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ROPES
Which type of Rope will serve you best?
In your selection of the best rope to serve your needs, knowledge
of the various types of rope available to meet different conditions is
important. In determining the rope best suited for your requirements,
the following factors are of special importance:
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Strength lifts the load and does the work. It takes good fiber or filaments to give full strength.
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Abrasion Resistance assures extra life on pulleys, winches and other wearing or torsion conditions
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Water Repellency keeps rope from swelling when wet, prevents it from becoming stiff and unmanageable.
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Flexibility makes rope agile and easy to handle under all working conditions.
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Safety is of particular importance in falls, slings, hoisting, mooring and towing lines.
Know your rope requirements.
The correct size is important. Using undersized rope causes undue
strain on the rope. Proper selection of the right rope size is the
greatest factor in getting full use and long life from your rope. In
addition to size, other factors such as type of lay and special fiber
treatment
will determine the selection of rope. Most industries making
regular use of rope have selected certain types as best suited to
perform specific jobs. In some cases, special purpose ropes have been
developed to meet particular needs.
Generally, the proper size and type of rope can be specified from
your past experience and the recommendations of your supplier.
ROPE CONSTRUCTION
Popbros Industries can makes 3- Strand, 4- Strand, or 8- Strand Plaited
Ropes as per the requirements.
3-Strand ropes are preferred on most applications because of its
flexibility, knotability, and ease in handling. They come in an easy-to-
splice medium lay, however can be ordered to conform to specific lay
requirements either softer or harder. 4-Strand ropes have a
slightly firmer lay and provides a rounder rope with more outside
surface and more traction on sheaves and objects to be turned or
gripped. It is available in various core constructions depending on the
rope's application. 4-Strand Manila ropes are approximately 7% heavier
than 3- Strand and have a breaking strength approximately 5% less.
8-Strand plaited ropes have four left-hand laid strands and four
right-hand laid strands, paired off parallel and woven together. Used
mostly for marine applications, its neutral (or balanced) construction
provides excellent hockling resistance. It is available in 5" to 15"
circumference (or 1-5/8" to 5" diameter).
TREATMENT(S)
All Natural Fiber Ropes are lubricated with a water
repellent treatment that resists moisture, mildew, and rot. The
lubrication also guards against internal chaffing and wear. Upon
request, ropes may be treated with Copper Quinolinolate, Copper
Napthanate, Tar, Graphite impregnated, or Tallow treated. These
treatments are generally for the added protection of fibers against rot
and mildew.
Proper Use of Rope
INSPECTION. New rope should be thoroughly inspected throughout its
entire length before it is placed in service to determine that no part
of it is damaged or defective. After it is placed in service, rope
should be inspected at least every thirty days under ordinary
circumstances; more often if it is used to support scaffolding or other
supports upon which men work. If it is exposed to acids or caustics, it
should be inspected daily. Inspection should include examination of the
entire length of rope for wear, abrasion, broken or cut fibers,
displacement of yarns or strands, discoloration or rotting. To inspect
the inner fibers, the rope should be untwisted in several places to make
sure the inside yarns are bright, clear and unspotted. The
specification tables show breaking strengths and safe working loads.
Rope loaded to over 75% of its breaking strength will be permanently
injured. Damage from this cause may be detected by examining the inside
threads which will be broken to an extent governed by the amount of the
overload. Such damage may also be determined by the reduced diameter of
the weakened section of the rope. Care should be taken to prevent
kinking a rope. Even a moderate strain may over-stress the fibers at the
point of the bend, producing a serious defect and one that may be
difficult to locate.
CARE OF ROPE. If rope becomes muddy or dirty, it may be washed
with cold water and moderate hose pressure, but never with seam. Any
grit or dirt that remains may be shaken out after the rope has dried.
The use of wet rope or rope reinforced with metallic strands is
dangerous near power lines and other electrical equipment. A wet rope
should never be left where it may freeze. With proper care, lubrication
other than that in the new rope is unnecessary. Sharp bending of the
rope around objects too small for the rope, or over sharp corers should
be avoided because these cause extreme tension or abrasion on the
fibers/filaments. Be sure the bend is sufficient for the rope size;
sharp corners or rough surfaces should be padded.
EASIER HOISTING WITH LESS EFFORT NEEDED. Tackle lifts extra
weight, but use the proper sheave size. Blocks and tackle reduce the
power needed to hoist or pull a given load. The mechanical advantage to
be gained will vary with the number of sheaves employed in tackle
combinations. The illustrations and data represent standard practice in
the use of block and tackle. The selection of correct rope size for
specific applications is an important consideration for maximum
efficiency and dependability.
ROPE SLINGS. Small angles increase rope stress. Allow for
sling angles. The breaking strength of rope is based on direct pull
along a single length of rope. When slings, using two or more legs to
carry the load, are properly employed, the rope's safe working load is
substantially increased. However, as illustrated below, the load factor
on each leg of the sling is greatly increase as the sling angle becomes
smaller. Therefore, the use of slings requires certain precautions as
well as a knowledge of safe working loads permissible. For best results,
sling angles should never be more than 90 degrees - rarely less than 45
degrees.
SPLICE ROPE FOR PERMANENCE. A splice is stronger than a knot.
The strongest way to join two ropes, or to make a sling or endless rope,
is to splice it correctly. Even the most efficient knots will reduce
rope strength to as much as 50%, while a carefully made splice may have
up to 95% of the strength of the rope being spliced. A short splice
gives the strongest coupling however, it doubles the rope size and is
not suitable where rope must run through pulleys or sheaves on a block.
For such purposes, a long splice, with up to 90% strength efficiency, is
used.
Don't weaken your rope. Follow these rules for good care
ROPE CARE & SAFETY
GOOD ROPE CARE - BETTER ROPE SERVICE. or the service that should
be expected from good rope, and for the safety of men and materials,
rope should be handled and used with care. By following these points in
rope selection, handling and storage, it will remain dependable and safe
over long periods.
SELECT BEST ROPE FOR THE JOB. Economy as well as service
depend on the right size and quality for the work. Allow a safety factor
of at least five to determine safe working load for new rope. As rope
ages, the safety factor should be increased.
REMOVE FROM COIL CORRECTLY. Always take rope from coil in this
way to avoid distorting the lay of the rope. First, lay the coil flat
with inside end of rope nearest the floor or deck. Loosen lashings and
coverings. Then reach down through center of coil and pull rope up
through from inside of the coil.
STORE ROPE PROPERLY. Rope should always be dry before storing;
storing wet rope causes mildew and rot. A cool, dry room with free air
circulation makes ideal storage. If necessary to store on metal or
concrete floors, protect the rope with planking to prevent contact with
the floor.
REVERSE ENDS OF ROPE. Changing ends of the rope regularly when
used in tackle, permits even wearing and assures longer useful life. If
a short section shows undue wear or damage, cut out the worn section
and splice the rope for best service. Then make sure that the cause for
the excess wear is corrected.
KEEP ROPE CLEAN. Dragging rope on the ground or over rough,
gritty surfaces allows abrasive particles to work into the rope and
weaken the fibers. If rope becomes muddy or dirty, it should be washed
and dried thoroughly before storing.
KINKS CAUSE ROPE FAILURE. Prevent kinks which cause permanent
damage and weakening of the rope. If kinks should form, or if rope is
continually twisted in one direction, as over a winch, remove kinks or
restore balance in the rope by throwing in twist in opposite direction.
PROTECT ROPE FROM CHEMICALS. Acids and their fumes, alkalis,
oils, paints and barn-yard mud are injurious to vegetables fibers and
will quickly damage rope. protect from these agents wherever possible
and remember that clean, dry rope is the best assurance of long rope
life.
AVOID SUDDEN STRAINS. Jerking or sudden strain may cause
failure of a rope normally strong enough to handle the load safety. A
steady, even pull will assure full strength from rope. This is
especially important when using slings or tackle which may multiply
strain and power. |