Single Conductor Pulley Blocks are used for single conductor or Optic fiber cable stringing on overhead transmission lines. The sheave of pulleys can be made in aluminum alloy or nylon , optional lined with neoprene. All the sheaves are mounted on ball bearings. The frame is made in galvanized steel.

Single conductor pulley with aluminum sheave or nylon sheave

Application: It is suitable to string stranded aluminum and ACSR conductors on tangent structures. Compression sleeves, swivel connectors, and pulling rope connectors can pass through the groove. The sheave is made in aluminum alloy or high strength nylon. The big size 508mm, 660mm aluminum alloy sheave can be lined with neoprene. The big size 660mm, 822mm, 916mm, 1040mm nylon sheave can be lined with neoprene.

Note:

1.       Hook fitting, round eye fitting, and clevis fitting are optional, please specify when ordering. Customized blocks could be supplied on request.

The data in the model means the outer diameter of sheave X width of sheave (mm).

2. All the sheaves are mounted on ball bearings. The frame of blocks is made in galvanized steel.

Workshop for making high strength MC nylon sheaves.

Sheaves:

1.    Aluminum alloy sheaves lined with neoprene

2. Nylon wheels lined with neoprene

Workshop for production and assembly of conductor pulleys

Overhead Transmission Line Large Diameter Conductor Pulleys

Application: It is suitable to string stranded aluminum and ACSR conductors on tangent structures. Compression sleeves, swivel connectors, and pulling rope connectors can pass through the groove. The sheave is made in aluminum alloy or high strength nylon. The big size 508mm, 660mm aluminum alloy sheave can be lined with neoprene. The big size 660mm, 822mm, 916mm, 1040mm nylon sheave can be lined with neoprene.

Installation of distribution conductors can  be made one conductor (phase) at a  time; however, it is possible to install all three phases plus neutral at one time with  a  multi-conductor  tensioner and a running board. Insulated conductors may be in the form of three or four conductors with a messenger wire twisted together as a bundle. This bundle  is  usually installed on the structures in the same manner as one conductor.

The slack stringing method  is not recommended for installation of transmission line conductors, because surface damage to or contamination of the conductor using this installation process can be quite high, causing corona losses and excessive radio, TV and communication interference.

The method shall be used for installation of distribution line conductors where applicable; anyway, this method is not recommended in areas where high induction is possible.

There are two commonly used methods for slack stringing.

a) Stationary reel method

This method is when the conductor reels are located at one end of the pull section. The conductor is dragged along the ground of the right of way by means of  a  towing vehicle (see Figure 5a).

b) Rolling reel method

Another variation of the slack stringing method is when the reels are towed along the right of way on a trailer behind a towing vehicle, and the conductor is deposited on the ground (see Figure 5b).

The conductor reels are held in reel stands either placed on the ground or  mounted on  a  trailer. These stands are designed to support the reel on a shaft, permitting it to turn as the conductor is pulled out. Usually a braking device is  provided to  prevent  overrunning of  the reel when the pulling is stopped.

When the conductor is towed past each supporting structure or tower, the towing vehicle is stopped and the conductor placed in stringing blocks attached to the structure before  proceeding to the next structure.

This method is chiefly applicable to the construction of rural distribution lines, where the line right of way is easily accessible to a towing vehicle. The method is not practical to use in congested urban locations where hazards exist from traffic or where there is danger of contact with energized circuits. Nor is it practical in mountainous regions where the towing vehicle cannot proceed along the right-of-way.

Shipment

1. The blocks will be shipped in plywood case , steel frame case or container

2. We will ship the products within one month normally after receiving the payment.

3. Stock is available for standard product.

The tension stringing method is applicable for both transmission and distribution lines, and  shall be considered the state of the art of the conductor installation methods.

This method is illustrated in Figures 6a to 6d for distribution lines and Figures 6e to 6m for transmission lines.

Using this method, the conductor is kept under tension during the stringing process to  keep  the conductor from contacting the Earth surface or other obstacles between towers since this will cause conductor surface damage. The tension in the conductor also allows it to pass over energized circuits, railway or major road crossings, etc. without contacting them.

For multiconductor per phase lines, the tension stringing method requires the installation of a light synthetic or metallic pilot rope into the stringing blocks. This is normally done using the slack stringing stationary reel method by either a towing vehicle or a  helicopter  or  a  drone. The pilot rope is used to pull in a heavier pulling rope, and the pulling rope is then used to pull  in the conductors.

For single conductor per phase installations, the pulling rope may be installed directly with a towing vehicle or by helicopter eliminating the use of a pilot rope completely.

All the subconductors of each bundle are strung at the same time and with the same tension applied, to avoid difference sag behaviour once installed.

Package

1. The single conductor pulley will be loaded in container.

2. It also can be packed in plywood case or steel frame case.

Payment

1. We accept T/T and L/C.

2. Please send swift copy of T/T if you arrange payment by T/T

3. Please send us the L/C draft to us before issue L/C.

Special Test Structure of Pulley Blocks (The only one of National Powr Company):

Why choose us:

1. High quality and competitive price

2. Leading and biggest manufacture for stringing equipment and tools in China.