Reeling Cable Explained: How It Works in Vertical and Horizontal Reeling Applications
Reeling cablesare custom-made cables designed specifically for winding and unwinding from either an electrically or mechanically driven spool. In contrast to regular cables, reeling cables have the ability to retain their structure even when being wound and unwound continuously and, at the same time, supply power or data to movable machines. Reeling cables play a vital role in industries that involve heavy machinery with mobility but without tangling of cables, including shipping ports, mines, and factories.
This article examines the two primary modes of cable reeling—horizontal and vertical—to provide a comprehensive framework for cable selection and maintenance.
Reeling Cable in Horizontal Reeling Applications
Horizontal reeling is the most common application for mobile electrification. In this setup, the equipment moves along a fixed path, such as a rail or a flat ground surface, while the cable reel (usually mounted on the machine) manages the cable length. This configuration is standard for Ship-to-Shore (STS) cranes, Rail-Mounted Gantry (RMG) cranes, and large-scale bulk-handling conveyors.
1. Mechanics of Horizontal Movement
The process of horizontal reeling normally uses two types of cable feedings, namely end feed and center feed. For an end-fed operation, the driving force of the cable will be provided at the end of the travel path, where the entire length of the machine's travel will need to be fed into the cable. In a center-fed process, the drive will be provided midway, giving room to spread the cable in both directions and reducing the amount of cable length to half compared to the former. The problem with the center-fed system is that the cable experiences crossover in the middle of the reel.
In the horizontal motion, the dominant force that acts on the cable is tensile stress due to the pulling action of the reel. Since the cable lies on a tray or on the ground surface, there is minimal gravitational effect on the cable.
2. Technical Parameters and Practical Advice
In the case of the horizontal reeling method, consideration has to be made concerning the minimum bending radius. This is simply the lowest point where the conductor may be flexed without causing damage to the cable core itself or the jacket. In the case of dynamic reeling, it is standard that the minimum bending radius should be 8 to 10 times larger than the OD of the cable. In the case of a drum that is too small, cold-working of the conductors occurs.
3. Industry Insight: Preventing Reverse Bending
A frequent cause of premature cable failure in horizontal systems is reverse bending. This occurs when a cable is wound onto the reel in one direction but is pulled or stored in a way that forces it to bend in the opposite direction. This stresses the internal layers of the cable. To prevent this, always ensure the cable transitions from the delivery spool to the equipment reel in a continuous arc without S-bends.
Furthermore, tension control is paramount. For high-speed applications (reaching up to 200 meters per minute), the reel must have a sophisticated torque control system. If the tension is too low, the cable will slacken and potentially get caught in the machine's wheels. If the tension is too high, the conductors will stretch, leading to a reduction in cross-sectional area and subsequent overheating or electrical failure.
Reeling Cable in Vertical Reeling Applications
Vertical reeling applications are mechanically more demanding because the cable must support its own weight in addition to the forces of acceleration and deceleration. This setup is primarily used in hoist units, spreader systems for container handling, and deep-well pumps.
1. Structural Reinforcements for Gravity
In a vertical application, the cable hangs suspended from a high-point reel. As the "spreader" or hook moves downward, the weight of the suspended cable increases. To manage this, vertical reeling cables are built with a central tensile member. This is a core made of high-strength materials, such as Aramid (Kevlar) or specialized polyester braids, designed to take the brunt of the hanging weight so the copper conductors do not stretch.
Another critical factor in vertical movement is torsion (the twisting of the cable around its longitudinal axis). When a hoist moves at high speeds, the cable can begin to spin. Without proper design, this twist would cause the internal conductors to "bird-cage" (unravel and push through the outer jacket). Consequently, vertical reeling cables include an anti-torsion braid, usually integrated between the inner and outer jackets, to lock the cable’s internal components in place.
2. Maintenance and Selection for Vertical Systems
Selection for vertical systems must prioritize the "suspended length" rating provided by the manufacturer. If a cable is rated for 50 meters of vertical suspension and is used for 70 meters, the internal reinforcements may fail, leading to a catastrophic drop.
3. Practical Tip: The Use of Cable Grips
In port operations, it is common practice to use cable grips (often called "socks" or "mesh grips") at the fixed connection point. These grips distribute the hanging weight over a large section of the cable jacket rather than concentrating the stress on the electrical terminals. This prevents the "creeping" of the conductors inside the jacket.
Regular inspection of the reel's winding pattern is also necessary. Because vertical cables are often under higher tension, "piling" (where the cable winds unevenly on one side of the drum) can create massive localized pressure. This pressure can crush the inner layers of the cable, leading to intermittent short circuits that are difficult to diagnose.
Key Differences and Practical Selection Guide
Choosing between a cable designed for horizontal use versus vertical use is not always interchangeable. Below is a breakdown of the primary distinctions and decision-making factors.
Feature | Horizontal Reeling | Vertical Reeling |
Primary Stress | Tensile pull & surface abrasion | Self-weight & high torsion |
Internal Design | Flexible braiding, focus on bend | Center strength member (Aramid) |
Torsion Support | Moderate | High (Anti-torsion braid required) |
Jacket Material | High abrasion resistance (PUR/Rubber) | High tensile strength & weather resistance |
Typical Speed | Up to 200m/min (Travel) | Up to 150m/min (Hoist/Lift) |
Selection Logic for New Professionals
- Consider the Motion: For applications where the machinery travels 100m on the rail, look at the tensile strength and abrasion-resistant qualities of the cable. If the machine raises an object 30m in height, consider the torsion resistance and core strength.
- Consider the Environmental Factors: Cables used in reels can be exposed to extreme conditions. Check that the cable can function well under your specific conditions. Rubber jacketing made from synthetic material (such as neoprene or polychloroprene) can withstand chemicals and oils, whereas PUR jacketing has greater abrasion resistance and flexibility in low temperatures (-40°C).
- Confirm VFD Compatibility: Most reels utilize VFD systems nowadays. The cables should be shielded and meet EMC standards to avoid electrical interference between any nearby sensors or communication cables.
When it comes to controlling the huge lateral movement of a gantry crane or a critical lifting movement of a container spreader, the correct choice of cables will make all the difference. Our spreader vertical reel cables are specifically designed to handle the intense gravity and torsion loads of vertical lifting, while our MV (medium voltage) reeling cables provide the robust power transmission needed for long-distance horizontal applications. To optimize your equipment's performance and longevity, consult with our technical teamfor customized reeling solutions.
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about HEBEI- HUATONG
Founded in 1993, Hebei-Huatong is a global cable manufacturing enterprise with production facilities located in Tangshan (Hebei Province, China), Busan (South Korea), Panama, Kazakhstan, Tanzania, Cameroon, and Angola. Its core product portfolio includes submersible pump cables for oil extraction, flexible moving cables for harbor cranes, cUL/CSA listed cables for AI PDU and marine shipboard cables. The company provides robust support for the continuous, safe, and efficient operation of industrial sectors worldwide, including offshore and onshore oil & gas exploration, and material handling via port cranes.
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