Pulling Theory - Greenlee 2001 Instruction 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
Cable Pulling Theory Illustrated
Friction
Conduit
Weight
of Cable
2001-Series Easy Tugger Cable Pullers
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 direction
of force is changed, where necessary, with pulling
sheaves.
Pulling Force
8.89 kN
(2000 lb)
11
4455 Boeing Dr. • Rockford, IL 61109-2988 USA • 815-397-7070
Tailing
Force