# Working Formulas

### Code of Symbols Click to view the code of symbols used in formulas below

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) |

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) |

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) |

### Belt Length

when pulleys are approximately the same size

L = | D + d | x 3.1416 | + 2C |

2 |

### Belt Length

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

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.)

### Load on Belt

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 |

### Horsepower

to drive __inclined__ belt conveyors

HP = | (P x B) + (P + M) x F x S |

33,000 |

### Effective Tension

pull needed to move belt and load __horizontally__

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 |

### Length of Belt in a Roll

__approximate only__

L = | D^{2} - 100 |

15.3T |

D | Diameter in inches |

T | Thickness in inches |

L | Length in Feet (approximate) |

## Table #1Coefficient of Friction "F" |
||

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 |