Introduction
Quay cranes, commonly referred to as shore cranes, are specialized machinery used at container terminals for loading and unloading containers from ships and vehicles. Container spreaders are indispensable for the operation of these cranes. The use of container spreaders maximizes the performance of quay cranes, enhances the quality and efficiency of container handling operations, and improves port economic efficiency. Therefore, research on container spreaders holds significant importance.
Definition and Types of Container Spreaders
The national standard for container spreaders (GB/T3220-2011) defines them as: “A container spreader is a lifting tool that connects to cranes and lifting equipment to perform hoisting operations. It features a structure compatible with container bodies and connects to the corner fittings of a container via a corner pin (rotating lock) located at the spreader’s corner to perform container lifting operations .”
The national standard for container spreaders (GB/T3220-2011) defines a container spreader as: a lifting device that facilitates the hoisting and lowering of containers via cranes and lifting equipment. It possesses a structure compatible with the container body and can connect to the container’s corner fittings through swivel (rotating) locks located at the corners of the spreader to perform container lifting operations.
Fixed container spreaders lack dedicated telescoping mechanisms, maintaining constant geometric dimensions. Primary types include 10ft, 20ft, 30ft, 40ft, and 45ft spreaders. Key characteristics: simple structure, easy manufacturing, lightweight, and low cost. These spreaders handle only one container length specification.
Telescopic container spreaders incorporate an extension mechanism, allowing length adjustment between 6.1m (20ft) and greater lengths. They can handle containers of varying dimensions. Key characteristics include a more complex structure and heavier weight. However, their adaptability and ease of length adjustment significantly enhance loading/unloading efficiency, making them widely adopted.
Telescopic Container Spreader
The telescopic container spreader primarily consists of the spreader’s metal structure, working mechanism, drive system, and control system.
Lifting Device Metal Structure
The metal steel structure functions to bear and transmit loads while mounting the working mechanism, drive unit, and electrical control system.
It primarily consists of an upper frame, main beam, and telescopic beams, forming a fully enclosed frame structure. Sheaves are arranged at the four corners of the upper frame, directly suspended from the lifting wire rope. The upper frame connects to the main beam via pins. A tilt mechanism is typically positioned between the main beam and the upper frame. The main beam houses the drive units for the working mechanisms, the control system, and cable storage devices. The telescopic beam structure is nested within the main beam, enabling it to extend and retract within the main beam under the force of the telescopic drive. This metal structure for container spreaders offers high strength and rigidity with low self-weight, making it widely applicable.
Lifting Device Working Mechanisms
Container lifting devices are generally equipped with working mechanisms including a twist-lock mechanism, telescopic mechanism, guidance mechanism, and tilt mechanism. Their function is to enable the connection or disconnection of the lifting device with the container, adjust the length of the lifting device, rapidly guide the device to align with the container, and adjust the tilt movement of the lifting device through the actions of each working mechanism. This satisfies the requirements for container loading and unloading operations under different working conditions.
(1) Twist Locking Mechanism
The twist locking mechanism connects the spreader to the container during loading/unloading and disconnects them afterward. For standard container spreaders, this mechanism primarily consists of spreader swivels and container corner fittings, as shown in Figure 2. Spreader swivels are mounted at the four corners of the spreader’s telescopic beam frame.
When the spreader descends onto the container via the guide mechanism, the spreader locks engage into the lock holes above the container corner fittings and rotate 90°. Once all spreader locks secure the container, loading/unloading operations can commence. After the container is positioned, rotating all spreader locks another 90° allows separation from the container. The driving force for the lifting device’s swivel locks is typically provided by hydraulic cylinders for hydraulic lifting devices and electric motors for electric lifting devices.
(2) Telescoping Mechanism
The telescoping mechanism drives the extension/retraction of the lifting device’s telescopic frame, altering its length to handle containers of varying dimensions. The time required for length adjustment is generally specified to be less than 30 seconds. The minimum telescoping length is 20ft, with maximum lengths of 40ft or 45ft.
Telescoping mechanisms are primarily categorized by drive type: hydraulic cylinder drive, chain drive, or combined hydraulic cylinder and chain drive.
The telescoping mechanism also incorporates limit devices, buffers, and safety protection devices. Limit devices restrict the working position during movement, ensuring precise telescoping positioning. Buffer devices absorb part of the impact energy during extension/retraction. Overload protection devices prevent excessive loading on the lifting device’s telescoping mechanism, safeguarding its transmission components from damage.
(3) Guidance Plate Mechanism
The guidance mechanism directs and positions the container lifting device as it approaches the container, enabling rapid container alignment and enhancing loading/unloading efficiency. Guidance mechanisms are categorized into fixed and movable types based on whether they can move during operation. Fixed guidance mechanisms typically secure guide plates to the main beam or telescopic beam with bolts. Some are positioned at the four corners of the telescopic beam frame, while others are arranged on the sides of the main beam or telescopic beam frame.
Movable guide mechanisms feature guide plates capable of vertical flipping motion, typically mounted at the four corners of the reach stacker’s telescopic beam frame. Guide plates may flip individually, in pairs, or simultaneously. During container alignment, the plates flip downward to engage the container’s four corners; conversely, they flip upward during disengagement.
The movable guide mechanism generally consists of guide plates and a guide plate drive unit. The ends of the guide plates are typically tapered or angularly tapered. The guide plate drive unit primarily employs two forms: reciprocating hydraulic cylinders and swing hydraulic cylinders.
(4) Tilting Mechanism
The tilting motion of the lifting device refers to its ability to perform three movements: forward/backward tilt, left/right tilt, and planar rotation. The function of the lifting device tilt mechanism is to adjust the tilt movement to meet the rapid loading/unloading requirements of containers under various working conditions. Typically, the tilt range is ±5° for fore/aft tilt, ±(3~4°) for lateral tilt, and ±5° for planar rotation.
Lifting Equipment Drive System
The lifting device drive system activates the working mechanisms to perform corresponding actions. Common types include hydraulic drive and electric drive. Electric drive systems feature simple structure, easy control operation, and convenient maintenance, representing the future development direction.
Lifting Equipment Control System
The control system manages the lifting device’s movements, altering its motion characteristics. It controls functions such as lifting, lowering, moving, speed adjustment, direction change, and braking. Additionally, it regulates the operation of working mechanisms including rotation locking, telescoping, guidance, and tilting.
GBM Serve Port Operations With Superior Reliability
As a specialized supplier of port handling equipment, GBM is dedicated to developing and manufacturing high-performance gantry crane telescopic container spreaders. Its products have gained widespread adoption and trust at numerous global ports and terminals due to their sophisticated electrical and hydraulic system configurations, outstanding structural durability, and low failure rates.
A core strength of GBM telescopic spreaders lies in their critical components, which exclusively utilize high-quality products from renowned domestic and international brands. The electrical system employs control modules and sensors with high protection ratings, ensuring stable signal transmission and strong anti-interference capabilities. This guarantees precise and reliable command responses for spreader operations including telescoping, locking, and guide plate movements. The hydraulic system integrates high-performance constant-power pumps, precision control valves, and high-pressure-resistant cylinders. Its rational layout and superior sealing not only enable rapid, smooth telescoping for containers ranging from 20 to 45 feet but also effectively control internal leakage and system heat generation, thereby extending the entire hydraulic system’s service life.
In structural design and manufacturing, the GBM spreader body utilizes high-strength steel and advanced welding techniques. Critical load-bearing areas undergo reinforcement treatment, delivering outstanding fatigue and impact resistance. This design adapts to the high-intensity, high-cycle operational demands of port environments, significantly extending the overall service life of the spreader.
