Bridge Crane Types Explained: Six Categories, Applications & Selection Guide
On factory floors, in warehouse yards and across metallurgical lines — virtually every industrial setting that handles heavy material horizontally relies on bridge cranes. Mounted overhead, the crane combines cross travel (trolley moving along the bridge girders) and long travel (the whole bridge moving along runway rails), giving operators precise three-dimensional positioning of heavy loads.
But “bridge crane” is a broad family. From routine material handling to molten metal transport, from explosive atmospheres to the powerful electromagnetic fields of an aluminum potroom, different conditions demand very different structural, material, electrical and safety features. Pick the wrong type and the result ranges from poor throughput and frequent breakdowns to serious accidents.
Drawing on national standards (GB/T 14405) and field practice, this guide walks through the six core categories — general-purpose, metallurgical, explosion-proof, insulated, single-girder electric hoist, and double-girder electric hoist — examining each one’s structure, typical applications and selection criteria so engineers and buyers can match the right machine to the job.
1. Definition & Working Principle
What Is a Bridge Crane?
A bridge crane is a crane whose bridge girder is supported on a runway track through travel wheels, or directly on a load-bearing surface.
The definition covers three essentials:
• Bridge girder — the main load-bearing structure, spanning the working area (usually across the building width).
• Travel mechanism — enables the whole crane to move longitudinally along the building rails for wide coverage.
• Support mode — rail-supported in most cases, or directly supported on a load-bearing surface in special applications.
Basic Components
Whatever the type, every bridge crane includes:
| Component | Function |
| Bridge (main girder + end carriages) | Main load-bearing structure; the main girder carries the load, end carriages connect girders and house travel mechanisms |
| Trolley / cross-travel mechanism | Drives the hoist trolley across the main girder |
| Hoisting mechanism | Lifts and lowers loads vertically — the core function unit |
| Long-travel mechanism | Moves the whole crane along the building runway |
| Electrical control system | Controls hoist, cross travel and long travel; includes power distribution, protection and control circuits |
| Safety devices | Limit switches, buffers, overload limiters, brakes and other safety systems |
The differences between categories concentrate in four areas: hoisting mechanism selection, girder reinforcement, special treatment of the electrical system, and targeted safety configuration.
2. General-Purpose Bridge Crane
Definition
A general-purpose bridge crane is a bridge crane for ordinary use in normal environments, whose load-handling device is a hook, grab, electromagnetic lifting magnet, or a combination of two or more of these.
Note: This category excludes bridge cranes that use an electric hoist as the hoisting mechanism.
Key Features
General-purpose bridge cranes are the highest-volume, most widely used type, and the platform on which all other special-purpose variants are built.
• Hoisting mechanism — an independent wire-rope winch (not an electric hoist), with dedicated hoist motor, gearbox and brake.
• Duty group — usually A5–A7, suitable for medium- to high-frequency use.
• Flexible load handling — hook (fabricated parts/molds), grab (bulk materials), lifting magnet (steel plate/scrap), or a combination.
• Capacity range — 5 t to 600 t, span 10.5 m to 31.5 m (larger sizes on request).
Typical Applications
• Machining plants — moving workpieces, mold changes, raw material loading.
• Steel warehouses — lifting steel plate and sections with a magnet.
• Bulk yards — coal, ore and grain handling with a grab.
• Precast yards — lifting and placing concrete elements.
Selection Criteria
| Parameter | Recommendation |
| Capacity | Select 1.1–1.25× the maximum lifted load to leave a margin |
| Span | Match building column spacing; common sizes 16.5, 19.5, 22.5, 25.5, 28.5 and 31.5 m |
| Duty group | A5 for single-shift light use; A6 for two-shift medium use; A7 for three-shift heavy use |
| Lift height | Typically 6–16 m; check clear headroom and the lifting path |
The Yuzhong QD series covers 5 t to 500 t, with SKF bearings and Siemens motors as standard. It supports fast switching between hook, grab and magnet, and fits a wide range of scenarios including machine building, steel storage and port yards.
3. Metallurgical Bridge Crane
Definition
A metallurgical bridge crane is designed to meet the special requirements of metal smelting, casting, rolling and hot working, and is used directly in the production process flow.
Key Features
Metallurgical bridge cranes work under the harshest conditions of all types and carry the highest technical complexity. This is not simply a standard crane with a heat shield — every element, from structural design to component selection, is systematically reinforced around the demands of the metallurgical process.
• High-temperature design — heat shielding under the main girder, electrical equipment and cables rated Class H insulation (180 °C) or above, trolley fitted with a heat shield.
• Extreme duty group — typically A7–A8, supporting nearly continuous three-shift operation.
• Redundant safety — dual braking (main + backup), dual limit switches, overload protection dedicated to molten metal.
• Integrated special functions — tilting, tong, charging or casting-auxiliary mechanisms as the process requires.
• Higher protection ratings — IP54 or above for control cabinets, IP55 or above for motors, to handle high heat and heavy dust.
Typical Applications
| Process | Typical Crane | Function |
| Steelmaking shop | Ladle crane | Lifting steel and iron ladles; requires dual braking and absolute reliability |
| Continuous casting shop | Charging crane | Charging scrap and alloy into the converter |
| Rolling shop | Roll-changing crane | Changing rolls, lifting billets and finished coils |
| Heat-treatment shop | Quenching crane | High-temperature lifting into quenching tanks and tempering furnaces |
Why a General-Purpose Crane Is Not “Good Enough” for Metallurgy
When budgets are tight, some smaller plants try to substitute general-purpose cranes. The risks are serious:
1. Inadequate heat protection — cables and electrical components in a general-purpose crane age rapidly under radiant heat, sharply raising short-circuit and fire risk.
2. No brake redundancy — a general-purpose crane has a single brake. If it fails, a ladle of molten metal tipping over does not bear thinking about.
3. Duty group mismatch — metallurgical shops usually run 24 hours a day. An A5–A7 mechanism may only reach one-third to one-fifth of its design life under A8 duty.
4. Higher maintenance frequency — premature component failure means more downtime; total cost of ownership actually rises.
Yuzhong metallurgical cranes follow GB/T 14405 metallurgical crane technical conditions, with dual braking and Class H insulation, and have run for over 10 years on continuous-casting and rolling lines at several major steel mills.
4. Explosion-Proof Bridge Crane
Definition
An explosion-proof bridge crane is designed for use in explosive gas or explosive dust atmospheres, with certified explosion-proof performance.
Key Features
In petrochemical plants, coal-to-chemicals facilities, flour mills and munitions plants, the air can contain flammable gases, vapors or combustible dust. On an ordinary crane, sparks from electrical switching, heat from mechanical friction, or even metal-on-metal impact can become an ignition source. The core design goal of an explosion-proof bridge crane is to eliminate every possible ignition source.
• Explosion-proof electrical system — every motor, device, switch and junction box uses flameproof (Ex d) or increased-safety (Ex e) construction.
• Spark-free travel mechanism — wheels use copper alloy or specially treated materials to prevent sparking against the rail.
• Anti-static design — the whole crane is bonded with a static-dissipative path to prevent static accumulation.
• Surface temperature control — any surface that could contact an explosive mixture must stay below the ignition temperature of the relevant gas/dust group.
• Rating matched to the site — must precisely match the hazardous area classification (Zone 0/1/2 or 20/21/22) and the substance group (IIA/IIB/IIC or IIIA/IIIB/IIIC).
Reading the Ratings
| Marking | Zone | Typical Substances |
| Ex d IIB T4 | Zone 1 | Ethylene, coke-oven gas |
| Ex d IIC T4 | Zone 1 | Hydrogen, acetylene, carbon disulfide |
| Ex d IIA T3 | Zone 1 | Propane, gasoline, diesel |
| ExtD A21 T130 °C (dust) | Zone 21 | Aluminum, magnesium and coal dust |
| ExtD A22 T130 °C (dust) | Zone 22 | Flour, sugar, wood dust |
Typical Applications
• Petrochemicals — maintenance lifting of equipment and piping in refining units, tank farms and loading racks.
• Coal-to-chemicals — large valve and pipe replacement in gasification and methanol units.
• Grain processing — conveyor maintenance in flour and feed mills.
• Munitions — mold and equipment handling in propellant filling shops (top rating IIC T4).
Non-Negotiable Selection Rules
Selecting an explosion-proof crane is not just “picking a model” — it requires a complete safety case:
1. A design unit with explosion-proof qualifications must do the selection and sizing.
2. The rating must be confirmed by a safety assessment body, not assumed from experience.
3. After installation it must be inspected by the special-equipment authority and issued an explosion-proof certificate before use.
4. Routine maintenance must be carried out by certified explosion-proof electricians; opening enclosures under power is strictly forbidden.
The Yuzhong LHB series explosion-proof double-girder bridge crane covers IIB T4 and IIC T4 ratings and holds a certificate from the National Supervision and Inspection Center for Explosion-Proof Electrical Products. It is suitable for high-risk sites in petrochemicals, chemicals and defense.
5. Insulated Bridge Crane
Definition
An insulated bridge crane is used in non-ferrous metal smelting shops producing aluminum, magnesium, lead, zinc and copper by electrolysis, and provides reliable insulation against strong electric current.
Key Features
The environment in a non-ferrous electrolysis shop is unique — hundreds of thousands of amperes of direct current flow through the pots, creating powerful electromagnetic fields and stray currents. If the crane is not reliably insulated, these stray currents can return through the crane’s metal structure, causing:
• Short-circuited pots — current returns through crane → rail → earth, bypassing the pots and reducing electrolysis efficiency.
• Equipment burnout — large currents at the wheel-rail contact generate high-temperature arcing.
• Electric shock — an operator standing on the crane can become part of the current path.
• Structural corrosion — electrochemical corrosion accelerates metal degradation.
The core design of an insulated bridge crane is to put reliable electrical isolation between the crane’s metal structure and earth (the runway):
| Insulation Point | Measure |
| Crane wheels vs. rail | Insulated wheels or insulating pads under the rail; insulation resistance ≥ 1 MΩ |
| Trolley wheels vs. girder rail | Insulating pads or insulated wheel assemblies |
| Hoisting mechanism vs. structure | Insulated sheave block or insulating rope between hook block and wire rope |
| Control cabinet vs. body | Insulating plate under the cabinet |
| Cables vs. body | All cables fixed with insulating clamps |
Technical Parameters
• Insulation resistance — ≥ 1 MΩ crane-to-earth (≥ 3 MΩ for high-demand sites).
• Withstand voltage — insulating parts must pass 2500 V / 1 min power-frequency withstand test.
• Duty group — typically A6–A8 for continuous electrolysis operation.
• Capacity — based on anode/cathode plate weight and handling needs, commonly 10–50 t.
Typical Applications
• Aluminum smelters — anode assembly, cathode replacement, molten aluminum transfer.
• Zinc smelters — cathode zinc stripping and handling.
• Copper refineries — cathode copper loading/unloading and transfer.
• Magnesium production — pot maintenance and magnesium handling.
Maintenance Focus
Insulation performance is a “live indicator” that degrades as dust accumulates, moisture penetrates and insulating parts age. A scheduled testing regime is essential:
• Every shift — visual check of insulator cleanliness; remove metal dust.
• Weekly — measure crane-to-earth insulation resistance with a 500 V megohmmeter.
• Monthly — full inspection of all insulation points; trend the readings.
• Quarterly — power-frequency withstand test.
If insulation resistance falls below 0.5 MΩ, the crane must be stopped. Running with a known fault is not allowed.
6. Electric Single-Girder Bridge Crane
Definition
An electric single-girder bridge crane uses an electric hoist as its hoisting mechanism and operates on a single main girder in normal environments.
Key Features
The electric single-girder is the “economy model” of the bridge crane family — simple structure, low cost and quick installation, suited to light loads and infrequent use.
• Single main girder — the bridge has just one girder, low self-weight and small added load on the building.
• Electric hoist — a standard hoist (CD1/MD1 or upgraded versions) as the lifting unit; compact and easy to maintain.
• Capacity — typically 0.5–16 t; the economical range is up to 10 t.
• Span — 7.5–22.5 m.
• Duty group — A3–A5, light to medium duty.
How It Differs from a General-Purpose Crane
| Item | Single-Girder | General-Purpose (Hook) |
| Girders | One | Two |
| Hoist mechanism | Electric hoist | Independent winch |
| Max. capacity | 16 t | 600 t+ |
| Duty group | A3–A5 | A5–A7 |
| Cost | Low (about 40–60% of general-purpose) | Higher |
| Usage frequency | Light–medium (2–4 h/day) | Medium–heavy (4–8+ h/day) |
| Installation | Delivered nearly complete or simple assembly | On-site assembly |
Typical Applications
• Small repair shops — lifting workpieces and small equipment.
• Warehouses — light material loading and unloading.
• Assembly lines — moving parts between workstations.
• Injection molding — mold changes and demolded part handling.
Selection Notes
1. Do not overload — the rated capacity is a hard upper limit; “a little over occasionally” is not acceptable.
2. Check lift height — on a single girder, the hoist mounting position determines effective lift height; verify against clear headroom.
3. Assess frequency — if the crane runs more than 4 hours a day or lifts more than 10 times an hour, upgrade to a general-purpose or double-girder hoist crane.
Yuzhong’s European-style single-girder crane uses a low-headroom design that delivers more effective lift height in the same building. Its C-type gearbox hoist covers 0.5 t to 20 t, with smooth running and low noise.
7. Electric Double-Girder Hoist Bridge Crane
Definition
An electric double-girder hoist bridge crane uses an electric hoist as its hoisting mechanism and runs on two main girders in normal environments.
Key Features
This type sits between the single-girder hoist crane and the general-purpose double-girder crane — it combines the economy of an electric hoist with the load capacity of two girders, and performs well at medium loads and medium frequency.
• Double girder — better load capacity and stiffness than a single girder, supporting higher tonnage.
• Electric hoist — the hoist sits on a trolley running on a rail along the top (or bottom) flange of the main girders.
• Capacity — typically 5–50 t (up to 80 t from some manufacturers).
• Span — 10.5–31.5 m.
• Duty group — A4–A6, medium to medium-heavy duty.
How It Differs from the Single-Girder Hoist Crane
| Item | Double-Girder Hoist Crane | Single-Girder |
| Girders | Two | One |
| Capacity | Higher, 5–50 t | Limited, 0.5–16 t |
| Stiffness | High; small deflection under load | Limited; more deflection under heavy load |
| Hoist travel | Hoist trolley runs on girder rail | Hoist fixed under the girder or suspended |
| Max. span | Up to 31.5 m | Usually no more than 22.5 m |
| Cost | Medium | Low |
Typical Applications
• Medium machining plants — efficient handling of large workpieces and equipment.
• Warehousing and logistics — loading, unloading and stacking medium-to-heavy goods.
• Precast yards — lifting and transferring concrete and steel elements.
• Wind tower fabrication — rolling and transferring tower cans (with special lifting beams).
When to Choose It over a General-Purpose Crane
The double-girder hoist crane is the best value when all of these hold:
1. Capacity is within 50 t.
2. Duty group is A4–A6.
3. Hook use dominates; no complex grab or magnet requirements.
4. Lower initial investment and maintenance cost matter.
Total cost (purchase + installation + maintenance) is typically 20–35% lower than a general-purpose crane of the same capacity, while load capacity and service life far exceed a single-girder hoist crane.
8. Selection Decision Matrix
Use this matrix as a quick filter across the six categories:
| Condition | Recommended Type |
| Normal environment; hook/grab/magnet; A5–A7 | General-purpose bridge crane |
| Metal smelting/casting/rolling; high temperature, continuous duty | Metallurgical bridge crane |
| Explosive gas or dust atmosphere | Explosion-proof bridge crane |
| Non-ferrous electrolysis shop; strong current | Insulated bridge crane |
| Light load (≤16 t), infrequent use, tight budget | Electric single-girder bridge crane |
| Medium load (5–50 t), medium frequency, double-girder stiffness needed | Electric double-girder hoist crane |
The final choice should also weigh:
• Building conditions — clear headroom, column spacing, runway capacity.
• Duty regime — shifts, daily running hours, load duration factor.
• Load characteristics — weight, shape, temperature, corrosivity or hazard.
• Safety regulations — mandatory standards and inspection requirements of the industry.
• Life-cycle cost — not just purchase price, but maintenance, energy and replacement cycles.
9. Why Choose Yuzhong?
Selecting the right bridge crane sets the capability boundary; choosing the right manufacturer determines the equipment’s life-cycle value. Henan Yuzhong Crane Group, founded in 1978, has spent nearly half a century in the lifting industry. From a local workshop in Changyuan, Henan, it has grown into a leading supplier serving more than 120 countries and regions.
Nearly 50 Years of Manufacturing Heritage
Since 1978, Yuzhong has witnessed and taken part in the Chinese lifting industry’s full journey from imitation to independent R&D. Nearly five decades of accumulated know-how cannot be rushed through acquisition or relabeling — every weld parameter, every mechanism match, every response to a specific condition comes from hands-on project experience.
Full Product Range
| Series | Range | Highlights |
| QD general-purpose bridge crane | 5–600 t | Hook/grab/magnet compatible |
| MG general-purpose gantry crane | 5–500 t, span 10–40 m | Indoor and outdoor use |
| YZ metallurgical bridge crane | 5–400 t | Dual braking, Class H insulation, A8 duty |
| LHB explosion-proof bridge crane | 5–50 t | IIB T4 / IIC T4 full rating coverage |
| JY insulated bridge crane | 10–50 t | Crane-to-earth insulation ≥ 3 MΩ |
| European-style single/double-girder crane | 0.5–50 t | Low headroom, C-type gearbox hoist |
| Container spreaders/hooks | 35–45 t | Port and intermodal use |
One-stop supply. General and special types designed and built in one factory mean higher parts commonality and simpler maintenance and spare-parts management.
International Certification
Yuzhong products hold the certifications required by major global markets:
• ISO 9001 quality management.
• CE marking for the European Union.
• FEM standards from the European Materials Handling Federation.
• ASME standards from the American Society of Mechanical Engineers.
From mining projects in Southeast Asia to refineries in the Middle East, infrastructure sites in Africa to port terminals in South America, Yuzhong equipment meets local regulations and inspection standards.
Core Components — No “Where We Can Save” Compromises
| Component | Standard Fit | Why It Matters |
| Hoist motor | Siemens | High efficiency, low temperature rise, long life; far lower failure rate than no-name motors |
| Bearings | SKF | Top-tier global brand; less wear and heat, longer service intervals |
| Gearbox | In-house C-type / hardened-face gearbox | Low noise, high efficiency, modular maintenance |
| Brakes | Dual braking (metallurgical/explosion-proof) | Fail-safe design; prevents load drift |
| Electrical system | Schneider/ABB low-voltage components | Reliable, with globally available spares |
Some suppliers cut cost with “local alternatives,” but users quickly find — overheating motors, noisy bearings, contactors replaced again and again — that these hidden costs far exceed the initial saving. Yuzhong fits first-tier components as standard and calculates the total life-cycle bill.
Fast Response
• Drawings in 24 hours — from technical inquiry to design proposal in as little as one working day.
• Standard lead times — 30–45 days for general-purpose, 45–60 days for special types.
• Global after-sales network — exports to 120+ countries, with mature international logistics and on-site installation guidance.
Not Just Equipment, but a Solution
Yuzhong’s scope goes beyond manufacturing:
1. Pre-sales technical consulting — selection and layout proposals based on building conditions, duty parameters and usage regime.
2. Custom design — specialized engineering for non-standard conditions such as extreme heat, heavy corrosion or extra-large span.
3. On-site installation guidance — engineers dispatched to overseas project sites for installation and commissioning.
4. Life-cycle after-sales — spare parts, technical training, remote diagnostics and periodic reviews.
10. FAQ
1. What is the main difference between a general-purpose bridge crane and an electric double-girder hoist crane?
The core difference is the hoisting mechanism. A general-purpose crane uses an independent wire-rope winch (dedicated motor, gearbox and brake), with higher capacity, higher duty group and support for multiple load-handling devices. A double-girder hoist crane uses a standard electric hoist; it is compact, lower cost and easier to maintain, but with lower capacity and duty limits. A simple rule: heavy load and high frequency — general-purpose; medium load and medium frequency — double-girder hoist.
2. Can a metallurgical bridge crane be used in a normal environment?
Technically yes, but economically it makes no sense. Its high-temperature design, dual braking and high duty group push the price 30–60% above a general-purpose crane of the same capacity. In a non-metallurgical setting those features are wasted. The reverse — substituting a general-purpose crane in a metallurgical application — is a serious safety violation.
3. Can the explosion-proof rating be upgraded on site?
No. The rating is determined by structural parameters and materials chosen at design and manufacture; any on-site modification invalidates the original explosion-proof certification. If site conditions change and the hazardous area classification rises, a crane with the proper rating must be installed.
4. How often should insulation resistance be tested on an insulated crane?
At least weekly. A newly installed crane should be tested daily during the initial period, then weekly once stable. If resistance shows a clear downward trend or falls below 0.5 MΩ, stop the crane immediately for repair.
5. What is the largest capacity for an electric single-girder crane?
Conventional designs top out at 16 t capacity and 22.5 m span. Beyond that, choose a double-girder hoist crane or a general-purpose bridge crane. Forcing a single girder to higher capacity or span causes excessive deflection and unstable running, with serious safety risks.
Reference standards: GB/T 14405 General-Purpose Bridge Cranes; GB/T 14406 General-Purpose Gantry Cranes; GB 3836 Explosive Atmospheres series; JB/T 7688 Technical Conditions for Metallurgical Cranes.
