Enter Cantilever Details
Use forces in kilonewtons and distances from the selected tipping line in metres.
Formula Used
The calculator uses moment balance around a selected tipping line. Moments use force multiplied by perpendicular distance.
Counterweight output is shown as force. The estimated mass converts kilonewtons using standard gravity. Use verified load paths, actual centres of gravity, manufacturer limits, and applicable project requirements before construction.
How to Use This Calculator
- Select the tipping line that represents the possible rotation edge.
- Enter the primary supported load and its horizontal arm.
- Add the dead load of the boom, platform, or attachment.
- Enter installed ballast and its centre distance behind the tipping line.
- Include only verified support resistance from approved anchors or foundations.
- Choose the project-approved safety factor, then calculate the required balance.
- Review the output with a qualified engineer before selecting ballast blocks.
Example Calculation
| Input or result | Example value | Purpose |
|---|---|---|
| Supported load | 20.00 kN at 2.50 m | Creates 50.00 kN·m overturning moment. |
| Equipment dead load | 4.00 kN at 1.40 m | Adds 5.60 kN·m overturning moment. |
| Safety factor | 1.50 | Sets a 83.40 kN·m target resisting moment. |
| Counterweight arm | 1.80 m | Converts required resistance into counterweight force. |
Counterbalance Planning for Cantilever Loads
Cantilever work creates rotation around a possible tipping edge. The load creates an overturning moment. A counterweight creates a resisting moment. The two moments must be compared using the same reference line.
Start With the Tipping Line
The tipping line is usually the outer support edge. It can also be an anchor group edge. Select it before measuring any arms. A wrong reference line changes every result.
Measure Horizontal Arms Carefully
Moment depends on perpendicular horizontal distance. Measure each force to its centre of gravity. A small distance error can change ballast needs. Long outreach increases risk quickly.
Include More Than the Main Load
The carried object is not the only force. Platforms, booms, brackets, and tools add moment. Include their dead loads where known. Use conservative values when details remain uncertain.
Use Verified Support Resistance
Foundations and anchors may resist part of the overturning demand. Enter this value only when it is documented. Do not assume soil or framing capacity. Hidden movement can reduce real resistance.
Apply the Correct Safety Factor
The safety factor increases the target resisting moment. It helps address uncertainty and design requirements. The correct factor depends on equipment and regulations. Project documents should control the selected value.
Read the Result as a Planning Check
The result shows the counterweight needed at the entered arm. Moving ballast farther from the tipping line reduces required force. Moving it closer increases required force. Actual ballast must still satisfy placement and connection limits.
Check the Full Load Path
A balanced moment does not prove a safe structure. Check member bending, shear, connection capacity, anchorage, and foundation pressure. Consider wind, impact, dynamic lifting, and accidental eccentricity. Qualified review remains essential before site use.
Account for Dynamic Actions
Static weights may not describe actual work. Hoisting, braking, and vibration can amplify forces. Moving equipment shifts its centre of gravity. Evaluate these conditions carefully through approved design methods.
Document the Arrangement
Record tipping lines, dimensions, load cases, ballast, and support assumptions. Mark locations. Prevent removal. Recheck after changes in outreach, attachments, lifted load, or site conditions.
Use a Controlled Load Case
Check the worst credible configuration, not only normal operation. Include maximum outreach, the heaviest load, and the least favorable ballast position. A documented load case improves repeatable site decisions for crews.
Frequently Asked Questions
1. What is counterbalance in a cantilever system?
Counterbalance is a resisting load placed opposite the cantilevered load. Its force and distance create a resisting moment. The arrangement helps prevent rotation around a support edge or other selected tipping line.
2. Why does the calculator use kN and metres?
Kilonewtons and metres produce moments in kN·m. This is common in structural work. Any consistent force and distance system can work, but mixed units cause incorrect moment results.
3. Is counterweight force the same as ballast mass?
No. Counterweight is a force, while ballast mass is measured in kilograms or tonnes. The calculator estimates mass from force using standard gravity. Actual supplied ballast may have different verified weights.
4. What should I use for the safety factor?
Use the factor required by the responsible engineer, equipment manufacturer, contract documents, and applicable rules. Do not choose a factor casually. Different activities and systems can require different design approaches.
5. Can I include anchor resistance?
Yes, but only use a verified resisting moment from approved anchors, foundations, or structural supports. Do not enter assumed resistance. The full anchor load path still requires separate design checks.
6. Why is the counterweight arm important?
The arm multiplies the counterweight force. A longer arm creates more resisting moment for the same ballast. Space limits, member strength, and connection details may restrict the usable arm.
7. Does this check beam strength?
No. This tool checks a simplified moment balance only. It does not check beam bending, shear, deflection, local buckling, welds, bolts, anchors, soil pressure, or fatigue.
8. Should wind load be included?
Include wind-induced forces and moments when they are relevant to the work condition. Wind can be critical for suspended loads, panels, platforms, and exposed structures. Use project-specific loading guidance.
9. What is the selected tipping line?
It is the edge or axis about which the system could rotate. It may be a support edge, wheel line, base edge, or anchor group boundary. Select the actual controlling line.
10. Can I reduce ballast by moving it farther back?
Usually, yes. A greater counterweight arm reduces the force needed for the same resisting moment. However, the extended support must safely carry that ballast and remain within approved geometry limits.
11. Is this suitable for final construction approval?
No. Use it for early planning and sensitivity checks. Final construction approval should come from qualified professionals using verified loads, system details, design standards, and site-specific conditions.