Mechanical Technical Information

Torque, Horsepower and other Calculations:

HP & Torque

Horsepower = (Torque Ft*lbs)(RPM)
5252

Torque Ft*lbs = (5252)(Horsepower)
…………………………RPM

At 1800 RPM a motor develops 3 ft-lb per HP
At 1200 RPM a motor develops 4.5 ft-lb per HP

Conveyor Speed

Feet Per Minute = (0.262)(Head Pulley Dia in Inches)(RPM)

RPM = Feet Per Minute
……….. (0.262)(Head Pulley Dia in Inches)

Dia in Inches = Feet Per Minute
…………………………. (0.262)(RPM)

Sheaves

Do Not use Grey Cast Iron Sheaves with a Rim Speed in Excess of 6,500 Feet Per Minute

Grid Example

Sheave RPM	Max Diameter
1200 RPM	20.7″ Max
1750 RPM	14.2″ Max
3600 RPM	6.9″ Max

Maximum Cast Iron Sheave Diameter at RPMs

Belt Length Information

If you do not already have a “Tentative Center Distance”, a good estimate is to use either the Larger sheave diameter “D” or 1/2(D + 3d), whichever is Larger. You can then find a tentative belt length by solving the following formula.

“Tentative Belt Length” = 1.57(D + d) + (“Tentative Center Distance” x 2)

Where:
……… D = Diameter of large sheave
……… d = diameter of small sheave

“Belt Length” = 2C + 1.57(D + d) + [(D – d)² / 4C]

Where:
……… C = Actual Center Distance

Heat Required to Make the Interference Bore Fits

▲D = D x ▲t x Le
Change in Distance in inches = ▲D
Distance across the bore in inches = D
Change in Temperature in Fahrenheit= ▲t
Linear Coefficient of Expansion = Le
Le for steel = 0.000 0063 in/in/°F
Le for steel = 0.063 in growth / 10,000 °F in

Example:
D of a 6320 Bearing is 100 mm = 3.9362 inches
If heating a bearing from 70°F to 250°F
▲D = (3.9362) x (250°F – 70°F) x 0.000 0063
▲D = (3.9362) x (250°F – 70°F) x (0.063 / 10,000)
▲D = 0.0044″

Bushings

Tapered Bushings

QD Bushings

Split Tapered Bushings

Scaling Laws
[W’/(rN³D⁵)]₂ = [W’/(rN³D⁵)]₁

W = Power
r = fluid density
N = rotational speed
D = impeller diameter