Pulling force is the number that ultimately defines which hydraulic puller you buy. But the question "how much pulling force do I need?" has a more nuanced answer than most buyers expect — and it is not simply "the higher the voltage, the bigger the machine."
The Common Pulling Force Classes
Hydraulic pullers are typically offered in a ladder of capacities: 40, 60, 90, 120, 150, 180, 220, 280 and 380 kN. Each step up adds pulling force and, usually, rope winch capacity and machine weight. Choosing the correct step is the whole exercise.
| Class (kN) |
Typical Use |
| 40–60 |
Single conductor and OPGW, short sections, distribution lines |
| 90–120 |
Twin-bundle conductor on 110–220 kV lines |
| 150–180 |
Four-bundle and long-section transmission work |
| 220–380 |
Heavy four-bundle and large-section EHV projects |
What Actually Changes the Required Force
Voltage level is only a rough proxy. The real drivers are:
- Conductor weight and cross-section — heavier, larger conductors need more force to lift off the ground and ride the blocks.
- Bundle number — each additional sub-conductor multiplies the total load.
- Stringing section length — longer pulls mean more friction and more total load.
- Terrain — steep or undulating ground increases the effective load far beyond a flat-land estimate.
- Friction and angle changes — every corner tower and block adds friction losses.
A twin-bundle 220 kV line over flat ground may need far less force than the same conductor over hilly terrain, so it is a mistake to size the machine on voltage alone.
Intermittent vs Continuous Pull
Every puller has two ratings that buyers must read carefully: intermittent pull (peak, short-duration force) and continuous pull (sustained force for the whole pull). A machine in the 220 kN class, for example, may offer a high intermittent figure that only applies briefly, while its continuous rating is what actually matters for a long 500 kV section. Always size the machine so that the continuous rating exceeds your anticipated working load with a healthy margin.
Getting to Your Number
Start by estimating the total load from conductor weight, bundle number, section length and terrain, then add a safety margin, and finally match that figure to the nearest hydraulic puller class. Browse the Hydraulic Puller range to compare intermittent and continuous ratings side by side, then confirm with the manufacturer using your actual project data. The right pulling force is the one that finishes the section without stalling — and without over-speccing the machine.
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