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FRST 261 - Forest Harvesting Systems > Cable logging > Flashcards

Cable logging Flashcards

1
Q

What are the 4 different ways logs can be towed by cable?

A
  • Blind lead - logs not visible from tower top
  • Ground lead - no lift on front of log
  • Partial suspension - front of log is lifted clear
  • Full suspension - entire log suspended
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2
Q

Define Deflection

A

The amount the cable sags by

6% is an approximate goal in field situation

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3
Q

Define Lift

A

upward force on end of log

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4
Q

What is the relationship between line tension and carrying capacity?

A

Inverse, the more tight the line is, the less lifting capacity.

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5
Q

What 3 things influence deflection and lift?

A
  1. Shape of terrain
  2. Position of the landing (road location)
  3. Position of the tail holds (boundary location)
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6
Q

What is the ideal slope shape for cable yarding?

A

Concave

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7
Q

How might you handle a convex slope?

A

Establish a backspar to add height to the tailhold.

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8
Q

What is the relation ship between tension and deflection?

A

Inverse, The less tension, the greater the deflection.

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9
Q

How does deflection affect turn size?

A

The less deflection, the higher the turn size

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10
Q

How can forest engineers control deflection?

A

Locating suitable roads and felling boundaries

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11
Q

How can lift be temporarily increased to get the log over an obstacle?

A

Operator uses the break on the haul back line to generate additional tension which will generate more lift on the front end of the log.

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12
Q

What are some characteristics of High lead

A
  • Need a 2 drum yarder. One for mainline one for haulback
  • Tailblock and corner block at back end.
  • Third drum for strawline
  • Butt rigging for choker hookup
  • Guylines to support the tower
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13
Q

What are the 5 steps of a cable yarding “Turn” in highlead

A
  1. Chokerman chokes logs
  2. Rigging slinger whistles to signal yarding engineer to move the lines
  3. Mainline pulls butt rigging and logs to yarder
  4. Chaser unhooks logs
  5. Haulback pulls butt rigging back into block
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14
Q

What are the respective pulleys called for the mainline and haulback?

A

Bull block: mainline

Fair lead: haulback

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15
Q

What is the tower referred to in a highlead system?

A

the spar.

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16
Q

What are the specs of highlead systems?

A
  • 15-36m height
  • drums can carry up to 300m of mainline
  • 600m of haulback
17
Q

What is the standard crew for Highlead

A
  • Full crew is minumum of 5 men
  • 1 hooktender (in charge)
  • 1 yarder engineer (runs machine)
  • 1 chaser (unhooks choker)
  • 1-3 choker setters (hooks up chokers)
  • 1 rigging slinger ( assist chokers and control rigger signal )
18
Q

Is Highlead better for uphill or downhill yarding?

A
  • Most effective on uphill yarding

- when yarding downhill or cross hill, logs can easily get hung up on the wrong side of stumps.

19
Q

What are the main considerations for layout of highlead?

A
  • Yarding distance, deflection and landing size affect highlead productivity
  • Good landings
  • Falling boundary on slope breaks
  • no blind lead
20
Q

What are landing specs for highlead? CRITICAL

A
  • Adequate landings to deck logs spaced at 150-300 m intervals.
  • Minimum highlead landing 10-12m wide and 25-30m long.
  • loader and yarder should be side by side
  • logs at least 3/4 on landing
21
Q

What factors influence the production per turn of highlead?

A
  • volume per hectare not as important as…
  • volume per tree piece
  • production per turn directly limited by volume per piece.
22
Q

What are some key considerations for guylines and anchor points.

A
  • 6-8 guylines spaced evenly for 90’ spar
  • Angle to ground should always be less than 45 degrees (anchor at least one tower length away.)
  • anchor points must be sturdy stumps, rock anchor bolts, Or a piece of heavy equipment (tractor crawler).
23
Q

Safety Concerns for cable yarding… (4)

A
  • 2-3 men working under rigging on steep terrian
  • high lead loggers subject ot risk from moving lines rocks and runaway logs.
  • no working in the bight
  • audible whistles to communicate to entire crew.
24
Q

What is the bight?

A

The triangular area outlined by the cable between the spar, the tailhold and the corner block. Extremely risky to be in the bight.

25
Q

What are advantages of the tower system?

A
  • Very adaptable
  • steep ground (50-100%) can be harvested
  • Where site soil conditions are unacceptable for ground based equipment.
26
Q

What is the scab line system?

A

Highlead is adapted into a running skyline to distribute the load over two lines

27
Q

Why is the scab line called a running skyline?

A

The haulback doubles as a skyline but is fully mobile or “running” with the block.

28
Q

What is the main difference between a running skyline and a true skyline system?

A

The haulback line is converted to a skyline and gravity pulls the block back into the timber, unless a third drum is set up.

29
Q

How is tension controlled in a grapple yarder?

A

Drums are interlocked and there is a dial that the operator can use to increase or decrease tension on the lines.

30
Q

Whats an interlock machine?

A

A cable yarder capable of setting tension in the lines by the use of interlocking drums.

31
Q

What is unique about the grapple yarder cable system?

A

Grapple yarder is a crane rigged for a running skyline system characterized by being configured for a grapple instead of chokers.

  • Haulback doubles as a skyline.
  • Mainline closes grapple and pulls in line
  • Opening cable is interlocked and can pull in line as well as take tension off the mainline.
32
Q

What is different about the swing (grapple) yarder compared to the mobile tower?

A
  • Characterized by a gantry and boom instead of a spar tower. — -Gantry supports and adjusts boom height
  • Swing gear allows for the entire machine to swing
33
Q

Advantages of grapple yarder over tower systems?

A
  • disperses decked timber along roadside.
  • separates loading process from yarding (breakdowns have less impact)
  • can swing to landings
  • reduced crew size
34
Q

Define Cable

A

Cables hang in a straight line between harder and tailhold.

FRST 261 - Forest Harvesting Systems (11 decks)

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