Types of Port Crane Brakes by Application

Braking systems in port cranes are divided into different categories based on the function they perform:

Service Brakes

These brakes are mounted on the high-speed shaft of the gearbox and are responsible for speed control and smooth load stopping under normal operating conditions. Service brakes are typically matched to the motor rating and allow automatic compensation for lining wear to maintain constant torque throughout the equipment's lifespan. Hydraulic options for these brakes offer unmatched torque stability and are widely used in high-torque applications such as ports and steel industries.

Emergency Brakes

Emergency brakes are mounted directly on the drum flange and serve as the last line of defense against load dropping. These brakes are activated in conditions such as overspeed detection, power failure, mechanical failure in the transmission system, or emergency stop by the operator. These systems are designed to perform reliably even in harsh industrial environments.

Parking and Storm Brakes

Due to the exposure of port cranes to open environments and strong winds, storm brakes are of particular importance. These brakes, typically of the wedge or wheel type, are designed as normally-closed and automatically engage upon power failure to prevent equipment from sliding in strong winds. The YFX-710/80 wedge brake is an example of this type, which uses a wedge mechanism to amplify spring force and provide high braking torque in a compact size.

Technical Classification of Brakes by Operating Mechanism

Drum Brakes

Drum brakes are among the oldest and most common types of brakes in lifting equipment. In this system, brake linings are pressed against the outer surface of a drum by spring force, and the resulting friction causes stopping. Electromechanical drum brakes are typically designed with wheel diameters of 8 inches and above, and their linings are made from non-asbestos materials.

Disc Brakes

Disc brakes are gradually replacing traditional drum brakes due to their higher precision and better controllability. The dual-caliper design in these brakes ensures balanced load distribution and reduces the risk of shaft twisting. RINGSPANN's DX series electrohydraulic disc brakes are designed for high replacement frequency and are used in emergency stop systems of port cranes.

Wheel Brakes

Wheel brakes act directly on the crane's travel wheels and use friction between the lining and the wheel tread for stopping. These brakes operate as independent brakes or in combination with motor brakes. It is recommended that at least 75% of gantry wheels be equipped with motor brakes or wheel brakes to ensure adequate braking capacity. The YLZ series hydraulic wheel brakes and DLZ63 series electric wheel brakes are examples of this category, designed as normally-closed and automatically engaging upon power failure.

Rail Brakes

Rail brakes create additional friction by applying force to the rail surface through grooved pads. These brakes assist in stopping the crane during emergency conditions, but a major drawback is that when activated, they remove load from the gantry wheels and reduce the braking friction of the drive wheels. Additionally, the grooved pads may become smooth due to wear and lose their friction capacity.

Technical Challenges and Design Considerations

Slipping and Skidding Issue

One of the main challenges in port crane braking is the phenomenon of slipping. The sliding friction of drive wheels in contact with a rail that is often wet or even greasy limits braking capacity. Experience has shown that sudden wind gusts can cause a working crane to skid, even when 50% of the wheels are braked. This issue underscores the importance of using storm brakes and additional control systems.

Torque and Braking Capacity

Military and industrial standards have defined specific requirements for braking capacity. According to MIL-HDBK-1038, mechanical brakes must be adjustable down to 50% of their rated torque by reducing spring tension. Hoist brakes must provide at least 130% of the motor's rated torque, while travel and slew brakes require 100% of the rated torque.

Adaptive Braking Systems

Modern braking technologies have moved toward adaptive systems that can adjust braking force based on load and speed conditions. RINGSPANN has developed an adaptive braking system consisting of three components: a control unit for selecting different valve configurations, a hydraulic power unit for controlling the application time of each emergency brake, and multiple brakes on the drum that enable different torques. This system prevents harmful torque peaks in the gearbox and steel structure.

Auxiliary Systems and Integration

Hydraulic Power Units

Hydraulic braking systems require specialized power units that provide the necessary force to activate emergency brakes. These units utilize redundant return valves for fast and safe operation, a hand pump for manual release during power failure, and a closed-loop system without external piping. Precise control of brake opening and closing times is ensured through these units.

Monitoring and Fault Detection Systems

Standards require that caliper disc brake systems for hoist rope drums be equipped with a fault detection system that activates the disc brake mechanism if there is a 5% change in the ratio of drum shaft speed to motor shaft speed. This real-time monitoring capability significantly enhances operational safety.

IIoT Capabilities

With the advancement of industrial technologies, modern braking systems are equipped with IIoT (Industrial Internet of Things) capabilities that enable monitoring of brake conditions, detection of lining wear, and planning of preventive maintenance. These capabilities contribute significantly to reducing unplanned downtime and increasing operational efficiency.

Specific Applications in Port Cranes

Hoist Brakes

Port crane hoists require multi-layer braking systems. On the high-speed side of the gearbox, service brakes of the disc or drum type are installed, while on the low-speed side, caliper disc brakes are used for emergency braking and preventing load dropping in case of shaft or transmission system failure. According to standards, if a caliper disc brake system is present on the hoist rope drum, only one electromechanical brake rated at least 150% of the motor's rated torque is required.

Gantry Travel Brakes

Longitudinal travel of the gantry crane along the quay requires strong and reliable braking systems. The mass of port container cranes ranges from 600 to 1000 tons, and stopping this massive mass at operating speeds requires precise brake system design. Wheel and rail brakes play a key role in these applications.

Slew and Boom Brakes

The crane slew mechanism as well as movable booms require controlled brakes to prevent oscillation and impact. Adaptive braking systems for booms can adjust braking force based on boom angle and prevent harmful stresses in the structure.

Environmental Considerations and Maintenance

Non-asbestos brake linings have become mandatory in all modern applications. These linings are made from wear-resistant materials that reduce environmental impact while maintaining braking performance. Access to standard spare parts and the availability of automatic monitoring systems optimize maintenance costs.