Jib Crane Extension Sections | Modular Boom Extenders

Product Specifications

Technical details and manufacturing context for Extension Sections

Definition

Extension sections are modular, structural components designed to be added to the main boom of a jib crane. Their primary role within the Jib Extension system is to increase the crane's horizontal working radius, allowing it to service a larger area from a fixed pivot point. They are typically bolted or pinned between the main boom and the jib head. These sections are passive structural members; they transmit the load from the jib head (where the hoist is attached) back to the main boom and ultimately to the crane's mast or wall bracket. Their design ensures structural integrity and minimal deflection under load across the extended reach. Extension sections are typically fabricated from high-strength steel, with material grades such as Q235B to Q355B (per GB/T 1591) depending on capacity and span requirements. Key parameters include rated capacity (1–5 t, per ISO 4301-1), extension length (1–3 m), boom cross-section (200×200 to 400×400 mm), and weight (150–500 kg). Surface treatment includes blast cleaning to Sa2.5 (ISO 8501-1) and paint thickness of 80–120 μm (ISO 19840). Operating temperature range is -20 to 60 °C. Dimensional tolerances on length are ±2 mm (ISO 2768-m), bolt hole diameter is 18–30 mm (ISO 273), and bolt hole spacing is 100–200 mm. Welds must meet ISO 5817 quality level, with full penetration (100%). These values are reference ranges; actual specifications must be verified with the legal manufacturer or supplier for the specific model and application. Extension sections are selected based on the required reach, load capacity, and compatibility with the existing boom. Proper installation and regular inspection are essential to maintain safety and performance.

Working Principle

Extension sections are passive structural members. They transmit the load from the jib head (where the hoist is attached) back to the main boom and ultimately to the crane's mast or wall bracket. Their design ensures structural integrity and minimal deflection under load across the extended reach. The sections are bolted or pinned to the main boom and jib head, creating a continuous load path. The cross-section and material grade are chosen to resist bending and shear forces while limiting deflection. The rated capacity decreases as extension length increases, so the load chart must be consulted. Proper torque on bolts and alignment of holes are critical for load transfer. Regular inspection for weld cracks, deformation, and corrosion is necessary. Failure to follow specified parameters can lead to structural failure.

Common Materials

High-strength steel

Technical Parameters

Parameter	Typical range	Notes & selection driver
Rated Capacity	1–5 t	Maximum load at the hook; exceeds this reduces safety margin.ISO 4301-1
Extension Length	1–3 m	Determines reach; longer sections reduce capacity.
Boom Cross-Section	200×200–400×400 mm	Matches existing boom; affects stiffness and weight.
Material Grade	Q235B–Q355B	Higher grade for higher capacity or longer spans.GB/T 1591
Surface Treatment	Sa2.5	Blast cleaning before painting; ensures adhesion.ISO 8501-1
Paint Thickness	80–120 μm	Corrosion protection; below 80 μm risks early rust.ISO 19840
Operating Temperature	-20–60 °C	Outside range may affect material toughness and welds.
Weight	150–500 kg	Affects crane deflection and installation.
Tolerance on Length	±2 mm	Ensures proper fit with existing boom.ISO 2768-m
Bolt Hole Diameter	18–30 mm	Must match mating flanges.ISO 273
Bolt Hole Spacing	100–200 mm	Pattern must align with existing boom.
Weld Quality	100 %	Full penetration welds; critical for safety.ISO 5817

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Components / BOM

Main Beam Part
Primary load-bearing structural member, typically an I-beam or box section.

Material: High-strength steel
Connection Plates Part
Reinforced plates at each end with pre-drilled holes for bolted or pinned connections to adjacent sections.

Material: Steel plate
Stiffeners Part
Internal or external ribs or plates that prevent buckling and torsional deformation of the main beam.

Material: Steel plate

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Extension Sections.

Applied To / Applications

This component is essential for the following industrial systems and equipment:

Jib Extension

View system integration details

Manufacturers of Extension Sections

Manufacturer profiles associated with Extension Sections.

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Frequently Asked Questions

What is the purpose of an extension section?

An extension section is a modular component that attaches to the main boom of a jib crane to increase its horizontal working radius, allowing the crane to cover a larger area from a fixed pivot point.

How does the rated capacity change with extension length?

The rated capacity typically decreases as the extension length increases, because longer extensions create higher bending moments. Always refer to the manufacturer's load chart for the specific configuration.

What materials are used for extension sections?

Extension sections are typically made of high-strength steel, with material grades such as Q235B to Q355B (per GB/T 1591). The grade is selected based on capacity and span requirements.

What standards apply to extension sections?

Relevant standards include ISO 4301-1 for rated capacity, ISO 8501-1 for surface preparation, ISO 19840 for paint thickness, ISO 2768-m for tolerances, ISO 273 for bolt holes, and ISO 5817 for weld quality. Verify compliance with the manufacturer.

Data Basis

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Preliminary Technical Classification

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pressure:	Not applicable (structural component)
other spec:	Max load capacity: 1-10 tons (varies by model), Max extension length: 1-5 meters per section
temperature:	-20°C to +80°C

Extension Sections

Product Specifications

Industry Taxonomies & Aliases

Applied To / Applications

Industrial Ecosystem & Supply Chain Structure

Application Fit & Sizing Matrix

Reliability & Engineering Risk Analysis

Compliance & Manufacturing Standards