Felling Moment Calculator
Digital version of Säker Skog's felling-moment chart · model after Gullberg (2006), generalised with Chave (2014) for species outside the Nordics
The tree
35 cm
23.0 m
1.0 m
0 m/s
The cut
20 %
3.2 cm
Species parameters
| Basic density | 0.40 t/m³ |
| Moisture factor | ×2.05 |
| Green density | 0.82 t/m³ |
| Centre of gravity | 40 % of length |
| Stump diameter/DBH | ×1.34 |
| Wind area | 0.20·DBH m² |
| Mass function | Marklund/Gullberg |
Set by the species selection. Outside the Nordics, centre of gravity and stem taper are the largest uncertainties in the model.
Required felling moment
851 daNm (kgm)
Diagram
selected leansufficient with margintight
Tools
| Tool | Max moment | Margin | |
|---|---|---|---|
| Pole 5 m length | 417 | -51 % | |
| Felling lever, stand + push | 420 | -51 % | |
| Breaking bar, medium | 600 | -30 % | |
| Small wedge | 866 | +2 % | |
| Breaking bar, large | 962 | +13 % | |
| Large wedge | 1,170 | +37 % | |
| Winch 0.5 t, anchor 2.5 m | 1,240 | +46 % | |
| Ox-break 4 m pole | 1,247 | +47 % | |
| Felling director (Stalpen) | 1,588 | +87 % | |
| Large wedge, max | 1,670 | +96 % | |
| 2 large wedges | 1,993 | +134 % | |
| Winch 0.5 t, anchor 5 m | 2,485 | +192 % |
M = m·g·(cog·lean + (Ds/2 − notch − hinge/2)) + hinge bending resistance ± wind. Mass from Marklund/Gullberg for spruce, pine and birch, otherwise Chave et al. (2014) with the species density. The tool forces are human muscle power and apply everywhere.
These are theoretical calculations. The user is solely responsible for all decisions on how a tree felling is carried out.
These are theoretical calculations. The user is solely responsible for all decisions on how a tree felling is carried out.