Pulling very large diameter cables (e.g., HV/EHV power cables) or multiple cables simultaneously through underground conduits presents significant challenges due to immense weight, friction, and the critical need to prevent damage. Specialized techniques and robust equipment are essential.

I. Techniques for Large Diameter / Multiple Cable Pulls:

• 1. Meticulous Route Planning and Conduit Design:

  • Minimize Bends: Design routes with as few bends as possible, and ensure any necessary bends have the largest possible radius to reduce sidewall pressure and friction.

  • Conduit Sizing: Select conduits with ample internal diameter to comfortably accommodate the cable(s) and allow for a sufficient amount of lubricant. For multiple cables, ensure the sum of their diameters allows for sufficient space within the conduit.

  • Conduit Quality: Use high-quality, smooth-walled conduits (e.g., large diameter HDPE, concrete-encased duct banks) free of burrs or obstructions.

• 2. Intermediate Pulling & Setup:

  • Intermediate Manholes/Vaults: For very long runs or those with significant changes in direction, strategically placed intermediate manholes or vaults allow for "segmenting" the pull. This involves pulling the cable in sections, resetting the pulling equipment, or even using an intermediate puller-feeder.

  • "Figure-8" Method: For very long lengths pulled in segments, the cable can be "figure-8'd" on the surface at intermediate points, allowing it to be pulled from both ends of the segment into the conduit. This reduces handling stress on the cable.

• 3. Continuous and Controlled Lubrication:

  • High-Volume Lubricant Application: Much larger quantities of high-performance, compatible cable lubricant are required. It must be applied continuously and generously at the feeding end and often at intermediate points (e.g., manholes).

  • Lubricant Pumping Systems: Automated pumping systems can inject lubricant directly into the conduit ahead of the cable.

• 4. Pre-calculated Pulling Tensions:

  • Sophisticated Software: Using advanced pulling software to accurately model and predict maximum pulling tensions and sidewall pressures for the entire pull, considering cable weight, conduit type, bends, and lubrication. This determines the necessary equipment capacity.

• 5. Heat Management During Pull:

  • Controlled Speed: Maintaining a slower, consistent pulling speed helps manage heat generated by friction, especially for very large cables or long runs.

  • Monitoring Cable Temperature: In critical applications, monitoring the cable's surface temperature during the pull can provide valuable feedback.

II. Specialized Equipment:

• 1. High-Capacity Hydraulic Cable Pullers: Our robust hydraulic pullers are engineered for immense pulling forces (tens of thousands of pounds or kN). They feature:

  • Powerful Engines/Motors: To deliver consistent, high torque.

  • Automated Tension Control: Integrated load cells and intelligent controls prevent exceeding MAPT.

  • Large Capstans/Drums: Designed to handle large pulling ropes without slippage or damage.

• 2. Cable Feeding Equipment:

  • Powered Cable Feeders: Positioned at the entry point of the conduit, these units actively push the cable into the duct, significantly reducing the pulling force required from the other end. This is crucial for heavy, stiff cables and long pulls.

  • Large Reel Stands & Trailers: Robust stands capable of safely supporting and unwinding massive and heavy cable reels (often weighing many tons).

• 3. Specialized Cable Rollers and Guides:

  • Heavy-Duty Rollers: Larger, more robust rollers with smooth, wide sheaves designed to support the immense weight of large cables and maintain the minimum bend radius at all turns and entrances.

  • Manhole Sheaves/Guides: Specifically designed to guide the cable smoothly around corners within manholes and vaults, minimizing sidewall pressure.

• 4. Heavy-Duty Pulling Grips/Eyes:

  • Swivel Pulling Eyes: Robust, high-strength pulling eyes specifically designed for large cables, often integrated with a swivel to prevent cable twisting. They attach securely to the cable's strength member or conductors.

  • Basket Grips: Heavy-duty, woven mesh grips for multiple cables or armored cables, designed to distribute pulling force evenly along a larger section of the cable.

• 5. Bore Gels & High-Performance Lubricant Pumps: For HDD applications, specialized drilling fluids and high-volume pumps are used to lubricate the bore and facilitate the pull-back of large conduit bundles or cable.

Our company specializes in providing this comprehensive range of high-capacity and precision-engineered underground cable pulling equipment, ensuring that even the most demanding large-scale or multi-cable installations are performed safely, efficiently, and to the highest quality standards.