KEVOS® MAKEOS · Mechanics
Crane Load Swing Check (Pendulum Period, Swing, Rope Tension)
If the trolley stops suddenly, how far will this hanging load swing, how long is each swing, and how much extra pull does the swing put on the rope?
Check of a load hanging from a crane trolley or hoist that stops abruptly from its travel speed: pendulum period for the rope length corrected for amplitude (as the pendulum period tool), the swing angle and horizontal swing from the kinetic energy of the load, the rope tension at the bottom of the swing including the centripetal force, the largest travel speed for your swing clearance, and checks against the clearance and the rated load.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Load mass | kg | Mass of the hanging load including the hook block below the sheave. |
| Rope length to the load centre of gravity | m | Length from the trolley sheave to the load’s centre of gravity. |
| Travel speed | m/s | Trolley or bridge travel speed when it stops. |
| Swing clearance available | m | Horizontal distance the load may swing before it hits something. |
| Rated load of the crane and rigging | kN | Rated load of the crane, hoist or rigging in force units. |
Method and formulas
- Period T = 2π √(L ÷ g), corrected by (1 + θ² ÷ 16) for amplitude (as the pendulum period tool).
- Rise of the load h = v² ÷ 2g; swing angle θ = cos⁻¹(1 − h ÷ L); horizontal swing = L sin θ.
- Rope tension at the bottom = m g + m v² ÷ L; largest speed for clearance c = √[2g L (1 − cos(sin⁻¹(c ÷ L)))].
- Example: stopping from 0.5 m/s swings the load 0.39089 m (3.7354°) every 4.916 s; keep travel below 0.63978 m/s for 0.5 m clearance.
Limitations
- Abrupt stop of the trolley; gradual braking reduces the swing.
- Point load on a single fall; long loads also rotate.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Set a travel speed limit near obstructions
- Explain load swing to crane operators
- Check the dynamic rope load from swinging
Who it is for
- Lifting supervisors
- Crane engineers
- Riggers
What you get
- Period and swing angle
- Horizontal swing and rope tension
- Largest travel speed for the clearance
Interpreting the result
- Swing grows with speed and with the square root of rope length: slow down and shorten the drop near obstructions.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 173–174. Topic reference; no source tables or recommended settings are reproduced.
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Open the Crane Load Swing Check (Pendulum Period, Swing, Rope Tension) calculator
