Crawler cranes rely on a complex system of crane parts to deliver stability, mobility, and lifting power. Unlike wheeled cranes, they use tracks instead of tires, requiring specialized components for terrain adaptation, weight distribution, and lifting efficiency. Below is a detailed guide to the essential crane parts of a crawler crane, their positions, functions, and why they matter.
1. Undercarriage– The Foundation of Stability
The undercarriage is the base structure that supports the crane’s weight and enables movement. It includes:
A. Tracks
Position: Wraps around the sprockets, idlers, and rollers, forming a continuous loop.
Function: Provides traction, stability, and weight distribution on soft/uneven terrain.
Key Crane Parts Inside Tracks:
Track Shoes – Outermost wear parts that contact the ground. Made of high-strength alloy (e.g., 28CrMnMo, 31Mn2SiMoNi) for durability.
Track Links – Connects track shoes into a loop; reinforced with pins & bushings.
The boom and lifting system of a crawler crane is a sophisticated assembly of components that work in harmony to perform the core function of the crane – lifting heavy loads with precision and safety. While these parts are not part of the track system that provides mobility, they are absolutely critical for the crane’s lifting operations.
A. Main Boom
Position
The main boom is the most prominent and essential part of the lifting system. It is designed to extend both vertically and horizontally. Vertically, it can be raised to great heights to reach elevated work areas, such as when lifting materials to the upper floors of a building under construction. Horizontally, it can be positioned at various angles to place the load precisely at the desired location. The main boom is typically mounted on the slewing platform of the crawler crane, allowing it to rotate 360 degrees, which further enhances its operational flexibility.
Function
Telescopic Main Boom
Structure: Consists of multiple sections that can be extended or retracted, similar to a telescope.
Advantages: Allows for relatively compact storage when not in use and enables quick adjustment of the working length on-site.
Lattice-Type Main Boom
Structure: Made up of a framework of interconnected beams, usually in a triangular or truss-like pattern.
Advantages: Gives it a high strength-to-weight ratio, making it suitable for very heavy-duty lifting operations. It is often more stable at greater lengths.
Disadvantages: May be less convenient to set up and transport compared to the telescopic boom.
B.Jib
Position
The jib is an auxiliary component that is attached to the main boom. It extends out from the end of the main boom, effectively increasing the overall reach of the crane. The jib can be fixed at a specific angle or, in some cases, be adjustable to fine-tune the position of the load.
Function
The main function of the jib is to increase the lifting height and reach of the crane. By adding the jib to the main boom, the crane can access areas that would otherwise be out of reach. For example, when constructing a tall tower or a bridge, the jib allows the crane to lift materials to the uppermost levels.
However, it is important to note that while the jib increases the reach, it also reduces the maximum load capacity of the crane. This is because the jib adds a lever arm, which increases the bending moment on the main boom and the crane’s structure.
Therefore, when using a jib, the crane operator must carefully calculate the allowable load based on the length of the jib and the angle at which it is set.
C. Hoist Winch
Position
The hoist winch is mounted on the slewing platform of the crawler crane. It is directly connected to the hook via a wire rope. The slewing platform allows the hoist winch and the entire lifting system to rotate along with the rest of the crane’s upper structure, providing 360-degree coverage for lifting operations.
Function
The hoist winch is the power-driven component responsible for winding and unwinding the wire rope. When the winch winds the wire rope, it pulls the load upwards, lifting it off the ground or from a lower position. Conversely, when the winch unwinds the wire rope, it allows the load to be lowered gently to the desired location.
D.Hook Block
Position
The hook block is located at the end of the wire rope, right above the lifting hook. It is a compact but crucial component of the lifting system.
Function
The hook block serves two main functions.
Even Load Distribution
Firstly, it distributes the load evenly across the wire rope. By using a system of pulleys within the hook block, the force exerted on each strand of the wire rope is balanced, reducing the risk of individual strands being overloaded and breaking.
Multi-Pulley Lifting
Secondly, the hook block allows for multi-pulley lifting. Multi-pulley systems, also known as block and tackle systems, increase the mechanical advantage of the lifting operation. This means that a smaller force applied to the wire rope can lift a much heavier load.
3. Cab & Controls
A. Operator Cab
Position: Elevated for visibility, often rotating with the slewing ring.
Function: Houses controls for lifting, movement, and safety systems.
B. Slewing Ring
Position: Connects the upper structure to the undercarriage.
Function: Enables 360° crane rotation for precise positioning.
