Common Problems and Solutions for Tower Crane Slewing Mechanism

The tower crane slewing mechanism is a critical component in the efficient and safe operation of tower cranes. It enables the crane to rotate its jib and counter-jib, allowing for precise material handling across a wide radius. However, like any mechanical system, the slewing mechanism is susceptible to various problems that can disrupt operations and pose safety risks.
Understanding these common issues, their solutions, and proper maintenance practices is essential for ensuring the reliable and long-lasting performance of tower cranes.

Main Components of Tower Crane Slewing Mechanism

The slewing mechanism comprises several essential components that work in tandem to facilitate smooth and controlled rotation.

Slewing Bearing

This large-diameter bearing is the heart of the slewing mechanism, connecting the rotating superstructure to the stationary tower. It must withstand significant axial, radial, and moment loads. Typically, it features a large gear ring for driving the rotation.

Slewing Drive Unit

This unit consists of an electric motor, a gearbox (reducer), and a brake. The motor provides the rotational force, which is then reduced and amplified by the gearbox to achieve the necessary torque. The brake ensures precise stopping and holding of the rotating parts.

Slewing Gear

The slewing gear, integrated with the slewing bearing, meshes with the output gear of the slewing drive unit. This gear transmission system transmits the rotational force from the drive unit to the slewing bearing, enabling the crane to rotate.

Control System

The control system manages the operation of the slewing mechanism. It includes electrical components, sensors, and control software that regulate the speed, direction, and braking of the rotation. Safety features, such as overload protection and limit switches, are also integrated into the control system.

Metal Structure

This includes the slewing platform, and any structural steel that supports the slewing bearing, and drive unit. The structural integrity of these parts is vital for the stability and safety of the crane during slewing operations.

Common Problems and Solutions for Tower Crane Slewing Mechanism

The slewing mechanism of a tower crane is crucial for horizontal movement. The following table shows some common faults, causes and troubleshooting methods：

Number	Tower Crane Slewing Mechanism Fault	Cause of Tower Crane Slewing Mechanism Fault	How to Troubleshoot
1	Slewing speed cannot be increased	1. External power supply voltage too low 2. Brake cannot fully open 3. Speed potentiometer failure 4. Speed controller failure	1. Check external power supply 2. Check brake circuit 3. Repair or replace 4. Replace
2	Slewing cannot be braked	1. Slewing speed not reduced to a certain level 2. KHS failure 3. Speed controller failure	1. Wait for speed to decrease 2. Repair or replace 3. Replace
3	Abnormal noise during slewing	1. Lack of lubrication 2. Loose connecting bolts 3. Loose process hole plugs	1. Add oil 2. Tighten 3. Repair
4	Slewing cannot turn left	1. Turned to left limit 2. Left linkage to PLC signal line open circuit	1. Turn right one revolution 2. Repair or replace
5	Excessive impact noise during slewing speed change	Loose or damaged connecting bolts	Tighten or replace
6	Slewing stops, reducer still twists	Loose connecting bolts	Tighten or replace
7	Slow speed and motor overheating at low slewing speed	1. Excessive eddy current 2. Three-phase power imbalance	Repair
8	Unstable slewing, inaccurate positioning	Eddy current braking voltage too low	Adjust to normal value
9	Slewing cannot be limited	Slewing limit switch failure	Repair or replace

Maintenance of Tower Crane Slewing Mechanism

To prevent the tower crane slewing operation from stopping, it is necessary to perform daily inspections and repairs. Regularly check the operation of components such as the tower crane slewing motor, brakes, and gearboxes to identify and resolve faults in a timely manner. Additionally, when operating the tower crane, strictly adhere to the instructions in the manual to avoid excessive loads or prolonged operation that could lead to overheating and damage, thereby posing safety hazards to the tower crane.

Regular Inspection and Lubricant Replacement

Regularly inspect the slewing bearing, drive unit, and gears for wear, damage, and proper lubrication. Follow the manufacturer’s recommendations for lubricant type and intervals.

Inspection of Fasteners

Regularly check and tighten all bolts and fasteners to the specified torque to prevent loosening.

Prevention of Abnormal Noise and Wear

Monitor the slewing mechanism for any unusual noises or vibrations, which can indicate potential problems. Investigate and address these issues promptly.

Cleaning and Maintenance

Keep the slewing mechanism clean and free from debris. Regularly clean and inspect all components.

Prevention of Damage During Long Periods of Inactivity

If the crane is not in use for an extended period, protect the slewing mechanism from environmental factors. Rotate the mechanism periodically to ensure proper lubrication and prevent seizing.

CPTC – Your Tower Crane Slewing Mechanism Provider

Choosing a reliable provider for tower crane slewing mechanisms is essential for ensuring quality, performance, and support. CPTC, as a dedicated provider, offers:

• High-quality slewing bearings, drive units, and gears.
• Expert technical support and maintenance services.
• Prompt delivery and availability of spare parts.
• Comprehensive training and guidance for operators and maintenance personnel.

By partnering with a trusted provider like CPTC, tower crane operators can ensure the longevity and reliability of their slewing mechanisms, minimizing downtime and maximizing productivity.

In conclusion, the tower crane slewing mechanism is a vital component that requires careful attention and maintenance. By understanding the common problems, implementing effective solutions, and adhering to regular maintenance practices, operators can ensure safe and efficient crane operations.

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