At The Capstan - Textron Greenlee Ultra Tugger 15000-22 Manual De Instrucciones

Cable Pulling Principles (cont'd)
Cable Pulling Forces (cont'd)

At the Capstan

The capstan acts as a force multiplier . The operator
exerts a small amount of tension, or tailing force, on the
rope; the capstan multiplies this force to pull the cable.
The resultant force depends upon the number of times
the rope is wrapped around the capstan, as shown in the
formula below.
Pulling Force = Tailing Force x e
Where: e = the natural logarithm, or 2.7183
µ = the coefficient of friction between the
rope and the capstan *
ø = the number of degrees of wrap of rope
around the capstan
* The average value for the coefficient of friction when
double-braided composite rope is pulled over a clean
dry capstan is 0.125.
Greenlee / A Textron Company
Ultra Tugger ®
0.0175µø
The Capstan as a Force Multiplier
Pulling Force: 35.6 kN (8000 lbs)
16
Cable Puller and Pulling Packages
The following table is based on the formula above.
The input, or tailing force, is constant at 44.5 Newtons
(10 lbs). Increasing the number of wraps increases
the pulling force.
Number
Operator's of Wraps
Tailing Force of Rope
44.5 N (10 lbs)
44.5 N (10 lbs)
44.5 N (10 lbs)
44.5 N (10 lbs)
44.5 N (10 lbs)
44.5 N (10 lbs)
44.5 N (10 lbs)
This table shows how the capstan acts as a force
multiplier. Because the coefficient of friction depends
upon the condition of the rope and capstan, this formula
cannot determine an exact amount of pulling force.
Tailing
Force
4455 Boeing Dr. • Rockford, IL 61109-2988 USA • 815-397-7070
Approximate
Pulling Force
1 93.4 N (21 lbs)
2 213.5 N (48 lbs)
3 474.9 N (106 lbs)
4 1043.8 N (233 lbs)
5 2293.7 N (512 lbs)
6 5048.9 N (1127 lbs)
7 11.1 kN (2478 lbs)