Single Trolley with Two Hooks double Girder Bridge Crane

A single trolley with double hook overhead crane means that there is only one trolley on the main crane girder, but this one trolley is equipped with two hooks, often referred to as the main hook and the secondary hook. The lifting capacity of the main hook is usually higher, while the lifting capacity of the secondary hook is lower. This configuration is ideal for lifting irregular objects, and because single-hook designs are not stable and have limited maneuverability, cranes equipped with a secondary hook tend to be more stable and can assist in turning objects. Ideal for equipment maintenance as well as the processing industry.

Structure & Components of Single Trolley with Two Hooks Double‑Girder Bridge Crane

The single trolley with two hooks double-girder bridge crane is designed for difficult and heavy-duty lifting applications that necessitate simultaneous or sequential dual hook operation. This crane is commonly employed in industries such as heavy machinery, mold production, metallurgy, and power generation, where lifting large or asymmetrical loads need not only high capacity but also perfect load balancing and control. The following is a detailed description of its structural and mechanical components.

1. Main Girder Construction

The crane's main load-bearing structure is made up of two parallel steel girders, which can be either box-type welded profiles or I-beams, and was designed using advanced finite element analysis software. This ensures maximum structural rigidity and minimal deflection, even under full dual-hook loads. These girders span the whole working area, supporting both the trolley and the load. Load forces are delivered to end trucks, which have precision-ground steel wheels. Internal stiffeners and diaphragms are also used in the girders to withstand the torsional and vertical loads that arise during multi-point lifting.

2. Trolley Frame & Hoist Mounting

The trolley serves as a sturdy carrying structure, constructed of structural-grade steel with stress-relieved welds to prevent deformation. Hook spacing can be changed to fit various load geometries. The trolley runs on hardened rails mounted on the girders, which are supported by low-maintenance bearings and gear reducers. All moving parts are engineered to withstand high duty cycles and offer long-term dependability.

3. Runway And End‑Truck Assembly

The runway system is made up of parallel rails mounted on fixed supports that are either integrated into the building construction or freestanding steel columns. The end trucks, which house motorized driving wheels, have adjustable wheelbases to allow slight rail misalignment. Each wheel set incorporates anti-derailment brackets and side guide rollers to provide crane stability and avoid misalignment during acceleration, braking, or crosswinds. Lubrication points and access gates provide efficient maintenance.

4. Motor & Drive Components

Conical rotor squirrel-cage motors provide drive power and include electro-mechanical disc brakes. These motors provide high starting torque, which is critical for load lifting and travel activities, while keeping operating temperatures low. The motors are class B or F insulated and have an IP44/IP54 grade for dust and moisture protection. They drive helical gear reducers, which are housed in precision-machined cast-iron housings for long-term reliability, silent operation, and decreased vibration during high-frequency operation.

5. Rope Drum & Wire Rope

The rope drum is made of precision-welded steel and machined for concentric balance, with a cast-iron winding core for additional strength. Nylon or bronze rope guides prevent crossover and ensure seamless cable wrapping. The hoisting mechanism employs 6×37+1 steel-wire ropes meeting GB/T 20118-2006 requirements, which are noted for their flexibility, high tensile strength, and wear resistance. These ropes are coiled in numerous layers to increase lifting height while reducing wear.

6. Hooks & Safety Devices

Both hooks are forged from high-quality carbon steel or alloy steel and can withstand up to three times their rated static load for increased safety. Each hook has a spring-loaded clasp that prevents slings or loads from being accidentally disengaged. Mechanical stoppers, higher and lower travel limit switches, and overload limiters are also included as additional safety precautions. These overload devices are electronically calibrated and modular, with built-in diagnostics to avoid overloading and provide smooth, safe lifting.

7. Electrical Systems & Control

The crane's electrical system is contained in a weather-sealed control cabinet that allows for quick troubleshooting and component replacement. Heavy-duty insulated conductor bars or festoon cable systems are used to transmit power, ensuring uninterrupted energy delivery. The crane is controlled via a pendant with IP65-rated buttons and an optional wireless remote for enhanced convenience. Both systems have emergency stop buttons, dual-speed control, and lockout features to prevent unauthorized use or unintentional starts, which improves both safety and operational control.

Advantages

The single trolley has two hooks. Bridge crane design is a specialized solution that boosts performance and efficiency in difficult material handling applications. This crane system achieves a combination of cost, control, and space efficiency by combining two independently controlled lifting hooks on a single trolley frame. It is particularly useful in manufacturing settings where huge, heavy, or sensitive objects must be lifted in a coordinated manner. The benefits are detailed below, with a focus on the operational and technical features that make it an excellent choice in precision-oriented industries.

1. Load Stability And Control

A single trolley system with two hooks allows for better control over load orientation while lifting. By allowing both hooks to function synchronously or independently, operators may uniformly distribute the lifting power and stabilize uneven or flexible loads such as long metal beams, composite panels, or prefabricated assemblies. This minimizes wobble, tilt, and torsional stress, which could harm delicate materials. This capability greatly enhances quality assurance and safety in industries such as aerospace, railcar assembly, and wind turbine production that require precise component alignment.

2. Reduced Infrastructure Costs

By combining two lifting points into a single trolley, this crane design reduces structural and electrical complexity. In contrast to dual-trolley cranes, which require complete duplication, just one trolley frame, one set of driving motors, and one control panel are needed. This directly decreases capital expenditures for bridge drives, cabling, and motor starters. It also allows for a thinner bridge beam and lower support beam loads, which could reduce the cost of runway installation and building changes.

3. Lower Maintenance Complexity

The use of a single centralized trolley decreases the amount of moving assemblies that must be fixed and replaced over time, including wheels, gearboxes, motors, and brake systems. Preventive maintenance becomes more predictable and labor-intensive as professionals concentrate primarily on a single drive system. Furthermore, because the electrical and mechanical components are integrated, there is less wiring complexity and fewer potential failure points, resulting in higher uptime and quicker troubleshooting.

4. Optimized Headroom and Hook Approach

A single-trolley, dual-hook system provides for a more compact and efficient design than dual-trolley cranes, which require longer spans and larger structural clearances. It keeps the maximum hook approach—the shortest distance the hook can travel to the wall or runway edge—on both sides without having to widen the bridge. Furthermore, this configuration decreases the crane's overall profile, making it ideal for retrofit projects or new installations in facilities with low ceiling heights, such as underground workshops, test bays, or small-footprint warehouses.

Dual-Hook Operational Mechanics

In applications that need careful handling of lengthy, uneven, or heavy loads, a single trolley fitted with two hooks on a double girder bridge crane provides flexibility and stability. This layout is particularly beneficial in industries such as mold fabrication, turbine assembly, pressure vessel handling, and others where the load's center of gravity moves during lifting or symmetrical lifting is required. The system allows for both synchronized and independent hook operation, facilitating safe load rotation, accurate positioning, and ideal weight distribution—all while adhering to international safety requirements.

1. Precision Control and Load Management

The dual-hook system is designed to provide precise control over load movement and balance, reducing the dangers associated with unequal weight distribution and unexpected load shifts. Operators may easily control both hooks from a single interface, switching between synchronized lifting and individual adjustments based on the task at hand.

2. Load Distribution Monitoring

To maintain load symmetry and structural integrity, strain gauges are incorporated in the trolley frame and hoisting components. These sensors feed real-time load data into the crane's core PLC system. If an imbalance is detected—such as one hook holding more than 60% of the total load—the system sends an auditory and visual alarm to the operator. Further hoisting operations are temporarily restricted to prevent equipment overloading or inadvertent tipping, in accordance with ANSI/ASME B30.2 safety requirements. This proactive function is critical for reducing cable breakage, hook misalignment, and frame deformation during lifting activities with awkward or extended goods.

3. Speed Synchronization

Both hoist motors include Variable Frequency Drives (VFDs) for precise speed synchronization between hooks, typically ranging from 0.5-8m/min. During synchronized operation, both hooks lift and lower at perfectly matched rates, keeping lengthy components level. This is especially handy for lifting or lowering over long distances or operating in tight production bays.

4. Anti-Sway Technology

Smooth load conveyance is another important component of dual-hook crane operation, particularly in areas with limited space or high traffic. Acceleration and deceleration are regulated by an inverter for both trolley and bridge travel. This progressively raises or decreases speed, so stabilizing the load and reducing pendulum motion. The crane's load sway limit of ≤5° improves safety in multi-crane operations and limited workplaces, while also reducing cycle time by eliminating the need for manual steadying. This precision is critical for moving heavy equipment over narrow pits, erecting massive structures, or operating near delicate gear.

Overall, Yuantai's dual-hook single trolley system is a highly advanced solution for precise lifting and safe load handling. It provides real-time load distribution monitoring, synchronized VFD control, and anti-sway motion algorithms in demanding industrial situations, bringing both performance and peace of mind.

Applications

1. Aerospace And Composite Manufacturing

Long fuselage sections, wing assemblies, and composite panels often demand two‑point lifting to avoid deformation. Dual‑hook cranes deliver the necessary stability and precision for these delicate components.

2. Power Plant Maintenance

Large turbines, generators, and heat exchangers require balanced lifts at multiple points. A single trolley with two hooks enables removal and installation with minimal load sway, improving safety and alignment during maintenance.

3. Shipyards And Maritime Operations

Ship sections, lifeboats, and deck machinery often need dual‑hook handling. Parallel or tandem lifts accelerate assembly and repair tasks, cutting vessel dock time.

4. Specialty Fabrication

In industries such as wind‑turbine manufacturing and heavy machinery production, dual‑hook cranes support parallel handling of large castings and machined parts, streamlining work flows and reducing manual rigging effort.

5. Precision Assembly Lines

Automotive and railcar assembly lines benefit from tandem lifts of chassis or sub‑assemblies. Coordinated hook movement ensures precise placement, improving throughput and reducing scrap rates.

FAQs

Q: Can the hooks operate at different heights?
A: Yes. Our system allows height differentials up to 4 meters via independent drum controls.

Q: What's the lead time for a custom 25-ton dual-hook crane?
A: 14–18 weeks, including design validation, material procurement, and FAT (Factory Acceptance Testing).

Maintenance and Lifecycle Management

Preventive Maintenance Schedule

Component Lifespan

• Wire Ropes: 8–12 years (with proper lubrication and <10% broken wires).

• Hooks: 15–20 years (if annual MPI shows no cracks).

• Electronics: 10–15 years (subject to environmental conditions).

How to get quotation?

Send us your RFQ including the parameters above, we will reply our quotation accordingly.