Elliott Digger Derrick - Knots; Use of Slings with Winch Lines; Sharp Cutting Edges

Synthetic Rope Usage EEC-0060 V1.2
Synthetic Rope Usage,
Inspection, and Retirement
Knots
While it is true that a knot reduces rope strength, it is also true that a know is a
convenient way to accomplish rope attachment. The strength loss is a result of the tight
bends that occur in the know. With some knots, ropes can lose approximately 50
percent of their strength; however, this number can be higher or lower based on rope
construction and fibers used. It is vital that the reduction in strength by the use of knots
be taken into account when determining the size and strength of a rope to be used in an
application. To avoid knot strength reduction, it is recommended that a rope be spliced
according to the manufacturer’s instructions. Splice terminations are used in all ropes to
determine new and unused tensile strengths. Therefore, whenever possible, spliced
terminations should be used to maximize the rope strength for new and used ropes.
Use of Slings with Winch Lines
The winch line itself should not be used as a choker to pick up a pole or other
objects. The hook attached on the end of the winch line can cut deeply into the rope
itself. We recommend a separate line, sling or strap be used as the choker and not the
winch line itself.
Sharp Cutting Edges
Winch lines should not be exposed to sharp edges and surfaces, such as metal
burrs on winch drums, sheaves, shackles, thimbles, wire slings, etc. Winch lines are
made from synthetic fibers and can be cut or damaged by sharp edges. When installing
winch lines on old truck units, great care must be exercised to assure that the rope is
not coming in contact with hardware that has been scored and chewed by previously-
used wire lines. Sheaves, shackles, thimbles, etc., should be replaced in most cases.
Other metal surfaces should be carefully examined and dressed if necessary.
Abrasion Protection of Line
Depending on manufacturer specifications, most ropes have an outer jacket of
polyester, which has a relatively high degree of resistance to abrasion and melting.