Predicts the pulling tension a cable builds up as it's winched through a multi-segment conduit or duct route \u2014 straight sections via friction, bends via the exponential capstan equation \u2014 and checks it, along with sidewall bearing pressure and the classic 3-cable jam ratio, against manufacturer limits before a pull is attempted in the field.
Standards followed
IEEE 1185 (cable pulling tension/capstan equations)
What it can do
- Segment-by-segment tension buildup across up to 6 pull-route segments (straight horizontal/vertical, or bends) in actual pull order.
- Capstan-equation tension multiplication at each bend, from bend angle and friction coefficient.
- Sidewall bearing pressure at each bend, checked against the cable's rated limit.
- 3-cable jam ratio (conduit ID รท cable OD) with a check against the published 2.6-3.2 jamming danger zone.
Example problem
A pull route has two 50ft horizontal straight sections and one 90ยฐ bend of 2ft radius, with friction coefficient 0.35 and cable weight 3.3 lb/ft.
- First straight section: tension builds from friction alone โ 57.75 lbf.
- Second straight section (before the bend): tension continues to build โ 115.5 lbf.
- At the 90ยฐ bend, the capstan equation (T_out = T_in ร e^(fรฮธ)) multiplies tension to 200.146 lbf.
- Peak sidewall pressure at the bend = T_out / radius = 200.146 / 2 = 100.073 lb/ft.
Final tension 200.146 lbf and peak sidewall pressure 100.073 lb/ft โ both comfortably pass typical 5,000 lbf / 300 lb/ft limits. A separate 3-cable jam-ratio check (4in conduit ID / 1.45in cable OD = 2.759) falls inside the 2.6-3.2 danger zone, flagging a real jamming risk worth mitigating.
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