новости компании о How to Choose the Correct Sheave Diameter for Conductor Stringing Blocks

The sheave diameter of a stringing block decides whether a conductor arrives at the tower smooth or kinked. Too small and the conductor bends tighter than its safe limit; too large and the block becomes heavy and hard to handle. Choosing the right sheave diameter for conductor stringing blocks is therefore a balance between conductor protection and practical handling.

The Rule of Thumb for Sheave Diameter

The accepted field rule is that sheave diameter should be at least 15–20 times the conductor diameter for aluminium and aluminium-alloy conductors, and higher for large bundles. Below that ratio the conductor surface is permanently deformed as it passes over the sheave. The groove radius must also match the conductor so that contact is over an arc, not a point.

Matching Diameter to Conductor and Load

A block is defined by three numbers: the sheave size, the rated load and the conductor range. Buyers should compare all three against the project's largest conductor. The Galaxy SHWN series five-wheel block illustrates the data that matters:

Reference Specification — Five-Wheel Nylon Block

For lighter single-conductor work, the Galaxy SHCSN-2 aluminium-wheel block shows how a smaller block still carries a defined rating:

Sheave Groove Geometry Matters as Much as Diameter

Diameter sets the bend radius, but the groove profile sets the contact pressure. A groove that is too narrow pinches the conductor; one that is too wide concentrates load on a single point. The groove radius should match the conductor's outer radius so the conductor rests over a broad arc. For bundle blocks the wheels are set apart so each sub-conductor stays in its own groove and the bundle is not flattened. When operators report conductor marking despite a generous sheave diameter, the groove profile is usually the real cause.

Light versus Heavy Conductor Blocks

Conductor size drives the whole selection. A light single conductor up to 240 LGJ needs only a compact block, while a large bundle up to 400 mm² needs a multi-wheel block with the rated load to match. Oversizing the block adds weight and cost without benefit; undersizing it overloads the wheels and the conductor. The practical approach is to size the block to the largest conductor on the line and confirm the rated load against the maximum stringing tension with margin.

Selection Checklist

1. Confirm the maximum conductor diameter on the line.
2. Set the minimum sheave diameter at 15–20 × conductor diameter.
3. Match the groove radius to the conductor profile.
4. Check the rated load against the stringing tension and bundle weight.
5. Choose the wheel material — nylon for lighter, aluminium for higher loads.
6. Confirm opening or side-panel design allows easy conductor placement.

The 5 × 508 × 75 mm nylon pulley block suits large bundles up to 400 mm², while the 20 kN stringing block covers single conductors up to 240 LGJ. Browsing the full Conductor Stringing Blocks range confirms both ends of the size spectrum.

FAQ

What is the minimum sheave-to-conductor ratio?

A common minimum is 15:1, with 20:1 or higher preferred for large or sensitive conductors. Always confirm against the conductor maker's data.

Does sheave material affect conductor damage?

Yes. Nylon wheels are gentle and light, aluminium wheels handle higher loads. Both must have a groove radius matched to the conductor.

How many wheels does a bundle need?

One wheel per conductor in the bundle, plus reserve capacity, so the tension is shared and each sub-conductor stays in its own groove.

Get a Selection Recommendation

Share your conductor type and diameter, bundle configuration and maximum stringing tension, and we will specify the sheave diameter, groove radius and rated load you need.