Pulling Theory - Greenlee G6 Operación Manual

Cable Pulling Principles (cont'd)

Pulling Theory

This section introduces the main ideas involved with
pulling cable.
Pulling Resistance
The cable puller must overcome two types of resistance:
gravity and friction.
Gravity constantly exerts its force on the vertical
portions of the run. When the pulling force is relaxed,
gravity attempts to pull the cable downward. Friction
develops where the cable contacts the sheaves,
conduit, and tray. Friction resists any movement,
forward or backward, and tends to hold the cables in
place.
Gravity
Greenlee / A Textron Company
Friction
Conduit
Weight
of Cable
Cable Pulling Theory Illustrated
11
To accomplish a cable pull, the cable pulling system
must develop more force than the combination of
gravity and friction.
Generating Pulling Force
To generate pulling force, the capstan works as a
force multiplier. The operator exerts a small amount
of force on the rope. The cable puller multiplies this
and generates the pulling force.
This pulling force is applied to the rope, connectors,
and cable in order to accomplish the pull. The direc-
tion of force is changed, where necessary, with pulling
sheaves.
Pulling Force
6000 lb
(26.7 kN)
Tailing
Force
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G6 Turbo