Bare | Lagged | Bare | Lagged | |
| 180° | 1.6 | 1.0 | .84 | .50 |
| 220° | 1.2 | .6 | .62 | .35 |
| 240° | 1.0 | .5 | .54 | .30 |
| Note: The drive factor has a definite effect on tension | ||||
Belt Length
For when pulleys are approximately the same size:
| L = | D + d | x 3.1416 | + 2C |
| 2 |
For when one pulley is much larger than the other (at least 3 or more times larger):
| L = | D + d | x 3.1416 | + 2C + | (D – d)2 |
| 2 | 4C |
Belt Speed
Belt speed formula in Feet Per Minute.
S = D x RPM x .2618 x 1.021
Load on Belt
At one time when load is known (per square foot or per cubic foot basis):
P = G1 x C (in ft.) x W (in ft.)
At one time when load is known (by lbs. per hour or tons per hour):
| P = | G2 | x C (in ft.) |
| S x 60 (minutes) |
Belt Weight
L (in ft.) x (Belt Weight PIW x W)
Horsepower
To drive horizontal belt conveyors:
| HP = | F x S x (P + M) |
| 33,000 |
To drive inclined belt conveyors:
| HP = | (P x B) + (P + M) x F x S |
| 33,000 |
Effective Tension
E = F x (P +M)
Slack Side Tension
Additional tension required to prevent slippage on drive pulley:
E1 = E x K
Tight Side Tension
Total tension required to move belt and load
E2 = E + E1
Operating Tension
Determines working strength of belt to handle job on per inch of width basis:
| T = | E2 |
| W |
Effective Tension
Length of Belt in Roll
Approximate only
| L = | D2 – 100 |
| 15.3T |
| D | Diameter in inches |
| T | Thickness in inches |
| L | Length in Feet |
| (approximate) |