Modern hydraulic systems represent highly integrated, large-scale, complex mechatronic control systems. Hydraulic technology has been closely integrated with emerging technologies such as computer control, microelectronics, and sensor technology, evolving into an automated technology encompassing transmission, control, and detection. Mastering the principles of new hydraulic technologies and ensuring proper management and maintenance of hydraulic equipment are crucial for guaranteeing the safe and normal operation of port handling equipment.
Hydraulic System Applications in Equipment
Multifunctional Hook Block & Tilting Device
(1)Hook Block
The four lifting wire ropes on the hook block pass over pulleys at the piston rod ends of the hydraulic cylinders and are secured to the pressure plate on the front beam. The other ends are fixed to the drum. When the hydraulic cylinder piston is in the center position, all four lifting ropes are of equal length, maintaining the “neutral position.” When both pistons move simultaneously in the same direction—lifting the left side and lowering the right side—the lifting device tilts ‘rightward’; the opposite action tilts it “leftward.” If the piston connected to the front wire rope extends to the pulley while the piston connected to the rear wire rope retracts to the pulley, the front side of the lifting device is raised and the rear side is lowered, resulting in a “forward tilt”; the opposite action produces a “rearward tilt”.
(2) Cabin Snag Protection
Should a sudden cabin snag occur during the lifting device’s ascent from the cabin, severe damage to the hoisting mechanism and overall structure would result. However, the cabin snag protection hydraulic system effectively safeguards the gantry crane’s safety. The single cabin snag protection hydraulic system operates as follows:
During normal operation, all four piston rods are fully extended and under pressure. An integrated valve assembly is installed at the inlet and outlet ports of the rodless chamber of the cylinder. The main spool of the safety valve is a cartridge valve controlled by a pilot valve.
Upon hooking, when the pressure in one or more of the four cylinders reaches the preset value, the pressure switch immediately sends a signal to command the main hoisting motor to emergency stop. Simultaneously, the safety valve spills over, rapidly retracting the piston rods. The cylinder stroke ensures a “soft landing” for the hoisting mechanism before the motor stops. The entire process from cabin suspension to hoist stoppage is completed within 0.5 to 0.8 seconds, providing the entire machine with excellent safety protection.
Should internal leakage in any cylinder cause the piston rod to slip downward, the limit switch will emit a “slip” signal, commanding the oil pump to start and replenish oil to the system until all cylinders return to their “normal” operating positions. After resolving the cabin suspension fault, the operator need only press the ‘Reset’ button for the system to return to “normal” status.
(3) Lifting Device Horizontal Rotation
The distance between the front and rear pulleys of the hoisting wire rope on the trolley is greater than that between the front and rear pulleys on the lifting device. This creates a triangular angle between the front and rear wires on the lifting device, with each wire exerting a forward or backward component force. If the piston rods of cylinders A and B extend by a certain displacement, tightening the A and B corners of the spreader, while cylinders C and D retract by the same displacement, loosening the C and D corners, the spreader will rotate clockwise. Conversely, it will rotate counterclockwise. The maximum rotation angle is ±3°. Solenoid valves control the direction of movement for each of the four cylinders, while flow control valves synchronize the speed of their reciprocating motion.
Operating Principle of Gantry Crane Spreader
All spreader operations are hydraulically driven. The hydraulic system primarily consists of the pump source system, double-box lateral translation system, 20′-45′ telescoping system, guide plate system, pivot pin system, and intermediate lifting system.
(1) Pump Source System. Utilizes the PVP33 constant-power plunger pump from Parker (USA), capable of delivering full-power flow at two pressure levels to meet cylinder and hydraulic motor speed requirements. This pump also functions as a constant-pressure variable-displacement pump—delivering full displacement at low pressure and zero displacement at high pressure—reducing system heat generation and power consumption.
(2) Dual-Chamber Translation System. This system primarily comprises hook-head cylinders and dual-chamber translation cylinders, executing hooking and translational movements respectively. When transitioning from single-chamber to dual-chamber telescoping mode, the hook-head cylinders first connect the outer extension beam to the intermediate translation frame via the hooking action. The two hook-head cylinders are controlled by solenoid valves and hydraulically controlled check valves, with the latter primarily ensuring reliable locking of the hook-head cylinder positions. Each hook-head cylinder is equipped with two high-pressure inductive proximity switches that detect cylinder position by sensing piston movement.
(3) 20′-45′ Telescoping System. When the lifting device operates in single-box mode, solenoid valve 110 controls a high-torque PARKER cycloidal hydraulic motor for forward/reverse rotation, enabling the device’s 20′-40′-45′-40′-20′ telescoping motion.
(4) Guide plate system. Hydraulic motors drive guide plate movement. Each guide plate set incorporates a throttle valve to individually adjust the speed of the four guide plate sets for synchronized operation. Additionally, each swing cylinder is protected by a relief valve to prevent damage from guide plate impact.
(5) Pin rotation system. End pin rotation cylinders and intermediate pin rotation cylinders drive the opening and locking actions of the pins.
(6) Intermediate Lifting System. Four intermediate lifting cylinders drive the intermediate pivot box and intermediate pivot mechanism for vertical movement, enabling conversion between single-box and double-box telescoping modes.
Typical Hydraulic System Failures in Port Equipment
(1) Fault Symptom: Poor braking performance when vehicle speed exceeds 10 mph.
Fault Cause Analysis:
The Kalmar empty container stacker’s foot brake system employs a wet disc braking system: hydraulic pressure from the master brake valve actuates the brake piston within the service brake, clamping the brake pads to stop the wheels. Analysis of the foot brake system’s operating principle indicates the following potential causes:
(1) Malfunctioning master brake valve resulting in insufficient hydraulic pressure;
(2) Damaged brake accumulator unable to sustain adequate hydraulic pressure;
(3) Worn brake friction pads resulting in insufficient braking force;
(4) Damaged brake piston seals failing to maintain sufficient hydraulic pressure for pad compression.
Troubleshooting Process:
First, a brake pressure test was conducted on the master brake valve, yielding normal results. Subsequently, the accumulator was inspected and replaced, yet the fault persisted. Finally, the service brake assembly was disassembled for inspection. The brake pads were found normal, but the brake piston O-ring was damaged. After replacement, the fault was resolved.
(2) Fault Symptom: Both sides of the lifting device lock automatically in sequence while stationary.
Fault Cause Analysis:
The lifting device’s locking mechanism operates by the driver’s control lever opening the servo oil circuit via the lock solenoid valve. This servo circuit then activates the rotary lock control valve to open the main oil circuit, driving the lock cylinder to engage or disengage the locking pins. Based on the symptom—one side locking automatically first—the primary cause is likely internal leakage within the lock cylinder itself.
Troubleshooting Process:
The lock cylinder on the side that automatically locked first was disassembled for inspection. A damaged piston oil seal was found. After replacing the repair kit, the hoist operated normally during testing. However, the fault recurred after one work shift. Upon disassembling and inspecting the lock cylinder again, the oil seal was found intact, but the cylinder bore showed severe wear. Replacing the entire lock cylinder assembly resolved the issue.
(3) Fault Symptom: Slow lifting speed of the lifting device.
Fault Cause Analysis:
The lifting device operates by the driver controlling the lifting solenoid valve via the cab handle to open the servo oil circuit. This servo circuit then controls the lifting control valve to open the main oil circuit, activating the lifting cylinder to raise or lower the device. Analysis of the lifting mechanism indicates possible causes: (1) Faulty main supply pump causing insufficient main oil pressure; (2) Seized lift control valve spool restricting hydraulic flow; (3) Malfunctioning lift solenoid valve preventing servo circuit activation; (4) Defective main pressure relief valve causing inadequate main line pressure; (5) Faulty lifting cylinder.
Troubleshooting Process:
Initially, low main oil pressure was detected. After replacing the main supply pump, the fault recurred within two days. Inspection confirmed normal operation of the lifting solenoid valve and control spool. Removal of the main pressure relief valve revealed a stuck spool with fine metal debris attached. The spool was cleaned. Inspection of the removed hydraulic filter revealed a damaged element. Replacing the filter, cleaning the hydraulic tank and oil lines resolved the fault.
GBM Hydraulic Drive Enhancing Operation Efficiency
As the core drive and control unit of modern port handling equipment, the performance and reliability of hydraulic systems directly determine the overall operational efficiency and stability of the equipment. Leveraging mature hydraulic technology and extensive port equipment manufacturing experience, GBM is committed to developing and producing high-performance, low-failure-rate hydraulic drive lifting gear, providing robust and reliable execution assurance for critical port machinery such as quay cranes and yard cranes.
In hydraulic system design and component selection, GBM strictly adheres to high compatibility and durability standards. The system incorporates internationally renowned brands such as PARKER for hydraulic pumps, control valves, and actuators. It features excellent pressure-flow adaptive capabilities and power control characteristics, effectively reducing system heat generation and energy loss while enhancing overall equipment efficiency. To address the diverse and complex motion requirements of the lifting device, GBM’s hydraulic system integrates multiple independent control circuits. Each circuit manages distinct functions such as telescoping, lateral movement, guide plate operation, pivot pin rotation, and tilt. All circuits are equipped with precision regulating valves and safety protection devices, ensuring rapid response, high synchronization accuracy, and effective prevention of overload impacts.
To withstand the demanding, high-frequency port operating environment, GBM has implemented multiple reliability enhancements: high-pressure filter elements and fluid contamination control technology extend hydraulic component lifespan; key cylinders and motors incorporate built-in sensors for real-time monitoring of position, pressure, and temperature. Combined with PLC control systems, this enables predictive fault diagnosis and intelligent protection, significantly reducing unplanned downtime caused by hydraulic system failures.
The GBM hydraulically driven spreader not only comprehensively covers single-container, dual-container, and multi-condition loading/unloading requirements functionally, but also stands out as an ideal choice for enhancing port handling efficiency, ensuring operational continuity, and reducing overall operating costs. Its system efficiency, smooth operation, and maintenance convenience have proven outstanding in major port projects worldwide.
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