QZ Grab Double Girder Overhead Crane

Key Features

Double Girder Design

Stronger than single girder cranes, suitable for heavy loads (5-550 tons or more).

Provides higher hook height for better vertical space utilization.

Grab Bucket System

Used for loose material handling (e.g., sand, gravel, coal, grain).

Can be clamshell, orange peel, or electro-hydraulic grab.

Operates via rope or motorized mechanism.

High Lifting & Traveling Speed

Optimized for fast loading/unloading cycles.

Equipped with variable frequency drives (VFDs) for smooth control.

Robust Construction

Heavy-duty welded steel girders for long service life.

Reinforced end carriages and wheels for stability.

Advanced Control System

Pendant control, cabin-operated, or remote-controlled.

Overload protection, limit switches, and anti-sway technology.

Installation & Maintenance Tips

Proper Rail Alignment – Ensures smooth crane movement.

Regular Grab Inspection – Check for wear in ropes, motors, and jaws.

Lubrication – Keep wheels, gears, and bearings well-greased.

Electrical Checks – Inspect cables, limit switches, and controls.

Comparison with Other Grab Cranes

Core Components：Bearing, Gearbox, Motor, Pump

Place of Origin：Henan, China

Warranty：1 Year

Weight (KG)：2000 kg

Video outgoing-inspection：Provided

Machinery Test Report：Provided

Design：Double beam

Effectiveness：high efficiency

Operating speed：High speed operation

Stability：Anti-swing function

Color：Optional

Power Source：110V/220V/230V/380V/440V,customized

Span：7.5-31.5m

The QZ Grab Double Girder Overhead Crane is a heavy-duty lifting system designed for bulk material handling. Below is a detailed breakdown of its structural, mechanical, electrical, and safety components.

1. Main Structural Components
A. Bridge Girder (Main Beam)
Double box girder design (heavy-duty welded steel construction).

Provides higher load capacity (up to 550+ tons) and better hook height than single girder cranes.

Includes reinforced end connections for stability.

B. End Carriages (Support Structure)
Steel-framed structures at each end of the bridge.

Equipped with wheels, motors, and buffers for movement along the runway rails.

Anti-lift devices prevent derailment.

C. Runway System (Supporting Rails)
Crane rails (QU70/QU80/QU120) mounted on runway beams.

Rail clamps secure the crane when not in use.

2. Lifting & Hoisting Mechanism
A. Grab Bucket (Material Handling Unit)
Types:

Clamshell Grab (for free-flowing materials like sand, grain).

Orange Peel Grab (for scrap metal, rocks, irregular shapes).

Electro-Hydraulic Grab (for precise control).

Rope-operated or motorized (depending on model).

B. Hoist Unit (Lifting System)
Wire rope hoist (for heavy-duty applications).

Dual-motor system (one for lifting/lowering, one for grab opening/closing).

Includes drum, brake, gearbox, and motor.

C. Trolley (Transverse Movement Unit)
Moves along the bridge girder to position the grab.

Contains the hoist, grab control system, and travel motors.

VFD-controlled for smooth acceleration/deceleration.

3. Drive & Motion Systems
A. Long Travel Drive (Bridge Movement)
Motors, gearboxes, and wheels for moving the entire crane along the runway.

Frequency-controlled for precise positioning.

B. Cross Travel Drive (Trolley Movement)
Allows the trolley to move side-to-side along the girder.

Equipped with anti-sway technology for stability.

C. Power Supply System
Festoon or cable reels for electrical power transmission.

Slip ring systems (for 360° rotation in some models).

4. Control & Electrical Systems
A. Control Panel (Main Electrical Cabinet)
Houses contactors, PLCs, and overload relays.

Ensures smooth operation & safety interlocks.

B. Operator Controls
Pendant control (handheld, wired remote).

Radio remote control (wireless operation).

Operator cabin (for large cranes, with joystick controls).

C. Sensors & Limit Switches
Hoist upper/lower limit switches (prevents over-travel).

Trolley end stops (prevents collisions).

Load cell (overload protection).

.

5. Safety Components
A. Braking System
Emergency brakes (mechanical or hydraulic).

Fail-safe holding brakes (prevents accidental drops).

B. Anti-Collision System
Laser/ultrasonic sensors (for multi-crane operations).

Bumper buffers (shock absorption at rail ends).

C. Emergency Stop (E-Stop)
Installed on control panels & pendant remotes.

D. Warning Devices
Sirens & strobe lights (for operational alerts).

6. Optional Accessories
✔ Weighing System (real-time load measurement).
✔ Wind Speed Monitor (for outdoor cranes).
✔ Automated Positioning System (for precise grabs).
✔ Dustproof & Corrosion-Resistant Coating (for harsh environments).

SKETCH

Main technical

Key Advantages

Superior Lifting Capacity

Handles 5-550+ tons, ideal for heavy bulk materials (coal, ore, scrap metal).

High Efficiency

Dual-motor system enables simultaneous lifting and grab operation, speeding up material transfer.

2-3× faster than manual/single-girder alternatives.

Precision Control

VFD drives enable smooth acceleration/positioning (≤±10mm accuracy).

Anti-sway technology minimizes material spillage.

Durable Construction

Welded steel girders withstand 10,000+ duty cycles (M5-M8 classification).

IP55 protection for harsh environments (dust, moisture).

Space Optimization

Double girder design provides 15-20% more hook height vs. single girder cranes.

Safety Features

Dual braking systems + overload protection (110% capacity cutoff).

Emergency power-off (EPO) and collision avoidance.

Primary Applications

1. Design & Engineering
Customer Requirements Analysis
Load capacity, span, lift height, working class, environment, etc.
Mechanical & Electrical Design
3D modeling with CAD/CAE software
Structural analysis, FEM calculation, and layout optimization
Component Selection
Motors, gearbox, hoisting units, brakes, electrical parts from trusted brands
2. Raw Material Procurement
High-quality materials such as Q235B / Q345B steel for main girder fabrication
Certified and traceable materials for safety-critical components
Inspection and testing of incoming materials (chemical & mechanical properties)
3. Steel Structure Fabrication
Cutting: CNC flame/plasma cutting machines for high precision
Beveling & Drilling: Edge preparation and joint drilling
Welding: CO₂/MIG/MAG welding for main beams, end carriages, trolleys
Welds are tested by ultrasonic or magnetic particle inspection
Straightening: Hydraulic press for removing deformation
Assembly: Girder assembly with strict geometric dimension control
4. Surface Treatment
Shot blasting to Sa2.5 standard for rust removal
Epoxy or polyurethane painting
Primer + intermediate + finish coats (typically 80–120μm total thickness)
Optional: Zinc-rich or corrosion-resistant coatings for marine or outdoor use
5. Machining & Assembly
Machining of wheels, shafts, drums, and pulley groups for tight tolerances
Assembly of:
Crane wheels, end carriages, and coupling systems
Trolley frame with hoisting mechanism
Motor, gearbox, drum, hook, and rope guide
6. Electrical System Installation
Electrical cabinet assembly with Siemens/Schneider/ABB components
Installation of:
Limit switches, overload protectors, anti-collision sensors
Cables, festoon systems, and wireless remote systems
Motors with VFDs for smooth speed control (optional)
7. Inspection & Testing
Dimensional Inspection: Ensuring assembly accuracy
No-load Testing: Trolley travel, crane travel, hoisting function
Load Testing (usually 1.1–1.25× rated capacity):
Static & dynamic tests per national or CE standards
Electrical Testing: Insulation resistance, control logic, emergency stop
Safety Device Test: Limit switches, alarms, brakes, and interlocks
8. Packaging & Delivery
Disassembly of main components for shipping (as required)
Waterproof wrapping, anti-corrosion protection, and steel frame packaging
Custom packing for overseas shipment (container or bulk cargo)
9. Documentation & Handover
Includes:
User Manual
Quality Certificate
Load Test Report
Electrical Wiring Diagram
Maintenance Schedule
Optional: On-site installation supervision, commissioning & operator training

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%.