Editorial Technical Reference

Luffing Hinge

This page explains how Luffing Hinge is classified within Other Transport Equipment Manufacturing. Technical values and manufacturer relationships are research references; confirm the current specification and supplier evidence for each order.

Technical Definition & Core Assembly

A specialized hinge mechanism that enables the angular adjustment of a luffing jib on cranes and lifting equipment.

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Product Specifications

Technical details and manufacturing context for Luffing Hinge

Definition
The luffing hinge is a critical mechanical component in luffing jib systems, serving as the pivot point that allows the jib to be raised or lowered (luffed) to adjust its working radius and clearance. It connects the jib to the crane's mast or slewing ring, transmitting loads while permitting controlled rotational movement. This hinge is designed for heavy-duty applications in the transport equipment manufacturing industry, particularly for cranes and other lifting machinery. It operates on a pin-and-bushing or bearing system, allowing rotation around a fixed axis. Hydraulic cylinders or winch systems apply force to one side of the hinge, creating torque that changes the jib's angle. The hinge's design ensures smooth articulation while withstanding significant bending moments, shear forces, and compression loads during lifting operations. The luffing hinge is typically manufactured from high-strength alloy steel or forged steel, with bronze bushings or bearings to reduce friction and wear. Key parameters include a rated load capacity of 50–200 tonnes at minimum radius, a luffing angle range of 0–80 degrees, an operating pressure of 25–35 MPa, a bearing diameter of 300–800 mm, a tolerance of ±0.5 mm (per ISO 2768-m), an operating temperature range of -20 to 60 degrees Celsius, ingress protection ratings of IP65–IP67 (per IEC 60529), material grades Q345B–Q460C (per GB/T 1591), and a weight of 1500–5000 kg. These values are directory reference ranges and must be confirmed for the specific model and application. The hinge is a component that requires careful selection based on crane design, load requirements, and environmental conditions. Verification of model-specific values and standards should be conducted with the legal manufacturer or supplier.
Working Principle
The luffing hinge operates on a pin-and-bushing or bearing system, allowing rotation around a fixed axis. Hydraulic cylinders or winch systems apply force to one side of the hinge, creating torque that changes the jib's angle. The hinge's design ensures smooth articulation while withstanding significant bending moments, shear forces, and compression loads during lifting operations. The hinge must be properly lubricated and sealed to maintain performance and prevent contamination.
Common Materials
High-strength alloy steel, Forged steel, Bronze bushings/bearings
Technical Parameters
ParameterTypical rangeNotes & selection driver
Rated Load Capacity50–200 tMaximum load at minimum radius
Luffing Angle Range0–80 °Full range for jib positioning
Operating Pressure25–35 MPaHydraulic system pressure
Bearing Diameter300–800 mmMatches jib size
Tolerance±0.5 mmEnsures alignmentISO 2768-m
Operating Temperature-20–60 °CSeals and lubrication limits
Ingress ProtectionIP65–IP67Dust and water resistanceIEC 60529
Material GradeQ345B–Q460CHigh-strength steelGB/T 1591
Weight1500–5000 kgAffects crane counterweight

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
  • Hinge Pin Part
    Central axle providing the pivot point for rotation
    Material: Hardened alloy steel
  • Bushings/Bearings Part
    Reduce friction between moving parts and distribute loads
    Material: Bronze or roller bearings
  • Hinge Plates Part
    Structural plates that connect to jib and mast, transmitting forces
    Material: High-strength steel plate
  • Lubrication Ports Part
    Provide access for greasing moving components
    Material: Steel fittings

Application & selection

Application Fit & Sizing Matrix

Operational Limits
pressure: Not applicable (mechanical component)
other spec: Max angular deflection: ±15°, Max dynamic load: 50 kN, Max static load: 75 kN
temperature: -40°C to +80°C
Media Compatibility
✓ Structural steel environments ✓ Marine-grade atmospheres ✓ Industrial lubricated applications
Unsuitable: High-concentration abrasive particulate environments
Sizing Data Required
  • Maximum expected moment load (kN·m)
  • Required angular range of motion (degrees)
  • Mounting interface dimensions and bolt pattern

Risk, maintenance & compliance

Reliability & Engineering Risk Analysis

Failure Mode & Root Cause
Wear and deformation of hinge pin and bushing
Cause: Inadequate lubrication leading to metal-on-metal contact, combined with cyclic loading and misalignment causing uneven stress distribution
Cracking and fatigue failure in hinge plate welds
Cause: Stress concentration at weld toes due to poor weld geometry, combined with dynamic loading from luffing operations exceeding design limits
Maintenance Indicators
  • Audible grinding or popping sounds during luffing movements
  • Visible misalignment or uneven gap between hinge plates during static inspection
Engineering Tips
  • Implement precision laser alignment during installation and periodic checks to ensure proper hinge geometry and load distribution
  • Establish condition-based lubrication program using high-temperature, extreme-pressure grease with regular sampling to monitor wear particles

Indicative industry ranges for design and RFQ preparation. Confirm the exact figures and applicable standard with the manufacturer before specifying.

Compliance & Manufacturing Standards

Applicable Standards
ISO 5817:2014 - Welding - Fusion-welded joints in steel, nickel, titanium and their alloys (beam welding excluded) - Quality levels for imperfections ANSI/ASME B30.5 - Mobile and Locomotive Cranes DIN EN 13001-3-1:2012 - Cranes - General design - Part 3-1: Limit states and proof of competence of steel structures

Quoted from the published standard.

Manufacturing Precision
  • Bore diameter: +/-0.025 mm
  • Surface flatness: 0.15 mm per meter
Quality Inspection
  • Magnetic Particle Inspection (MPI) for surface cracks
  • Hardness testing (Rockwell C scale) for material verification
Technical documentation
Request current drawings, revision history, and a signed specification sheet.
Manufacturing capability
Verify equipment lists, process limits, capacity, and representative production evidence.
Inspection readiness
Confirm test methods, calibrated equipment, sampling plans, and traceable reports.
Supplier transparency
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Manufacturers of Luffing Hinge

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Frequently Asked Questions

What is the primary function of a luffing hinge?

The luffing hinge serves as the pivot point for a luffing jib, allowing it to be raised or lowered to adjust the working radius and clearance of the crane.

What materials are commonly used for luffing hinges?

High-strength alloy steel, forged steel, and bronze bushings or bearings are typical materials, as listed in the directory.

What are the key parameters to consider when selecting a luffing hinge?

Key parameters include rated load capacity, luffing angle range, operating pressure, bearing diameter, tolerance, operating temperature, ingress protection, material grade, and weight. These must be verified for the specific application.

How should I verify the suitability of a luffing hinge for my crane?

Consult the legal manufacturer or supplier to confirm that the hinge's specifications match your crane's design, load requirements, and environmental conditions. Always verify model-specific values and standards.

Data basis: editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Related equipment

Applied To / Applications

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

Luffing Jib
View system integration details

Industrial Ecosystem & Supply Chain Structure

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Luffing Hinge.

Luffing Joint Jib Hinge

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records.

Preliminary Technical Classification
This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Compiled and source-reviewed by the CNFX editorial team. Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review · Page last updated 12 October 2026

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