会社のニュース How to Select Cable Conveyor Spacing for Long Distance Underground Cable Installation

On a long underground route, cable conveyors replace brute pulling force with distributed assistance. Space them too far apart and the cable sags and rubs; space them too closely and cost and setup time balloon. Selecting the correct cable conveyor spacing for long distance underground cable installation is a balance of cable weight, allowable tension and the capability of the cable pulling equipment at the head end.

Why Conveyors Are Used at All

A single head-end puller on a multi-kilometre duct must overcome the friction of the entire cable. Distributed conveyors support the cable and add small forward forces along the route, so the head-end tension stays within the cable's allowable limit. The spacing between them decides how evenly that support is applied.

The Spacing Logic

Spacing is set by two limits: the tension the cable can tolerate and the sag that appears between support points. In practice, spacing is chosen so the additional tension contributed between conveyors stays small compared with total allowable tension, and so the cable never contacts the duct floor.

Friction is the wildcard. A well-lubricated duct and a smooth cable sheath can cut the friction coefficient dramatically and allow wider conveyor spacing, while a rough duct or a stiff, cold cable demands closer spacing. Because friction is hard to predict from drawings alone, experienced crews often start with conservative spacing and widen it only after measuring the actual pulling tension on the first sections.

Match the Head-End Puller to the Route

The head-end machine still sets the achievable tension. A puller with a clear relationship between maximum pull and matching speed lets the operator tune the pull as conveyors take up load:

Choosing and Placing Conveyors

Conveyors come in straight-line and corner versions. Straight conveyors sit on the trench floor and support the cable between bends; corner conveyors are angled to follow the route around a curve. Placing a conveyor at the start of each straight run and at each bend keeps the cable supported everywhere. The conveyor speed must be synchronised with the head-end puller, because a conveyor running slightly fast pushes the cable and one running slow drags against it, and either mismatch adds friction rather than removing it.

Layout Planning Checklist

1. Calculate total friction and pull tension for the full route.
2. Divide the route into segments short enough to keep local tension within limits.
3. Place a conveyor at the start of each segment and after every bend.
4. Keep the spacing consistent so no single gap is unsupported.
5. Set conveyor force low — they assist, they do not pull.
6. Keep all conveyors synchronised in speed with the head-end puller.

Matched equipment makes the plan work. The 140 kN 4 km/h hydraulic wire puller provides the head-end force, while the companion 24 mm rope hydraulic puller-tensioner handles the tension side. The full Cable Pulling Equipment range covers units sized for every segment.

FAQ

How far apart should cable conveyors be?

Close enough that the cable never sags to the duct floor and the tension added between supports stays small. Long, straight, well-lubricated runs allow wider spacing than curved or rough ones.

Do conveyors replace the main puller?

No. Conveyors assist and support; the head-end puller still provides the primary force. They reduce the load the puller must overcome.

What single factor most affects spacing?

Cable weight per metre and duct friction. Heavier cable and higher friction demand closer spacing.

Get a Selection Recommendation

Tell us the route length, number of bends, cable diameter and weight per metre, and we will recommend conveyor spacing and head-end puller rating for the whole run.