How to Select a Double Girder Gantry Crane?

The core of selecting a double girder gantry crane (gantry crane) is: first, determine the application scenario and model → then calculate the three core parameters → match the working level → select the lifting gear and configuration → finally, verify compliance with the manufacturer. The complete selection method is given below step by step.

I. First, clarify the application scenario and model. The mainstream double girder gantry crane is the MG type (universal hook), with other variations such as grab bucket (MZ), container-specific, and electromagnetic chuck.

Table

Scenario | Recommended Model | Typical Working Level | Core Requirements

Workshop/Factory | MG Type (Standard Double Beam) | A4–A5 | Precision, Low Noise, Safety Protection

Outdoor Freight Yard/Stock Yard | MG Hook/MZ Grab Bucket | A5–A6 | Wear-resistant, Dustproof, Windproof

Port/Dock | MG Heavy-duty/Container Dedicated | A6–A7 | Heavy-duty, High Frequency, Corrosion-resistant, Windproof

Metallurgy/Heavy Manufacturing | Extra Heavy-duty | MG A7–A8 | High Temperature Resistance, High Strength, Continuous Operation

II. Determine the Three Core Parameters (Required)

1. Rated Lifting Capacity Q (t) Select model based on the maximum single-piece cargo weight + 10%–20% safety margin.

Example: Maximum piece 20t → Recommended 25t; ≥20t usually uses main and auxiliary hooks (auxiliary hook 1/3–1/5 of the main hook).

1. **Standard Tonnage Series:** 5/10/16/20/25/32/50/75/100t, etc.

2. **Span S (m)**
Span = Distance between the center lines of the two tracks.

Outdoor: Determined by the working coverage width; avoid blindly increasing spans (cost, energy consumption, and wheel pressure will increase simultaneously).

Indoor: Factory span - 0.5–1m safety distance on each side.

Common spans: 18/22/26/30/35m; Large spans (>30m) commonly use rigid-flexible outriggers + alignment devices.

3. **Lifting Height H (m)**
Lifting height = Distance from the lowest point of the hook to the ground/top surface of the track.

Calculation: Maximum cargo height + lifting device height + safety margin (0.5–1m).

Common: 8/10/12/16/20m; Extra-high sizes can be customized.

III. Working Class (Most Critical, Determining Lifespan and Reliability)
According to GB/T 3811, working classes are divided into A1 (Light) – A8 (Extra Heavy), determined by both load condition and utilization level.

Table: Working Class | Applicable Scenarios | Annual Operating Cycles

A1–A3 | Occasional Use (Warehouse, Auxiliary) | <100,000

A4–A5 | Daily Production (Workshop, Yard) | 100,000–500,000

A6–A7 | Continuous Heavy Load (Port, Metallurgy) | 500,000–2,000,000

A8 | Extra Heavy Continuous (Steelmaking, Heavy Lifting) | >2,000,000

⚠️ Low-level selection is strictly prohibited for high-frequency heavy load scenarios (e.g., A4 will cause rapid damage in ports).

IV. Lifting Gear and Functional Configuration
Select lifting gear according to material type to determine the overall applicability of the machine:

Hook: General-purpose cargo (standard configuration).

Grab Bucket: Bulk materials (coal, ore, grain) → MZ type.

Electromagnetic Chuck: Steel, scrap steel → Equipped with electromagnetic system.

Container Spreader: Port containers → Dedicated telescopic spreader.

Double Hook / Multi Hook: For long and heavy items, precision assembly.

V. Environmental and Safety Configuration
Outdoor / Port: Windproof rail clamps, anchoring devices, heavy-duty anti-corrosion paint (epoxy zinc-rich + polyurethane).

Dust / Corrosion: IP55+ protection, wear-resistant seals, stainless steel components.

Explosion-proof: Explosion-proof motors, explosion-proof electrical components (Ex d IIB T4, etc.).

Intelligent / Speed ​​Control: Variable frequency speed control (lifting/trolley/cart), anti-sway, remote monitoring, positioning.

VI. Drive and Operation Methods
Lifting Mechanism: ≤10t commonly uses electric hoists; >10t uses winches (drum + motor + reducer), supports A6–A8.

Traction Mechanism:
Conventional: Motor + reducer + brake, high cost-performance ratio.

European Style: Three-in-one drive (motor + reducer + brake integrated), compact, efficient, and low-noise.

Operation: Ground buttons, driver's cab, wireless remote control (mainstream).

VII. Selection Process (Recommended)

Site Survey: Track foundation, clearance, environmental conditions.

Requirements Analysis: Maximum weight, operating frequency, material type, annual working hours.

Parameter Calculation: Lifting capacity, span, lifting height, working class.

Model and Configuration: MG/MZ/Container, spreading gear, frequency converter, wind and corrosion resistant.

Manufacturer Verification: Wheel pressure, foundation bearing capacity, non-standard customization.

Selection Quick Reference Guide: Leave a margin in tonnage, don't be greedy with excessive span; calculate height for safety, match the working class; consider the material with the spreading gear, provide environmental protection; choose a reliable drive, safety cannot be forgotten.