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Cable Yarding How it works…. Rien Visser, Virginia Tech.

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Presentation on theme: "Cable Yarding How it works…. Rien Visser, Virginia Tech."— Presentation transcript:

1 Cable Yarding How it works…. Rien Visser, Virginia Tech

2 Problem: Extraction of trees on steep terrain stems waterway

3 - suspend wire rope across the slope (skyline) stems skyline

4 Wire Rope (cable) Function: provides the elements of a rigging system to pull the stems from the forest to the landing Steel Core Strand Right hand ordinary lay 6 x 19

5 - Suspend cable from tailtree (or tailhold) and a yarder stems skyline tailhold yarder

6 Yarder Types Yarders Mobile Stationary Independent Steel tower/spar, wooden tower/spar, steel lattice work. Integral Swing Steel lattice work. Excavator type yarder. Integral Steel tube or steel lattice work. Either vertical or leaning.

7 Tower Function: Keeps the cable off the ground and provides lift to the stems, especially near the landing Independent or integrated Small (30ft), medium (60ft), large (90ft) Wooden spar, steel tower or lattice tower One-piece, folding or telescoping

8 Carrier Function: support yarder equipment and allows transportation Tracked, tires or skid Self-propelled, towed or carried/pulled Mounting for power-train

9 - add a carriage, mainline and drums stems skyline tailhold yarder mainline and carriage drums (winches)

10 Carriages Function: runs on the skyline to get the chokers out to the cut-over and the logs back to the landing simple single or double sheaves (blocks) slack-pulling capabilities –hand, mechanical or motorized

11 Winches (drums) / Brakes Function: transfers the power from the power-train to the cables to do the work Mechanical or hydraulic winches Water or air cooled brakes Drum stores the cable 1 – 5 working winches on a yarder

12 - add chokers, choker-setter and operator stems skyline tailhold yarder mainline and carriage choker -setter operator

13 Cab / Controls Function: to safely house the operator and control the operation of the yarder Houses the operator –protection from external environment –clear vision of operating area Controls the yarder –Old/simple: Mechanical levers –New/modern: Electronic switches and hydraulic levers

14 - complete system, ready to work….. stems skyline tailhold yarder mainline and carriage choker-setter operator

15 - how does it work….. stems skyline tailhold yarder choker-setter operator

16 - let carriage out….. stems skyline tailhold yarder choker-setter operator

17 - stop carriage above stems….. stems skyline tailhold yarder choker-setter operator

18 - choker-setter hooks up the stems….. skyline tailhold yarder choker-setter operator

19 - choker setter moves away….. skyline tailhold yarder choker-setter operator

20 - operator raises the stems….. skyline tailhold yarder choker-setter operator

21 - pulls towards landing….. skyline tailhold yarder choker-setter operator

22 - drop stems on landing…..and starts over again…. skyline tailhold yarder choker-setter operator

23 Yarder on the landing

24 Yarder on Roadside Limited stacking area Bell-logger or crane mounted on yarder Self-loading trucks on regular schedule

25 Effective yarder operation Its one thing to run one, another to operate it effectively….

26 Deflection Three Ds of productive cable logging More deflection: – more payload – same cable tension skyline tailhold yarder choker-setter operator

27 Planning !!!!

28 Landing Layout Cable layout –direction of pull –guyline location and anchoring Machinery layout –yarder location on the landing –other machinery on the landing –location of timber stacks –processing area –loading out area

29 Felling pattern Headpulls reduces productivity by 15% Fell trees at an angle to the skyline = 30 + slope (degree) –20 degree slope - fell at 50 degrees –40 degree slope – fell at 70 degrees Yarder SkylineFelling direction

30 Yarder Business Management – Daily production chart Target Average

31 Number of Chokers? More chokers means: greater ave drag volume more tangled strops increased risk of overloading Max Min

32 Direct and significant influence on: Human Performance ? System implementation and use Machine productivity Mechanical and operational delays Innovation

33 Learn-Curve Effect Takes a new employee about 3 months to get to 100% –Training helps – also increases potential –Basic cost of new employee estimated at $ $7500

34 Value of human performance? Yarder operator= $12 / hr Yarder costs= $110 / hr Timber Value = $1,000 / hr


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