Heavy Duty Qd Overhead Crane

What is a QD Overhead Crane?

QD generally refers to a double-girder overhead crane model designed for heavy duty industrial lifting-also called an EOT (Electric Overhead Traveling) crane. Key features include:

Double girder (double beam) structure for higher load capacity and rigidity. jrcranegroup.

Heavy-duty working class (A5–A7, sometimes up to A8), meaning it's built for frequent, demanding lifting tasks. 

Large lifting capacities, often from ~5 ton up to 500 ton or more depending on configuration. 

Used in factories, warehouses, steel mills, power plants, ports, etc. for material handling. 

These cranes travel longitudinally on runway rails and have a trolley that moves laterally, with hooks (or specialized attachments) lifting and lowering loads. 

 

Overhead & Bridge Crane Options

Double Girder Overhead Cranes – Heavy-duty overhead crane solutions with larger lifting capacities suitable for industrial use (more robust than light kits).

20 Ton R&M QX Overhead Crane Kit – Large-capacity kit for heavy applications (e.g., fabrication/warehouse).

R&M Overhead Crane Kit with Hoist – Complete crane solution with hoist for heavy material handling.

Complete Free Standing Overhead Bridge Crane – Freestanding option if no runway structure exists.

 

QD vs STANDARD OVERHEAD CRANES

Aspect	Heavy Duty QD Crane	Standard Duty Crane
Duty Class	A6-A8 (M6-M8)	A3-A5 (M3-M5)
Design Life	30+ years	20-25 years
Safety Factor	Higher (5.5-6:1)	Standard (5:1)
Component Quality	Premium, heavy-duty	Standard industrial
Control System	Advanced, often with VFD	Basic relay or simple PLC
Maintenance	More frequent, predictive	Standard scheduled
Price Premium	25-50% higher	Base price
Best For	Continuous, demanding use	Intermittent, general use

 

TECHNICAL SPECIFICATIONS EXAMPLE

Lifting Capacity Up to 500+ tons for specialized applications
Duty Classification Equivalent to FEM M6, M7, M8
Span Up to 40m+ with custom engineering
Lift Height Up to 50m for special installations
Work Cycles Continuous operation in some applications

Here's a clear breakdown of the main components of a heavy-duty QD model double-girder overhead crane - the type commonly used in industrial material handling (often called a double-girder EOT crane) and designed for high load capacities and frequent operation:

Bridge Structure (Steel Structure)

Main Girders (Double Girders)
Box-type welded steel beams that carry the load and trolley

End Carriages (End Trucks)
Connect the main girders and run on runway rails

Walkways & Handrails
Maintenance access platforms on the bridge

 

Lifting Mechanism

Hoist Assembly

Hoisting motor

Gear reducer

Wire rope drum

Wire ropes

Hook Block

Main hook

Auxiliary hook (optional, for heavy duty)

Pulley / Sheave System

Trolley Mechanism

Trolley Frame

Trolley Travel Motor

Gear Reducer

Trolley Wheels

Brake System

The trolley moves across the bridge carrying the hoisting mechanism.

 

Crane Travel Mechanism

Bridge Travel Motors

Reducers / Gearboxes

Crane Wheels

Brakes

Wheel Buffers

This mechanism moves the entire crane along the runway rails.

 

Electrical & Control System

Main Electrical Control Cabinet

Frequency Inverters (VFD) – optional

Limit Switches (Hoist & Travel)

Overload Protection System

Control Relays & Contactors

Power Distribution Components

 

Power Supply System

Busbar / Conductor Rail System
Supplies power to the crane

Festoon Cable System
Supplies power to the trolley

Cable Trolleys & Cable Collectors

 

Operator Control System

Pendant Control

Radio Remote Control

Operator Cabin (Cab Control) – for heavy duty & high capacity cranes

Safety Devices

Overload limiter

Upper & lower hoisting limit switches

Travel limit switches

Emergency stop button

Rail clamps / wind clamps (outdoor use)

Anti-collision device (multiple cranes)

Buffer stops

Auxiliary Components

Lubrication system

Nameplates & load charts

Bolts, fasteners, pins

Paint & corrosion protection system

Sketch

Main technical

 

 

Advantages of Heavy-Duty QD Overhead Crane

1. High Load Capacity & Structural Strength

Double-girder box structure provides excellent rigidity and load distribution

Suitable for medium to ultra-heavy lifting, typically 5–500+ tons

Minimal deflection under full load, ensuring safe and stable operation

2. Heavy-Duty Working Class

Designed for high-frequency and continuous operation

Working duty classification usually A5–A7 (FEM 2m–4m)

Ideal for harsh industrial environments with repetitive lifting cycles

3. Large Span & High Lifting Height

Supports large spans and greater hook travel

Allows maximum utilization of workshop space

Suitable for factories with wide bays and tall buildings

4. High Lifting Efficiency

Independent motions for:

Hoisting

Trolley traveling

Bridge traveling

Enables fast, precise, and efficient material handling

Reduces production downtime and labor costs

5. Flexible Configuration Options

Available with:

Main + auxiliary hoist

Cabin, pendant, or remote control

Variable Frequency Drives (VFD)

Can be customized for heat resistance, dust protection, explosion-proof, etc.

6. Excellent Safety Performance

Equipped with comprehensive safety devices:

Overload limiter

Limit switches

Emergency stop

Anti-collision system

Conforms to ISO, FEM, GB, and CE standards

7.Easy Maintenance & Long Service Life

Walkways and maintenance platforms improve accessibility

Modular components allow quick replacement and servicing

High-quality materials ensure long operational lifespan

 

Applications of Heavy-Duty QD Overhead Crane

1.Manufacturing & Industrial Plants

Machinery manufacturing

Heavy equipment assembly

Mold and die handling

Large component positioning

2.Steel & Metallurgical Industry

Steel mills

Rolling workshops

Foundries

Billet, slab, and coil handling

3.Power & Energy Industry

Power plant construction

Turbine and generator installation

Transformer handling

Nuclear and thermal power facilities

4.Shipbuilding & Heavy Fabrication

Shipyards

Offshore structure fabrication

Large welded assemblies

Module lifting operations

5.Construction & Infrastructure

Bridge construction plants

Precast concrete yards

Large steel structure workshops

Tunnel and shield machine assembly

6.Warehousing & Logistics (Heavy Load)

Steel material warehouses

Machinery storage facilities

Port inland logistics centers

Heavy cargo transfer stations

 

Heavy-Duty QD Overhead Crane Production Process

1. Design & Engineering

Load capacity, span, lifting height, duty class confirmation

Structural strength calculation (girder deflection, stress analysis)

Selection of hoist, motors, reducers, brakes, and electrical system

Drawing output: general arrangement, girder drawings, electrical schematics

Standards applied: GB / FEM / ISO / CE (as required)

2.Raw Material Preparation

High-strength structural steel plates and sections

Steel inspection:

Thickness verification

Mechanical property testing

Surface defect inspection

Certified materials used for heavy-duty applications

3. Main Girder Fabrication

Steel plate cutting (CNC flame / plasma cutting)

Assembly of box-type double girders

Automatic submerged arc welding

Weld seam inspection (UT / MT where required)

Girder cambering and straightness correction

4.End Carriage Manufacturing

End beam welding and machining

Installation of:

Crane wheels

Bearings

Gear reducers

Travel motors

Braking systems

Alignment and dimensional accuracy check

5. Machining & Component Processing

Precision machining of:

Wheel shafts

Bearing seats

Connection flanges

Surface treatment of machined parts

Trial assembly of mechanical components

6. Hoisting & Trolley Assembly

Assembly of hoisting mechanism:

Hoist motor

Gear reducer

Wire rope drum

Wire ropes

Hook block (main & auxiliary if required)

Trolley frame assembly

Trolley running test and brake adjustment

7. Electrical System Installation

Installation of:

Control cabinet

Motors and limit switches

Overload protection system

VFD (if specified)

Wiring of:

Bridge travel system

Trolley travel system

Hoisting system

Electrical insulation and continuity testing

8.Surface Treatment & Painting

Shot blasting to Sa2.5 standard

Anti-corrosion primer coating

Intermediate and finish paint application

Color and thickness inspection

Special coatings available (marine, heat-resistant, epoxy)

9.Pre-Assembly & Factory Testing

Full crane pre-assembly (or major assemblies)

No-load operation test

Load test (static & dynamic)

Travel, hoisting, braking, and limit switch testing

Noise and vibration inspection

10.Quality Inspection & Certification

Dimensional inspection

Welding quality inspection

Electrical safety inspection

Load test certification

Third-party inspection (SGS, BV, TUV if required)

11.Packing & Delivery

Disassembly for transport

Export-standard packing:

Steel structures protected

Electrical parts sealed

Spare parts labeled

Documentation:

User manual

Test certificates

Installation drawings

Quality certificates

Workshop view:

The company has installed an intelligent equipment management platform, and has installed 310 sets (sets) of handling and welding robots. After the completion of the plan, there will be more than 500 sets (sets), and the equipment networking rate will reach 95%. 32 welding lines have been put into use, 50 are planned to be installed, and the automation rate of the entire product line has reached 85%.