Electromagnetic Overhead Cranes with Spreader Beam

QL electromagnetic overhead cranes' magnet beam can be mounted either parallel or perpendicular to the main girders. The lifting beam carries several electromagnets whose combined pull attaches to long ferrous loads, enabling efficient handling of wide, heavy loads that would be difficult to move with a single hook. Yuantai's QL bridge cranes cover capacities from 5+5 tons up to 50+50 tons (e.g. 10+10t, 20+20t, etc.), spans of about 10.5–31.5m, and lift heights 6–18m. They are rated for work classes A5–A7, and their lifting capacities include the weight of the magnet beam and magnets. In operation, power to the magnets is switched on/off to pick up/release steel, and many models can switch to permanent-magnet mode for energy-saving load holding if equipped with a power-failure back-up system.

Beam Types and Configurations

1. Parallel vs. Perpendicular Beams

Electromagnetic Spreader Beam Perpendicular to the Main Girder

Electromagnetic Spreader Beam Parallel to the Main Girder

The magnet beam can be mounted parallel to the main bridge girders or perpendicular to them, depending on the application. A parallel beam (mounted lengthwise) is common when the long dimension of loads aligns with the crane span. A perpendicular (90°) beam is used when materials run across the span. Yuantai's QL electromagnetic overhead cranes offer both options.

2. Fixed vs. Rotating Beams

Some magnet-beam cranes have beams that are fixed, while others use rotating beams. A rotating beam (either upper-rotating or lower-rotating design) is mounted on a turntable so the load can be rotated horizontally under the crane. Rotating beams are used when steel slabs or long bars must be turned horizontally during handling (for instance, to align different orientations of plates). Rotation angles of 90°, 180°, or 360° can be specified. Telescoping (extendable) magnet beams are also available: these let you adjust the beam length to match various load sizes.

3. Custom Options

Ultra-long beams and split beams for extremely wide slabs (e.g. width ≤4200mm, length ≤46000mm) can be built. Telescoping beams include hydraulic adjustment and ensure even lift force even on very long plates. The design can also include features like speed regulation for beam rotation (e.g. 1:10 reduction), overload alarms, remote control, PLC logic with diagnostics/display, etc. – all to meet the needs of demanding steel-handling environments.

Telescopic Electromagnetic Spreader Beam

Overhead Crane with a Top-rotating Electromagnetic Spreader Beam

Overhead Crane with a Bottom-rotating Electromagnetic Spreader Beam

Magnet Configuration and Capacity

1. Multiple Magnets

A electromagnetic overhead cranes with spreader Beam's lifting beam carries multiple electromagnets arranged along its length. Typically, two or more disc magnets (often rectangular pole faces) are hung beneath the beam. Customers can choose the number, size, and arrangement of magnets to match the load. Magnets can be rectangular (wide flat pole face) for lifting large plate bundles, or circular (disk) magnets for picking up coils or bundled rods. Each magnet has an open or covered pole surface and is powered by a dedicated hoist transformer. The lifting capacity of the crane includes the weight of the spreader beam. For safety, the working load must account for the magnets' own weight and any attachments (e.g. suspension shackles).

2. Force Distribution

Because the beam spans under the trolley, the load is spread across multiple pickup points. This reduces stress on individual magnets and on the rope/sheave compared to a single magnet. In practice, the payload is often a few percent less than the rated sum due to dynamic effects and magnet seating. (The net material weight is therefore slightly below rated). Key design factors include pole-face length, magnet pull rating, and beam deflection under load. The magnets must be evenly matched and all poles must fully contact the steel – any air gap or surface rust reduces effective pull. In our experience, during operations, if operators remove severe rust or dirt from the surface of the load, this helps ensure optimal contact between the electromagnet and the steel material, thereby helping to ensure operational safety.

Suitable Materials and Applications

Electromagnetic overhead cranes with spreader beam excel at handling long, flat ferrous loads. Common applications include:

Steel Plates

Handle wide bundles of steel plates, including plates 1–20 mm thick and several meters long. Multiple magnets on a beam can lift several plates at once, depending on the load and magnet configuration.

Sections and Beams

Lift H-beams, I-beams and other long steel sections. A magnet beam with a suitable magnet layout can handle steel bundles without individual hooks or clamps.

Steel Billets and Blooms

Move steel billets and blooms from casting and rolling processes. A suitably designed magnet beam can lift multiple pieces in one operation when their size and weight allow.

Steel Bars and Rods

Handle bundles of rebar and round steel bars. The number and spacing of magnets can be selected to suit the bundle length and lifting requirements.

Coils and Cylinders

Lift suitable steel coils and cylindrical steel products using magnets designed for their shape, contact area and weight. The magnet configuration must match the load.

Composite Loads

Handle different types of steel products with a suitable magnet-beam arrangement. Mixed loads require a compatible magnet layout and a verified lifting plan.

Design and Safety Considerations

1. Crane Structure

QL electromagnetic overhead cranes with Magnet Beam use double-girder welded box girders (for rigidity under heavy loads) with end beams of high-strength steel. All main welds meet or exceed national standards. The beam and trolley are designed for steel mill environments (ambient -25℃ to +40℃). Wheels are forged cast iron, quenched and rolled to minimize wear. The entire crane is finished with three layers of durable paint for corrosion resistance. End carriages use robust motors and disc brakes (often high-quality planetary gear reducers) to achieve the required speeds and duties (up to A7).

2. Suspension & Center-of-Gravity

The magnet beam itself is suspended from the trolley by heavy-duty brackets or turntables, ensuring it hangs level under gravity. If rotation is enabled, bearings allow smooth pivoting. The beam and magnets are designed so that, when lifting a load, the system's center of gravity is under the trolley for stability. Designers perform calculations to ensure uneven load or rotation does not overload one side. Typically, multiple lift points on the beam minimize torque on the structure. For very long beams, deflection is controlled by choosing appropriate section modulus (moment of inertia) and sometimes adding stiffeners.

3. Safety Features

QL cranes include all standard safety devices: travel limit switches, double-limit hoist limiters, anti-collision and anti-sway features, and emergency stops. Crucially for magnets, many systems include power-failure backup (e.g. a battery or permanent magnet mode) that holds the load if supply is lost. Alarm systems warn of over-current or overheating in the magnets. Operators must still follow proper procedures: never allow an energized magnet to idle in contact with thin steel (to avoid overheating), and always lock any hook or spreader when not lifting. Yuantai's design notes specifically caution that the hook's swivel joint must be locked (using set screws) to prevent rotation of the hook, which could otherwise turn the magnet beam unexpectedly. We also adhere to international machinery safety standards (CE Machinery Directive) and relevant FEM and ISO crane design rules.

Selecting and Sizing Your Electromagnetic Overhead Cranes with Spreader Beam

To choose the right magnet-beam crane, consider the following factors:

1. Load specifications

Determine the dimensions (length, width, thickness) and weight of the heaviest bundles or items to be lifted. Include any packaging or blocking weight. Remember to count the magnet beam's own weight when calculating the required capacity.

2. Magnet type and number

Based on the steel surface shape (plate vs. profile vs. scrap), choose magnet geometries (flat rectangular vs. circular). Calculate needed pull: e.g. a steel slab might require 0.1–0.3N/ mm² of magnetic pull per unit area; adjust magnet size and number accordingly. For very wide loads, use multiple magnets spaced to cover the area. If loads are of mixed type, consider a modular beam that can be reconfigured with more or fewer magnets.

3. Beam span and length

Match the beam length to load length. For long plate bundles, a long beam ensures full coverage. For narrow profiles, a shorter beam may suffice. Yuantai can supply telescoping design to adapt to varying lengths.

4. Rotation needs

Do you need to rotate loads? If plates or sections must be turned during handling or assembly, specify a rotating beam crane. If rotation is not needed, a fixed beam is simpler.

5. Duty cycle and height

Higher work classes (A6–A7) allow faster lifts and frequent use. Lifting height depends on warehouse or shop height. Longer spans and higher lifts may require more powerful hoists and larger wheels.

Technical Specifications

The table below shows a sample specification for a 10+10t QL magnet-beam crane (span variants 10.5–31.5m).

The specifications table above provides reference parameters only for lifting capacities of 10+10 metric tons or more. We tailor each crane's parameters (motor sizes, wheel design, etc.) to the chosen capacity and span. For very long spans or wide loads, we calculate the max. wheel load and recommend appropriate track (e.g. rail type QU70 or P43). All structural dimensions and wheel profiles meet ISO 12480 and related standards.

Design & Manufacturing Standards

Yuantai's electromagnetic overhead cranes with spreader beam are engineered to international and national crane standards. Design and fabrication follow relevant codes such as: European FEM/ISO (e.g. FEM 1.001 FEM guidelines for cranes), EN 15011 (bridge cranes safety), as well as Chinese GB standards (GB/T 3811, GB 6067, etc.) for structural and safety requirements. The electrical system uses SIEMENS/Schneider components and complies with IEC 60204-1 for electrical safety. Welding of the girders is done to ISO 9606 (welding procedures approved) and all welds are X-ray inspected. Each crane undergoes full load testing (lifting 125% of rated load) before shipment, and we provide CE and other certificates per customer region.

FAQs

Q: How do I know if I need a rotating beam or a fixed beam?
A: If your operations require rotating loads (e.g. turning plates or sections through 90–360°), then a rotating magnet beam crane is appropriate. Otherwise, a fixed (non-rotating) magnet beam is simpler and more cost-effective. Yuantai offers both upper- and lower-rotating designs, and we can advise based on your layout and material flow.

Q: Can the magnets handle rust or uneven plates?
A: Yes, we use flat magnets with specialized pole shoes to improve contact on slightly irregular or rusty steel surfaces. However, for maximum hold, operators should ensure surfaces are reasonably clean. Slight gaps reduce force, so heavy scale/dust should be removed. The magnet beam spreads multiple magnets across the load, so minor unevenness in one area is compensated by neighboring magnets.

Q: What if power fails during a lift?
A: All our crane magnets can be equipped with power-off emergency retention. In an electromagnet, this is done by engaging a permanent-magnet circuit (or backup battery) when power is lost, preventing sudden drop of the load. The operator then lowers or safely lands the load using stored power or clutch.

Q: Are these cranes hard to maintain?
A: On the contrary, they are designed for easy service. The double-girder structure is bolted for convenient inspection access. Motors and controls use standard parts (SIEMENS, Schneider, etc.), and the magnets are modular (we can supply spares easily). Regular maintenance is similar to any industrial EOT crane: greasing, brake checks, rope inspection, and electrical testing.

Q: How do I choose between Yuantai's QC and QL cranes?
A: QC-series cranes carry a single lifting magnet (used like a giant hook), suitable for general steel sheet and scrap handling. QL-series magnet-beam cranes use a long beam with multiple magnets, ideal when you need to lift long, wide loads (like bundles of plate or bars) in one go. If your loads are very long or require horizontal rotation, QL is the better choice; for small batches or simple lifts, QC might suffice.