Introduction: One Cable, Three Transport Systems

Port crane cable management is not a one-size-fits-all engineering problem. Different crane types, travel distances, operating speeds, and site conditions demand different cable transport architectures. A 200-metre STS crane boom may use a free-hanging curtain festoon. A 500-metre RTG crane runway may use motorised carrier drums. An enclosed overhead gantry in a dusty bulk terminal may use a cableveyor track system. Each architecture subjects the cable to a distinct combination of mechanical stresses—catenary tension, drum winding compression, guided track bending—and each demands a cable specifically engineered to survive those stresses for millions of operational cycles.

The 600V 2TC-RB is the TRACAB® product line cable designed to perform reliably across all three transport methods: curtain (festoon), carrier drum (reeling), and cableveyor (enclosed track). Manufactured to JIS C 3327 Class 2, this cable combines the proven EP rubber insulation and polychloroprene rubber sheathing platform with Class 2 conductor construction optimised for the specific bending profiles and fatigue modes encountered in each transport architecture. The Kevlar® para-aramid fibre braided tensile reinforcement provides the mechanical backbone that enables a single cable design to absorb the dynamic loads generated by catenary suspension, drum winding, and track-guided travel without transferring stress to the conductors or insulation system.

The result is a universal crane cable that simplifies procurement (one cable type across multiple crane systems), reduces spare part inventory, and ensures consistent, proven performance regardless of which transport method is used—or if the transport method changes during the crane’s operational life due to modifications or upgrades.

Technical Specifications: JIS C 3327 Class 2

TRACAB® Transport Architecture: Curtain, Carrier Drum & Cableveyor

Curtain (Festoon) System

In a curtain system, the cable hangs in free catenary loops between trolley-mounted carrier saddles suspended from an overhead rail. As the crane trolley travels, the cable loops gather and spread—resembling a sliding curtain. The cable must support its own weight in the catenary span, absorb dynamic acceleration and deceleration forces from trolley movement, and withstand millions of gathering/spreading cycles. The primary stress mode is tensile loading combined with cyclic bending. The Kevlar® tensile reinforcement absorbs the self-weight catenary load and dynamic forces, while the EP rubber insulation and Class 2 conductor construction withstand the repeated bending at carrier saddle contact points.

Carrier Drum (Reeling) System

In a carrier drum system, the cable winds onto and unwinds from a motorised reeling drum as the crane travels. The drum is typically mounted on the crane structure, and the cable feeds from a fixed anchor point through a level-wind mechanism onto the rotating drum. The cable must withstand compressive winding forces (especially in multi-layer winding where upper layers press on lower layers), controlled tensile loading (from the cable’s weight plus the level-wind tension), and repeated bending at the drum surface radius. The 2TC-RB’s Class 2 construction is particularly advantageous here: the conductor stranding provides superior resistance to the compressive deformation experienced during tight drum winding, and the Kevlar® layer prevents cable elongation that would cause uneven drum packing.

Cableveyor (Enclosed Track) System

A cableveyor system guides the cable through an enclosed C-shaped or U-shaped track (also called an energy chain or cable track). The cable bends around the track’s fixed bend radius as the moving section of track travels relative to the fixed section. The cable must withstand guided bending at a fixed, known radius (typically 200–600 mm depending on track size), lateral guidance forces from contact with the track sidewalls, and surface abrasion from sliding contact with the track interior. The polychloroprene sheath’s excellent abrasion resistance is critical in this application, and the Kevlar® reinforcement prevents cable stretching that would cause slack accumulation and jamming within the track.

Class 2 Conductor Construction: The Flexibility Difference

The 2TC-RB is designated Class 2 per JIS C 3327 and IEC 60228, which specifies a stranded conductor with moderate flexibility. Class 2 conductors use fewer, thicker strands than Class 5 (very flexible) conductors, but more strands than Class 1 (solid) conductors. This intermediate construction is deliberately engineered for the specific mechanical demands of TRACAB® transport systems.

The Class 2 advantage lies in its balance between flexibility, compressive resistance, and tensile stability. In curtain (festoon) applications, Class 2 provides sufficient flexibility for the catenary bending cycles while offering greater resistance to permanent elongation under sustained tensile load than extremely fine-stranded Class 5 construction. In carrier drum (reeling) applications, Class 2’s thicker strands resist the compressive deformation that occurs when cable layers stack on the drum—fine-stranded Class 5 conductors can flatten and deform under multi-layer winding pressure, reducing cross-sectional area and increasing resistance. In cableveyor (track) applications, Class 2 provides the guided-bending flexibility required at fixed track radii while maintaining conductor geometry under the lateral forces from track sidewall contact.

The tin-coated annealed copper strand wire ensures that the Class 2 construction retains its mechanical properties throughout the cable’s service life. The annealing process eliminates work hardening from the wire drawing process, maximising ductility and preventing the gradual embrittlement that would cause strand breakage under repeated bending. The tin coating prevents inter-strand corrosion in the humid, salt-spray-laden port environment—corrosion between strands can effectively bond adjacent strands together, converting a multi-strand conductor into a quasi-solid conductor with dramatically reduced flexibility.

Cable Construction: Layer-by-Layer Engineering

The 2TC-RB cable comprises six functional zones, each engineered for the combined mechanical demands of curtain, carrier drum, and cableveyor transport:

Layer 1 — Conductor: Tin-coated annealed copper strand wire, Class 2 stranding. Strand configurations range from 50/0.18 (1.25 mm²) to 37/55/0.45 (325 mm²). The Class 2 stranding provides the balance of flexibility and compressive resistance required for multi-method transport compatibility.

Layer 2 — Separator: A thin separator tape wraps each conductor, preventing the EP rubber insulation from bonding to the copper surface. Free conductor movement within the insulation tube is essential for preventing insulation cracking during the repeated bending cycles in all three transport methods.

Layer 3 — EP Rubber Insulation: Ethylene propylene rubber provides the primary dielectric barrier. Insulation thickness ranges from 0.8 mm (small conductors) to 2.5 mm (large conductors). EP rubber’s superior flexibility retention at low temperatures (−30°C), ozone crack resistance, and ability to maintain dielectric strength after millions of flex cycles make it the ideal insulation for dynamic crane cables.

Layer 4 — Coloured Tape & Fillers: Each insulated core is wrapped with a coloured identification tape per the wire core identification scheme. In multi-core cables, non-hygroscopic fillers occupy the interstices between cores. A binder tape wraps the assembled core bundle.

Layer 5 — Kevlar® Aramid Braided Tensile Layer: The proprietary helical-braided aramid reinforcement layer provides the structural backbone. With tensile strength of approximately 3,620 MPa at 1.44 g/cm³ density, the Kevlar® braid absorbs catenary loads (curtain), winding tension (carrier drum), and track tension (cableveyor) while protecting internal cable components from mechanical stress.

Layer 6 — Polychloroprene Rubber Sheath: The outer protective sheath provides environmental defence against oil, UV, saltwater, abrasion, and flame. Sheath thickness ranges from 1.6 mm (small single-core) to 5.5 mm (4-core 200 mm²). The polychloroprene sheath’s abrasion resistance is particularly important for cableveyor applications.

Kevlar® Aramid Braided Tensile Reinforcement

The Kevlar® para-aramid fibre braided tensile reinforcement is the engineering feature that enables the 2TC-RB to function across all three TRACAB® transport methods. Without this reinforcement, the cable’s conductors would bear the full mechanical load—an untenable situation resulting in progressive conductor fatigue and premature failure.

In curtain (festoon) systems, the Kevlar® braid absorbs the catenary self-weight load and dynamic forces. A 4-core 200 mm² cable weighing 11,440 kg/km generates over 1,100 kg of self-weight tension in a 100-metre span—a load the Kevlar® braid handles effortlessly but that would stretch and fatigue bare copper conductors within weeks.

In carrier drum (reeling) systems, the Kevlar® braid maintains cable dimensional stability under winding compression. The aramid braid resists radial compression, preventing the cable from flattening and ensuring consistent unwinding behaviour throughout the drum’s layer capacity.

In cableveyor (track) systems, the Kevlar® braid prevents cable elongation under the track’s pulling forces. The aramid braid’s low elongation at break (~3.6%) limits cable stretch to negligible levels, maintaining proper cable tension throughout the track length and preventing slack accumulation that could cause jamming.

EP Rubber Insulation & Polychloroprene Sheath

EP Rubber Insulation provides dielectric strength of 20–30 kV/mm, giving a safety margin of 25–100× the 600V rating. EP rubber maintains flexibility at −30°C, resists ozone cracking, and withstands millions of flex cycles without micro-cracking. Minimum insulation resistance ranges from 200 MΩ·km to 500 MΩ·km at 20°C.

Polychloroprene Rubber Sheath provides simultaneous oil resistance, flame retardancy, UV stability, ozone resistance, saltwater impermeability, and abrasion resistance. For the 2TC-RB, the polychloroprene sheath’s abrasion resistance is a critical performance parameter for cableveyor track systems where the cable surface is in continuous sliding contact with the track interior. The material is inherently self-extinguishing—a safety requirement for crane cable trays.

Wire Core Identification & Tracer Method

For cables with 5 or more cores, the 2TC-RB uses the tracer method of core identification. The first three cores are identified by distinct colours (Black, White, Red), and all subsequent cores are Black with a coloured tracer stripe or tape to distinguish each core from the others. This method ensures clear, reliable core identification even in cables with 20 or 30 cores.

Dimensional & Electrical Data: Single Core (1.25–325 mm²)

Dimensional & Electrical Data: Multi-Core 2–4 Cores (1.25–200 mm²)

Dimensional & Electrical Data: Multi-Core 5–30 Cores (1.25–5.5 mm²)

Application Guide: Port Cranes & Material Handling Systems

STS Gantry Cranes — Curtain Festoon Systems

Super Post-Panamax STS cranes with 50–140 metre boom lengths are the primary curtain festoon application. The 2TC-RB cable hangs in catenary loops between trolley carriers. Cable selection: 3-core or 4-core 38–100 mm² for main hoist and trolley drives, 20–30 core 1.25–2 mm² for control and signalling. The Kevlar® reinforcement absorbs the substantial catenary loads generated by the heaviest cable sizes—a 4-core 200 mm² cable at 11,440 kg/km generates over 1 tonne of self-weight tension in a 100-metre span.

RTG Cranes — Carrier Drum Reeling Systems

Rubber-tyred gantry cranes in container yards use motorised carrier drums to manage the power cable as the crane travels 300–600 metres along container storage rows. The 2TC-RB’s Class 2 construction resists the compressive flattening that occurs during multi-layer drum winding, while the Kevlar® layer maintains consistent cable tension during unwinding. Typical selection: 3-core 22–60 mm² for main power supply.

Overhead Gantry Cranes — Cableveyor Track Systems

Indoor and outdoor overhead gantry cranes in bulk terminals, steel mills, and manufacturing facilities use cableveyor (energy chain) track systems. The enclosed track protects cables from environmental contamination while providing guided, controlled cable movement. The 2TC-RB’s polychloroprene sheath withstands continuous track contact abrasion, and the Class 2 conductor construction provides reliable performance at the track’s fixed bend radius.

Ship Unloaders — Mixed Transport Systems

Large ship unloaders often combine multiple transport methods: a curtain festoon for the trolley travel, a carrier drum for the gantry travel, and a cableveyor for the shuttle mechanism. The 2TC-RB’s TRACAB® compatibility across all three methods enables standardisation of the entire cable inventory for the unloader.

2TC-RB Class 2 vs. 2TC Light Class 3: Selecting the Right Class

Installation Best Practices for Each Transport Method

Curtain (Festoon) Installation

Size carrier trolley saddles for the cable’s maximum outer diameter with 10–15% clearance. Maintain the minimum dynamic bending radius of 6× OD at all guide points and end terminations. Festoon end clamps must include strain relief that transfers load to the Kevlar® braid rather than the conductors. Inspect carrier saddles every 6 months for wear.

Carrier Drum (Reeling) Installation

Drum diameter must be at least 12× the cable OD for power cables and 10× OD for control cables. Wind the cable under consistent tension (1–2% of rated breaking strength) using a level-wind mechanism. For multi-layer winding, verify the cable can withstand the cumulative compressive force of all planned layers—consult Feichun for layer-pressure calculations.

Cableveyor (Track) Installation

The track’s internal bend radius must meet or exceed 6× OD. Cable fill ratio within the track should not exceed 80% of internal cross-sectional area. Use separator bars between power and control cables. Verify polychloroprene sheath compatibility with track material (polychloroprene is compatible with standard nylon and UHMWPE track materials).

Universal Requirements

All power cable terminations should use crimped compression lugs with insulation boots. Control cable terminations should use industrial connectors with IP65 minimum protection. All termination points must include strain relief devices transferring load to the Kevlar® braid. Perform insulation resistance testing annually using a 500V megger.

Technical FAQ

What does “TRACAB” mean?

TRACAB® is a product line designation indicating that the cable has been specifically engineered and validated for use in three transport architectures: curtain (festoon), carrier drum (reeling), and cableveyor (enclosed track). The designation signifies that the cable’s construction has been optimised for the combined mechanical demands of all three systems.

Can the 2TC-RB be used with VFD-driven motors?

The 2TC-RB does not include an EMI shield. For VFD output cables, the shielded 2TC Light-SB (2PNCT-SB) variant should be used instead. The 2TC-RB is suitable for direct-on-line motor power, control circuits, lighting, and applications where VFD-generated EMI is not a concern.

Why does the 2TC-RB offer 5.5 mm² in the 5–30 core range while the 2TC Light only goes to 3.5 mm²?

The 2TC-RB’s TRACAB® target applications—large STS cranes, ship unloaders, and heavy material handling systems—often require higher-current control and auxiliary circuits. Motor brake circuits, heating elements, and high-power control relays on large cranes may require 5.5 mm² conductors in multi-core control cables.

What is the maximum carrier drum travel speed?

The cable is validated for carrier drum applications at travel speeds up to 250 m/min (4.2 m/s). Higher speeds may be possible depending on the specific cable size, drum diameter, and tension management system. Contact Feichun for high-speed reeling applications.

Is the 4-core 200 mm² cable practical for festoon systems?

The 4-core 200 mm² cable weighs 11,440 kg/km with 75 mm overall diameter. The Kevlar® reinforcement handles the self-weight load, but the festoon carrier system must be designed for this weight—requiring heavy-duty trolley frames, reinforced overhead rails, and shorter span lengths. For spans exceeding 15–20 metres, intermediate support carriers are essential. Carrier drum reeling is often more practical for the heaviest cable sizes.

How does the cable perform in extreme cold?

The 2TC-RB is rated for continuous operation at −30°C. For arctic port installations (−40°C and below), Feichun offers a special cold-climate formulation. Contact the engineering team for extreme cold specifications.