5 Ton Electric Single Overhead Crane

1. Bridge Structure

This is the main traveling frame of the crane that spans the width of the bay.

Single Girder (Main Beam): A single, fabricated steel box beam that supports the hoist and trolley. For a 12-ton capacity, this beam is designed and sized to handle the load with a significant safety factor, preventing excessive deflection.

End Trucks: The rigid steel housings located at each end of the bridge girder. They contain the wheels, bearings, and axles that allow the entire crane to travel along the runway rails.

Bridge Wheels: The wheels mounted on the end trucks that support the entire crane and load. A single girder crane typically has four bridge wheels (two per end truck).

Bridge Drive Unit: The motor, brake, and gearbox assembly that powers the bridge wheels. For a 12-ton crane, this is usually a dual-drive system, meaning there is a drive unit on both end trucks for synchronized and positive movement.

Bridge Conductor System: How the crane receives power for travel. Common types include:

Festoon System: A series of cables and carriers that fold and unfold as the crane moves.

Enclosed Conductor Bar (Bus Bar): A rigid, insulated bar system with copper conductors that a collector system slides along. Often preferred for heavier-duty applications and longer spans.

2. Hoist and Trolley Unit

This is the mechanism that raises, lowers, and moves the load laterally across the length of the bridge girder.

Hoist Motor: The electric motor that provides the power to lift and lower the load. It is designed for heavy-duty, intermittent operation.

Hoist Gearbox: Reduces the high speed of the motor to a usable, powerful speed for lifting heavy loads.

Braking System: Multiple brakes are critical for safety.

Primary Holding Brake: An automatic, spring-set, electrically released brake located on the motor shaft. It engages immediately if power is lost, holding the load.

Secondary (Emergency) Brake: A mechanical load brake often located within the gearbox for added safety.

Regenerative Lowering Brake: The electric control system itself provides braking by controlling the speed during lowering.

Drum or Sheave Assembly: For wire rope hoists, this is a grooved drum around which the wire rope winds. For chain hoists, this is a set of sheaves (pulleys) that guide the load chain.

Wire Rope / Load Chain: The flexible element that connects to the load.

Wire Rope: More common for capacities of 12 tons. It is reeved through a set of sheaves on the hoist and hook block to provide mechanical advantage.

Load Chain: (Less common for 12-ton single girder, but possible). A welded alloy chain used for lifting.

Hook Block: The assembly that holds the hook and the sheaves. The number of sheaves (reeving) determines the mechanical advantage (e.g., 4 parts of line to lift 12 tons with a 3-ton line pull hoist).

Lifting Hook: The forged steel hook that holds the load. It is equipped with a safety latch to prevent the sling from accidentally disengaging.

3. Trolley Frame

The frame that houses the hoist and allows it to travel along the bottom flange of the bridge girder.

Trolley Drive Motor: A smaller motor that powers the trolley wheels for cross-travel motion.

Trolley Wheels: The wheels that run along the bottom flange of the bridge girder.

4. Electrical Control System

The "nervous system" of the crane.

Operator Control: How the crane is commanded.

Pendant Control: The most common method. An operator uses a suspended push-button station (pendant) on a cable to control all crane functions (Hoist Up/Down, Bridge Left/Right, Trolley Forward/Back).

Radio Remote Control: An increasingly popular option where the operator uses a wireless transmitter, allowing for greater mobility and safety.

Cab Control: Less common for single girder cranes; the operator controls from a mounted cab on the crane.

Control Panel / Panel Box: Contains the contactors, overload relays, variable frequency drives (VFDs), and power supplies that manage the electricity to the motors.

Variable Frequency Drives (VFDs): Often used on modern 12-ton cranes for precise control of speed and acceleration for both hoisting and traveling motions. This prevents load swing and provides smoother, safer operation.

Limit Switches: Critical safety devices that automatically cut power to prevent overtravel.

Hoist Upper Limit Switch: Prevents overwinding and the hook from hitting the hoist itself.

Hoist Lower Limit Switch: Prevents the rope from becoming completely slack or the hook block from crashing.

End Limit Switches: Stop the bridge and trolley before they reach the very end of their runway tracks.

5. Runway System

This is the fixed infrastructure that the crane travels on. It is not part of the crane itself but is essential for its operation.

Runway Beams: Typically wide-flange (I-beams) or fabricated box beams that are securely mounted to the building structure.

Runway Rails: The steel rails (often ASCE rail or crane rail) mounted on top of the runway beams that the bridge wheels run on. They provide a smooth, hard wearing surface.

Rail Clips / Anchors: Secure the rails to the runway beams.

Runway Conductors: The extended power system that runs the length of the bay, to which the bridge conductor system connects.

.

Electrical & Control Components

These parts provide power and command the crane's functions.

Power Delivery System:

Festoon System: The most common method. A series of cables (for power and control) are carried in a flexible tray that extends and retracts with the crane's movement.

Conductor Bar System (Enclosed Track): A rigid, insulated bar system mounted along the runway. Collector shoes on the crane slide along this bar to draw power. Preferred for longer distances, higher duty cycles, or harsh environments.

6. Safety Devices

Bumpers: Rubber or spring-loaded buffers on the end trucks and trolley to absorb energy in the event of a minor collision with the end stops.

Anemometer (Optional): For cranes installed outdoors, a wind speed meter will disable crane operation if wind speeds become dangerously high.

Warning Devices: A horn or beacon to alert personnel that the crane is in motion.

Sketch

Main technical

1. Cost-Effectiveness

Lower Initial Investment: This is one of the biggest advantages. The design requires less material (one girder instead of two) and a simpler structure, making it significantly less expensive to purchase and install than a double girder crane of the same capacity.

Reduced Support Structure Costs: Because the crane itself is lighter, the building support structure (runway beams and columns) can often be less robust, leading to further savings in construction or modification costs.

2. Ideal for Lower Headroom Facilities

The hoist is mounted directly on the bottom flange of the girder, not between two girders. This creates a lower hook approach-the distance from the runway beam to the hook is minimized. This is a critical advantage in buildings with limited vertical space, allowing you to maximize lift height.

3. Lightweight and Efficient Design

The single girder design makes the entire crane bridge lighter. This reduces the load on the building's structure and can lead to energy savings as the bridge drive motors require less power to move the crane.

4. Simplicity and Reliability

With a simpler mechanical structure (one girder, one hoist), there are fewer components that can fail. This translates to easier maintenance, reduced downtime, and generally high reliability for standard lifting applications.

5. Ease of Installation and Relocation

The components are lighter and often easier to assemble than those of a double girder crane. This can shorten installation time and reduce labor costs. If you need to move the crane to a new location in the future, the process is generally simpler.

6. Perfect for Moderate Duty and Speeds

A 12-ton single girder crane is excellently suited for applications that require frequent but not severe-duty lifting. They are ideal for:

Workshops and fabrication shops

Manufacturing assembly lines

Warehouses and storage facilities

Loading bays

Maintenance bays

They operate efficiently at standard hoisting and travel speeds, which are perfectly adequate for most industrial tasks.

7. Customization and Flexibility

These cranes are highly adaptable. They can be configured in various ways:

Top-Running: The crane rides on rails mounted on top of the runway beams. This is the most common configuration and provides the greatest hook height.

Under-Running (Underhung): The crane wheels ride on the bottom flange of the runway beams, which are typically supported by the roof structure. This allows for a system where multiple cranes can operate on the same runway system and be interchanged.

Primary Applications and Use Cases

This crane is a workhorse in industries where reliable, repeated lifting of heavy materials is a core part of the operation.

1. Manufacturing & Assembly Plants:

Machine Shops: Moving raw material (steel plates, bars), positioning heavy parts on CNC machines, lathes, and mills, and handling finished components.

Automotive Manufacturing: Handling engine blocks, transmissions, vehicle frames, and large sub-assemblies along production lines.

Heavy Equipment Manufacturing: Assembling and moving large sections of agricultural, construction, and mining machinery.

Appliance Manufacturing: Moving and positioning heavy industrial appliances like commercial refrigerators, industrial washers, and large metal stampings.

2. Warehousing & Logistics:

Heavy Goods Storage: Loading and unloading heavy palletized goods, industrial machinery, and large containers from trucks and positioning them in storage racks. Ideal for warehouses storing metal products, machinery, or heavy building materials.

Distribution Centers: For facilities that handle large, dense products beyond the capacity of standard forklifts.

3. Metalworking & Fabrication:

Steel Service Centers: Handling coils of steel, sheets, and plates. Often used in conjunction with below-the-hook attachments like coil grabs or sheet lifters.

Fabrication Shops: Moving welded structures, I-beams, and large fabricated parts between workstations (cutting, welding, grinding, painting).

Foundries: Handling molds, cores, and castings after they have cooled.

4. Construction Material Supply:

Lumber Yards: Handling large bundles of lumber and engineered wood products.

Building Material Suppliers: Moving heavy bags of cement, pallets of bricks, blocks, and large stone slabs.

Pre-cast Concrete Facilities: Lifting and turning large pre-cast concrete panels, beams, and septic tanks.

5. Maintenance, Repair, & Overhaul (MRO) Facilities:

Power Generation: Lifting large pumps, motors, turbines, and transformers for maintenance.

Aviation MRO: Removing and installing aircraft engines and other major components.

General Industrial Maintenance: Essential for safely removing heavy machinery for repair, facilitating plant upgrades, and performing equipment servicing.

6. Recycling and Waste Management Facilities:

Scrap Yards: Handling large bales of scrap metal and non-ferrous materials.

Waste Transfer Stations: Moving large containers and compactors.

Phase 1: Design, Engineering, and Planning

Customer Requirements Analysis:

Review technical specifications: Capacity (12-ton), span, lifting height, duty class (e.g., FEM 1Am, ISO M4), operating environment, voltage, and control requirements.

Confirm runway details (existing or new) including rail type, gauge, and end stops.

Technical Design & Calculation:

Structural Design: Engineers design the main single girder (usually a rolled or welded I-beam or box girder) using CAD software. Finite Element Analysis (FEA) is performed to ensure rigidity and deflection are within standards (e.g., CMAA, FEM).

Load & Stress Calculations: Calculate maximum stress, deflection (typically limited to Span/500 for single girder), and fatigue life.

Mechanical Design: Select and design the end carriages (trucks) with wheels, drive mechanisms, and bumpers. Design the hoist trolley travel system.

Electrical Design: Create schematics for the power supply (e.g., festoon or conductor bar system), control circuits, and safety devices.

Bill of Materials (BOM): Generate a complete list of all raw materials, purchased components (hoist, motor, gearbox, brakes, wheels, electrical components), and standard parts.

Procurement:

Order raw materials (steel plates, beams, etc.) as per the BOM.

Source and purchase certified components:

Electric Wire Rope Hoist: 12-ton capacity with appropriate lifting speed and hook approach.

End Carriage Drive Units: Motors, gearboxes, brakes, and wheels.

Electrical Components: Control panel, pendant station (or radio control), limit switches, festoon system, motors, and cables.

Phase 2: Manufacturing and Assembly
4. Fabrication of Main Components:
* Main Girder Fabrication:
* Cutting: Steel plates are cut to size using CNC plasma or laser cutting machines.
* Welding: Components are jigged and welded by certified welders using Submerged Arc Welding (SAW) or Gas Metal Arc Welding (GMAW/MIG) for high-strength, distortion-controlled welds.
* Machining: Drilling and machining of connection points for end carriages and trolley rails to ensure precision.
* End Carriage Fabrication: Fabrication of the two end carriages that will support the girder and house the wheels and drives.

Surface Preparation and Painting:

Blasting: All structural components are shot blasted to SA 2.5 standard to remove rust, mill scale, and create a surface profile for paint adhesion.

Priming: Application of a high-quality anti-corrosion primer.

Painting: Application of topcoat paint in specified color and thickness. This is often done in a controlled paint booth.

Mechanical Assembly:

End Carriage Assembly: Mount wheels, drive units (motors and gearboxes), and brakes onto the fabricated end carriages.

Girder and End Carriage Marriage: Lift the main girder and securely bolt it to the two end carriages. The alignment is critical to prevent runway wheel scrubbing.

Trolley Rail Installation: Install the running rail for the hoist trolley on the bottom flange of the main girder.

Hoist Trolley Assembly: Assemble the trolley frame and mount it on the girder rail. Alternatively, the complete pre-assembled hoist is often attached directly to a trolley frame.

Electrical Assembly:

Cable Festoon/Conductor Bar System: Install along the length of the bridge girder.

Wiring: Run and secure all cables for bridge travel, trolley travel (if applicable), and hoist functions through cable trays and conduits.

Control Panel: Mount and wire the main control panel, including contactors, overload protectors, and programmable logic controller (PLC) if used.

Limit Switches and Safety Devices: Install and set up end limit switches for bridge travel, upper limit switch for the hoist, and emergency stop buttons.

Pendant Station: Wire the pendant control station with clearly labeled buttons for Up/Down, East/West, and emergency stop.

Phase 3: Testing, Inspection, and Quality Control
8. Factory Acceptance Testing (FAT):
* Visual Inspection: Check all welds, bolts, mechanical parts, and paintwork for quality.
* No-Load Test: Run the crane in all directions (bridge long travel, hoist up/down) to check for smooth operation, unusual noises, and proper alignment.
* Load Test (The Most Critical Step):
* Static Load Test: Lift a test load of 15 tons (125% of rated capacity) and hold it at a safe height. Inspect for deformations, cracks, or any permanent deflection.
* Dynamic Load Test: Lift a test load of 12 tons (100% of rated capacity) and run the crane through all its functions-traveling, hoisting, and lowering. Check performance, braking, and safety functions under load.
* Functionality Tests: Verify all limit switches, emergency stops, and control functions operate correctly.
* Electrical Tests: Check insulation resistance, earth continuity, and voltage.

Dismantling & Preparation for Shipment:

Once testing is passed, the crane is partially disassembled for safe and efficient shipping.

The bridge is typically separated from the end carriages.

All components are carefully packed, crated, and protected against damage during transit.

Documentation Pack is prepared, including: Test Certificates, Load Test Report, Assembly Drawings, Electrical Diagrams, Parts List, and Operation & Maintenance Manuals.

Phase 4: Installation and Commissioning (On-Site)
10. Site Installation:
* Delivery of components to the customer's facility.
* Assembly of the end carriages and main girder on the runway rails.
* Electrical connection to the main power supply and final wiring.
* Installation of the pendant station.

Final On-Site Testing & Commissioning:

Repeat a full No-Load and Load Test on the actual runway to ensure everything performs correctly in its final environment.

Train the customer's operators and maintenance personnel on safe operation and basic troubleshooting.

Hand over all documentation and obtain customer sign-off.

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%.