Bearing Force Input Panel
Enter shaft geometry, applied loads, capacity data, and design factors. All force inputs use newtons.
Formula Used
R_BH = (F_H × a + M_H) / L
R_AH = F_H - R_BH
R_BV = (F_V × a + M_V) / L
R_AV = F_V - R_BV
F_r = √(R_H² + R_V²)
P = F_s × F_r when F_a / F_r ≤ e
P = F_s × max(F_r, X F_r + Y F_a) when F_a / F_r > e
P0 = max(F_r, X0 F_r + Y0 F_a)
L10 = (C / P)^p million revolutions.
Life hours = L10 × 1,000,000 / (60 × rpm)
Adjusted life = Life hours × a1 × lubrication factor
Static safety = C0 / P0
Use catalog factors for final machine design. This calculator supports preliminary engineering checks.
How To Use This Calculator
- Enter the distance between bearing centers.
- Enter the load position measured from bearing A.
- Add horizontal, vertical, and axial loads.
- Enter any applied couples from gears or pulleys.
- Set catalog capacity ratings and load factors.
- Choose the bearing family for life exponent selection.
- Press the submit button to view results above the form.
- Check the critical bearing, adjusted life, and static safety.
Example Data Table
| Input | Example value | Meaning |
|---|---|---|
| Bearing spacing | 600 mm | Distance from bearing A to bearing B. |
| Load position | 250 mm | Radial load location from bearing A. |
| Horizontal load | 1800 N | Side force from belt or gear action. |
| Vertical load | 2400 N | Weight or downward working force. |
| Axial load | 600 N | Thrust load along the shaft axis. |
| Dynamic capacity | 36 kN | Catalog rating for fatigue life checks. |
| Static capacity | 22 kN | Catalog rating for permanent deformation checks. |
Bearing Force Analysis Guide
Why Bearing Forces Matter
Bearings support rotating shafts and guide motion. Their loads come from gears, belts, couplings, impellers, wheels, and machine weight. A small error can create heat, noise, vibration, or short service life. Good force analysis separates radial load, axial load, and applied moments. It also shows which bearing receives the highest demand.
A shaft normally has two bearing supports. Each support reacts to the same external load differently. The load position controls the split. A force near bearing A usually raises bearing A reaction. A force beyond bearing B can reverse one reaction. That condition is common in overhung pulleys and cantilevered wheels.
Radial And Axial Loading
Radial force acts across the shaft. It can have horizontal and vertical parts. These parts are solved in separate planes. The resultant radial load is found by the square root method. Axial force acts along the shaft. It often comes from helical gears, thrust washers, fans, or preload.
Axial load may not divide equally. One bearing can locate the shaft. The other bearing can float. The calculator lets you set axial sharing. That option helps model common mechanical layouts. Use one hundred percent at bearing A when A is the locating bearing.
Equivalent Load And Life
Catalog life formulas use equivalent dynamic load. This value combines radial load, axial load, and service severity. The factors X, Y, and e come from bearing catalogs. They change with bearing type and geometry. Use catalog values when available. Default values are only planning estimates.
Bearing life is calculated in million revolutions. The exponent is three for ball bearings. It is ten thirds for roller bearings. Speed converts revolutions into hours. Reliability and lubrication factors reduce ideal life. High temperature can also reduce usable dynamic capacity.
Practical Design Notes
Static safety protects against permanent raceway damage. It matters during shock loads, slow starts, transport, and stalled machines. A low static safety factor is a warning. Increase bearing size, reduce overhung distance, improve alignment, or lower shock severity.
This tool is best for comparison and early design. Final selections need manufacturer data. Check fits, seals, lubricant, temperature, shaft stiffness, and housing accuracy. Also check misalignment and minimum load rules. Careful inputs make bearing choices more reliable and economical.
Input Quality
Start with a clean free body diagram. Mark every force with direction and distance. Keep units consistent before pressing submit. Use newtons for forces, millimeters for geometry, and kilonewtons for catalog capacities. Enter moments with a sign that matches the intended reaction direction. Compare several layouts instead of trusting one result. Moving a pulley closer to a bearing often lowers the worst reaction. Increasing bearing spacing can also help. Review both bearings because the lighter radial load may still carry more axial thrust. Save results and record assumptions for future maintenance decisions. Document catalog revisions so later design checks use the same rating assumptions safely.
Frequently Asked Questions
What does this bearing force calculator solve?
It solves support reactions, radial bearing loads, equivalent dynamic load, static equivalent load, estimated life, and safety factor. It is useful for shafts supported by two bearings.
Can I use it for overhung loads?
Yes. Enter a load position beyond the bearing span. The reaction at one bearing may become negative. That shows a reversed support direction.
What are X and Y factors?
X is the radial load factor. Y is the axial load factor. Bearing catalogs provide these values for each bearing type and load ratio.
What is the e limit?
The e limit checks whether axial force significantly changes equivalent load. If axial force is small, radial load may control the calculation.
How is bearing life estimated?
The calculator uses the standard rating life relationship. It compares dynamic capacity with equivalent dynamic load. Speed then converts revolutions into working hours.
Why does reliability reduce life?
Higher reliability means fewer failures are allowed. The adjusted life becomes lower because the design target is stricter than normal rating life.
Should I include preload?
Include preload when the bearing arrangement intentionally adds axial force. Preload increases equivalent load and can reduce expected life.
What does static safety mean?
Static safety compares static capacity with static equivalent load. It helps prevent permanent dents and deformation during heavy or slow loading.
Can this replace a manufacturer selection tool?
No. It supports early calculations and comparison work. Final bearing selection should use manufacturer catalogs and accepted engineering checks.
Why are there horizontal and vertical forces?
Many shafts carry loads in different directions. Solving each plane separately gives clearer reactions and a better resultant radial load.
What should I check after calculation?
Check life, static safety, alignment, lubrication, temperature, shaft deflection, and housing stiffness. Always verify critical designs using approved engineering design standards.