Cable Yarding How it works Rien Visser Virginia

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

Problem: Extraction of trees on steep terrain stems waterway

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Yarder on the landing

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

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

Three D’s of productive cable logging • ‘D’eflection • More deflection: – more payload – same cable tension • operator ‘D’eflection tailhold skyline • ‘D’eflection yarder choker-setter

Planning !!!!

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

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

Yarder Business Management – Daily production chart Target Average

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

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

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 $2500 - $7500

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