Container Spreader

Overview

A container spreader is the lifting attachment that hangs beneath a quay or yard crane and actually grips the shipping container. The crane provides the hoist; the spreader provides the intelligence and the grip, extending to match the box, dropping onto its four corner castings, and twisting four locks to make a positive mechanical connection rated to lift the loaded container. The unit described here is a telescopic spreader that adjusts between 20, 40, and 45 ft ISO containers and lifts up to 50 tonnes under its twistlocks.

The load path runs from the container, through the four corner locks, into the Telescopic Beam, up through the Head Block and into the crane's wire ropes. Powered functions are fed by the Power Pack and sequenced by the Control Box, which reports status up the cable to the crane cab.

How it works

The structure is the Telescopic Beam: a fixed center box with two telescoping end beams that slide on wear pads, extended and retracted by Telescope Actuator ball-screw drives to set the spread to the container length. Each end beam carries two Twistlock Corner assemblies. When the spreader lands, a spring Landing Pin at each corner depresses to confirm seating, then a Rotate Actuator turns the Twistlock ninety degrees inside the corner casting to lock it; lock sensors confirm all four have turned before the crane is allowed to hoist.

Aligning the spreader onto a container is the job of the four Guide Flipper guides, pivoting arms driven down by hydraulic Flipper Cylinder rams to funnel the box into the corners. The hydraulics come from the Power Pack, where an electric Pump Motor pressurizes oil and a relay-switched Valve Bank directs it to each function.

The whole sequence of telescoping, landing, locking, and flipping is run by the Control Box, an MCU that takes commands from the crane operator and feeds back lock, landing, and size status gathered by the Sensor Pack. Corner Floodlight units in the Work Lights illuminate the work for night moves.