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Tree Service Pros - Arborculture News Blog

Tree Service Pros - Tree Service in Lincoln, Nebraska

Tree Rigging For Removal Part 2

by David Steg on 10/21/14

 Tag Lines. These are the reins to control the

work horses. While load lines carry the weight,

proper use and placement of Tag Lines will control

swing. Without them, a log in motion can become

a potent battering ram.

KNOTS: Good knots to know are:

1. Bowline

2. Running Bowline

3. Running Bowline with a half-hitch

4. Clove Hitch

5. Clove Hitch with 2 half hitches

6. Clove Hitch with 2 half-hitches and a Figure

Eight in the tail. Use this combination on heavy

rigging. The Figure Eight will jam the half-hitches

and help prevent slip-through.

7. Timber Hitch. I only recommend this knot

for cinching up a block rope. Do not use it for

lowering limbs or skidding logs.

8. Truckers Hitch

9. Figure Eight

10. Sheet Bend

You can do a lot of work with combinations of

these knots. Remember: In general, a knot will

weaken a rope by 50%. Bowlines even more. A

good Rule of Thumb for calculating PRACTICAL,

SAFE WORKING LOADS is to:

A. use only 10% of the published tensile

strength, and

B. cut that figure in half to allow for the use of a

knot(s).

 Crotch

Natural. They're great when they are strong

enough and in the right position. When selecting a

crotch, make sure it is "U-shaped" enough to

keep from binding and strong enough to handle

the job. On a removal (only) it is a good idea to cut

the bark out of the crotch so the rope will run on

sapwood. Otherwise, you may find that the rope

will cut a groove into the bark and jam solid. Also,

the extra heat generated can fuse the rope into

something that looks like a brown candle at best

and cause a melt-through failure at worst.

 Rigged (False). Now we are rigging. False

crotching gives you the option of hanging your

ropes where you need them. Classic False Crotches

were always of rope. With synthetic line,

rope to rope contact generates too much friction/

heat and can lead to premature aging of both

rope and climber. False Crotches consist of the

following components: block (pully) and slings.

a. Block (pully). They come in all sizes and

shapes. Be sure to select one that is rated well

86 Blair: Rigging for Removal

above the ropes you will be using with it. Learn to

use, rely upon and love blocks. They will save you

money on rope, make you money on your job, and

give you a measure of precision control and

security that you wouldn't think possible without

using them.

B. Slings. You've got to hang the block to the

tree with something. Sewn slings come in sizes

from 1" to 3" and larger. Working strength can

range from 500 lbs as a choker to more than

5000 lbs. You can also rig a sling out of eyespliced

rope. Use a rope that is larger and

stronger than your bullrope. SAFETY NOTE: If

you're using a rigging rope fashioned out of an

eye-spliced 3-strand to hang a block with a timber

hitch, be careful not to take wraps into the spliced

section of rope. A sudden jolt can cause the splice

to pop apart and fail.

When selecting a sling, keep shock-loading

stress in mind and specify one that can handle the

unexpected. I recommend that all rigging components

exceed the rating of the strongest rope

employed. If your weakest link in design is the

rope, then you can be more assured of dealing

with a known factor of performance.

 Control

We've got the rope selected, we've rigged a

false crotch in the right place with a sling, next we

have to control the weight. A human body check

jammed in a crotch works, but its messy and painful.

 Wraps. There is a better way, that way is called

wraps. Human flesh doesn't hold much weight. It

has a tendency to burn and bleed, making the

rope slick and even harder to hold on to. Take a

wrap or two or three around a tree trunk or truck

bumper made of pipe. A round object to take

wraps against is called a bollard in Naval terms.

The minimum ratio is 3 to 1. So, if you were going

to take a wrap around a pipe bumper (bollard) with

a 3/4" line, the minimum diameter should be 2V*".

Whatever you use, the key is the ability to hold

and release at will and with precision.

Compared to a Lowering Device, the biggest

drawback to taking tree wraps is the difficulty in

taking up enough slack to avoid stretch.

 Lowering device. The Lowering Device is such

a remarkable tool that it has been a basic component

of many of our rigging practices. Some of our

techniques are impossible without it. With the

Lowering Device, you can be precise with your

wraps, take up all slack and even raise a piece

above an obstacle.

We've got things pretty well in hand now. We

didn't have a good enough crotch so we rigged a

block to a sling for a false-crotch. We've selected

a bull-rope large enough to do the job and in good

condition. We have double-checked to see that it

is long enough. We opted to use a Lowering

Device instead of taking trunk wraps. We're gaining

control. Are we ready to cut yet? NO!

We've got a problem. If we butt hitch, the tip is

going to hang up in some lower scaffold limbs that

we still need for later work. If we tip tie, the butt is

going to smash into the side of the house we're

trying to avoid. We'd better add another line. Now

we're Double Hitched. Ready yet? NO!

We've got the weight under control, but we

don't have any control over swing. Add a tagline

and take a wrap. Are we ready? Maybe!

 Cut. What kind of a cut are you going to make?

A. Top Cut all the way

B. Top Cut with Undercut

C. Face Cut and Back Cut

D. Undercut all the way (with a tiny top cut for

safety)

It is understood that this whole rigging scenario

is dealing with a horizontal limb.

Top Cut. Creates a hinging effect that causes

the tip to drop as the cut opens up. Depending

upon the type of tree and whether or not it is alive,

dying, dead or rotten, it is going to react in one of

the following ways:

1. Break over nicely and hold on a hinge. With

ash or pine, that hinge might be a bundle of

splinters.

2. Break over nicely until the hinge lets go and a

long barber chair tear rip along the standing section

of limb. On elm, it could tear all the way to the

ground.

3. Snap off without warning, dead oak. KNOW

YOUR WOOD.

Top cut With an Undercut. The old 1-2-3. It

won't tear, but it can "cock" a tremendous

amount of energy if it hangs up and holds without

falling free in one smooth motion. If that happens,

be prepared for a pretty good jolt when it let's go.

Journal of Arboriculture 15(4): April 1989 87

The old tree toppers in logging used to let them

hang up on purpose just so they'd have a good

ride to brag about after work. Also, using an axe

and a handsaw made it harder to get a clean letoff.

Face Cut with a Back Cut. Even on a horizontal

limb, you can make use of a notched undercut and

then a top cut. You'll gain a controlled drop into

the face and a more or less predictable letoff.

Undercut. When using a crane or the Lowering

Device, the Undercut Only works very well. With

all slack taken up, the rigging operator lifts the

piece up off and away. Done properly, there is no

drop, and no pinching on the saw. You have to be

extremely careful when working with a crane. Too

much tension can cause the piece to barber chair

off unexpectedly, fly into the air with more lift and

greater force than anticipated. EASY DOES IT. A

"tiny" kerf laid into the top of the limb is a good

idea to insure a clean lift off.

 Hardware Glossary

We've touched on the basics. Herein is a list

and definition of some special tools that come in

handy.


Nebraska Arborist Association
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