BASKET SPREADER 730
Spreader Bar Cable Application: What is a spreader bar? Container crane context: Gantry crane positioned at dock Overhead hoist mechanism: Winch + trolley system Spreader bar: Attachment point below hoist Function: Grips container corners, distributes load, tilts container for placement Spreader bar structure: Framework: Steel tubes/beams forming rectangular frame Lifting points: 4 corner attachment rings (one per container corner) Electrical system: Motor-driven locks, position sensors, lighting Cables: Power supply for motors + control signals for locking mechanism Cable location (spreader bar): Vertical run (primary): From crane hoist (top) down 20–40 m to spreader bar (bottom) Function: Supply power for: – Corner lock solenoids (release container locks) – Position feedback sensors (confirm locks engaged) – Optional: Spreader bar lighting (visibility during operation) Simultaneous function: Act as partial mechanical support (share load with main hoist cable) Horizontal distribution (on spreader bar): From entry point distributed across spreader frame Supply all four corner lock motors Branching: May split into smaller branches (4× circuits to corners) Mechanical load: Cable must withstand: Static tension: Weight of container payload (20–40 tons distributed) Dynamic loads: Jerking during load acceleration, swinging in wind Thermal: Tropical port environment, direct sun, saltwater spray Abrasion: Rubbing against spreader frame during operation Cable design philosophy: Dual function (unique): Electrical function: Deliver 300/500V power for locking system Mechanical function: Share load-bearing (not primary structure, but support role) Different from: Pure electrical cables (festoon, lifting): Electrical function only Pure mechanical ropes: Mechanical function only BASKET SPREADER 730: Both functions integrated Speed specification rationale: 160 m/min (relatively slow): Container crane cycle time: ~45–60 seconds per lift Descent distance: 20–40 m Descent speed: 20–40 m ÷ 45–60 sec = 0.33–0.9 m/s = 20–54 m/min Average speed: ~30 m/min (loading) + 20 m/min (discharge) = 25 m/min 160 m/min specification: 6–8× safety margin on speed Design: Allows for fast emergency ascent if needed Why not higher speed? Mechanical load constraint: Heavy cable (4000 N = ~400 kg equivalent) Inertia: Accelerating 400 kg + spreader bar + container inertia takes time Structural: Crane frame limits acceleration rates (safety interlocks) Result: 160 m/min is practical maximum for loaded spreader bar
