Mechanical Technical Information

Mechanical Technical Information

 Torque, Horsepower and other Calculations:

HP & Torque

Horsepower = (Torque Ft*lbs)(RPM)

Torque Ft*lbs = (5252)(Horsepower)

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)


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)

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

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

……… 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

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″


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


Timken Bearing Search Tool 

  • Identifies all of the cups related to a cone and all of the cones related to a cup.
  • Also searches from dimension ranges

SKF Bearing Handbook for Electric Motors

  • Speed Ratings and
  • Shaft & Housing Diameters
  • Grease Relube Recommendations

EDT Selection

  • Plane Bearing design checklist


Belt Drive Data Collection Worksheet

Helpful Videos:

How do SKF Shaker Bearings Work

How to install an Input Coupling on Rexnord Planetgear

SKF Bearing Installation Video


Posi Lock Pullers

How a Ball Bearing is Made

Simatec lubrication

SKF Marathon Food Line bearing