Tension Load Cells for Crane Scales and Lifting

A tension load cell measures tensile or pulling force and is widely used in crane scales, suspended weighing, lifting equipment, load monitoring, and industrial force measurement.

Different lifting and weighing applications require different load-cell technologies. Common options include tension load cells, S-type load cells, load pins, shackle load cells, load links, crane scale load cells, and wireless load monitoring systems.

Each design offers different mechanical and installation advantages. The right choice depends on factors such as load direction, rated capacity, accuracy, mounting arrangement, environmental conditions, side loads, shock loading, and required monitoring method.

Crane and lifting applications are safety-critical, so load-cell selection should never be based on rated capacity alone. The complete lifting arrangement, applicable safety requirements, manufacturer specifications, and installation conditions should be evaluated before selecting a load cell.

What Is a Tension Load Cell?

A tension load cell is a force sensor designed to measure a pulling or tensile force. It is commonly used where a load is suspended from, pulled by, or connected to the load cell.

How Does a Tension Load Cell Work?

A tension load cell converts mechanical pulling force into an electrical signal:

Applied Tension → Elastic Deformation → Strain Gauges → Electrical Signal → Weight/Force Display

When tension is applied, the load cell’s elastic sensing element deforms slightly. Strain gauges attached to the sensing element detect this deformation and change resistance.

The strain gauges are typically connected in a Wheatstone bridge circuit. The resulting electrical output is a small signal, commonly specified in mV/V. Signal-conditioning electronics then amplify and process the signal so an indicator, controller, PLC, or other measurement system can display the corresponding force or weight.

Where Are Tension Load Cells Used?

Tension load cells are suitable for applications where force is applied in a pulling direction, including:

• Crane scales for suspended load weighing
• Hoists and lifting equipment for load monitoring
• Suspended weighing systems
• Cable tension measurement
• Material handling equipment
• Force testing and test equipment
• Load monitoring in lifting and industrial systems

The correct tension load cell should be selected based on the working load, safety requirements, load direction, environmental conditions, mechanical connections, and required accuracy, not rated capacity alone.

What Load Cell Is Used in a Crane Scale?

A crane scale can use different load-cell designs depending on how the load is suspended and how force is transferred through the lifting equipment. Common options include tension load cells, shackle load cells, load links, and load pins.

Tension Load Cells

Tension load cells are designed to measure pulling or tensile forces directly. They are suitable for suspended weighing applications where the load cell is installed in the load path between lifting components.

They can provide accurate force measurement when the load is applied in the intended direction and the mechanical arrangement is properly designed.

Shackle Load Cells

A shackle load cell combines load measurement with a shackle-style lifting connection. It is commonly used where the load needs to be measured directly through a lifting point.

Typical applications include:

• Heavy lifting
• Load monitoring
• Temporary weighing
• Suspended loads

Their robust construction makes them suitable for demanding lifting and material-handling applications, subject to the manufacturer’s rated capacity and safety requirements.

Load Links

Load links measure tensile force between two lifting connections. They are installed directly in the load path and can be used for suspended weighing, crane monitoring, and lifting-force measurement.

Load links are particularly useful when the application requires a compact connection between lifting components while continuously monitoring the applied force.

Load Pins

A load pin is designed to replace a conventional structural pin while measuring the force transferred through the connection. Strain gauges inside the load pin detect deformation caused by the applied load.

Load pins can be used in cranes, hoists, sheaves, lifting mechanisms, and other engineered connections where replacing an existing pin with a force-measuring pin is practical.

Tension Load Cell vs Load Pin vs Shackle Load Cell

Tension load cells, load pins, shackle load cells, and load links all measure force, but they are designed for different mechanical arrangements. The correct choice depends mainly on how the load is transferred through the lifting system.

Choosing the Right Design

A tension load cell is suitable when the sensor can be installed directly in the tensile load path. A load pin is useful when an existing structural pin can be replaced with a force-measuring pin.

A shackle load cell is suitable when measurement needs to be integrated into a shackle-style lifting connection, while a load link provides a compact solution for measuring tensile forces between lifting points.

How to Choose a Tension Load Cell for Crane Applications

Choosing the right tension load cell for crane applications depends on capacity, force direction, mechanical connection, environment, and system compatibility. See LCS-11: How to Choose the Right Load Cell for general selection guidance.

Rated Capacity

Consider the maximum lifted load, dead load, dynamic loading, load direction, and safety requirements. Do not select a load cell based only on crane capacity; shock loads and uneven loading can increase the actual force.

Tension vs Compression

A tension load cell measures pulling force, while a compression load cell measures pushing or downward force. The sensor must match the actual force direction to ensure reliable measurement and safe operation.

Mechanical Connection

Check compatibility with shackles, hooks, pins, clevises, load links, and mounting points. Proper alignment is important because side loads, bending, or twisting can affect accuracy and damage the sensor.

Environment

For outdoor cranes, consider rain, dust, salt, moisture, chemicals, corrosion, and temperature changes. Check the load cell’s sealing, construction materials, cable protection, and environmental rating.

Output and Integration

Choose an output compatible with the weighing system, such as analogue mV/V, digital output, or wireless load monitoring. The load cell may connect to a crane display, data logger, or PLC/control system where appropriate.

For safety-critical crane applications, always consider the complete load path and follow the load-cell manufacturer’s installation and safety requirements.

Load Cell Capacity, WLL and Safety Factor

For crane and lifting applications, load cell capacity, Working Load Limit (WLL), and breaking load are not the same thing. A load cell’s rated capacity describes its measurement range, while WLL defines the permitted working load of a lifting component. Breaking load is associated with failure and must never be treated as a normal operating limit.

What Is Working Load Limit (WLL)?

Working Load Limit (WLL) is the maximum load a lifting component is permitted to support during normal operation under specified conditions. It applies to components such as shackles, hooks, lifting links, slings, and other lifting equipment.

WLL should be determined according to the component’s design, application, applicable requirements, and manufacturer specifications. It is not simply the same as the load cell’s rated capacity.

Load Cell Rated Capacity

Load cell rated capacity is the maximum force or weight range the sensor is designed to measure while operating within its specified performance limits.

For example, a 10-ton tension load cell is designed to measure loads up to its specified rated capacity. This does not automatically mean that every lifting component connected to it has a 10-ton WLL.

Breaking Load / Ultimate Load

Breaking load or ultimate load refers to a load associated with structural failure or the maximum load a component can withstand before failure under defined test conditions.

It must never be used as the allowable working load. Operating a crane or lifting system close to its failure load creates unacceptable safety risks.

Safety Factor

The safety factor provides a margin between the permitted working load and a component’s failure-related capacity. The required factor depends on the type of lifting equipment, application, applicable standards, operating conditions, and manufacturer specifications.

For crane applications, safety factors should be considered for the complete load path, including the load cell, shackles, hooks, pins, lifting attachments, and supporting structure.

Dynamic Loading in Crane and Lifting Applications

The force measured by a crane load cell can temporarily exceed the static weight of a suspended load. Starting, stopping, acceleration, shock, and sudden changes in load movement can create additional dynamic forces in the lifting system.

Common sources include sudden lifting, load acceleration, starting and stopping, shock loading, load swinging, snagging, and impact. These forces can affect the load cell, hooks, shackles, pins, lifting attachments, and crane structure.

Static Load vs Dynamic Load

A static load is the weight of a load when it is suspended without significant movement. For example, a suspended load may weigh 2,000 kg under static conditions.

During lifting or lowering, however, acceleration or shock loading can temporarily increase the force experienced by the lifting system. The load-cell selection therefore needs to account for the expected dynamic conditions rather than considering only the static weight.

The appropriate dynamic factor should be determined from the equipment design, application conditions, applicable requirements, and manufacturer or engineering specifications. There is no single universal factor that should be applied to every crane or lifting application.

What Is a Load Pin?

A load pin is a force-sensing structural pin that can replace a conventional pin in suitable machinery. It measures the force transferred through the pin and converts that force into an electrical signal for a monitoring, weighing, or control system.

Load pins typically use strain gauges built into the sensing element. When a load is applied, the pin experiences controlled deformation, allowing the strain gauges to measure the force. This makes the load pin part of the mechanical load path rather than a separate sensor mounted alongside it.

Where Are Load Pins Used?

Load pins are commonly used where existing machinery already relies on structural pins or pivot connections. Typical applications include:

• Crane sheaves and pulley assemblies
• Winches and lifting equipment
• Clevis connections and pinned joints
• Lifting mechanisms
• Structural pivot points
• Material-handling equipment

Advantages of Load Pins

Load pins can provide several practical advantages in engineered lifting and force-measurement systems:

• Compact integration: The sensor can replace an existing structural pin where the design permits.
• Reduced installation changes: Less modification may be required compared with adding a separate load cell.
• Direct measurement: Force is measured directly through an important point in the load path.
• Custom dimensions: Load pins can be manufactured to suit specific diameters, lengths, mounting arrangements, and load requirements.

Load pins are particularly useful when space is limited or when modifying the existing mechanical arrangement would be difficult. However, correct sizing, installation, alignment, load direction, and safety requirements must be verified for the specific application.

How Does a Shackle Load Cell Work?

A shackle load cell measures tensile force through a load-bearing shackle connection and converts the applied force into an electrical signal for weighing or load monitoring.

The basic measurement process is:

Load → Shackle/Load Cell Body → Strain Measurement → Electrical Output

When a suspended load is applied, tensile force passes through the shackle load cell and causes a small, controlled deformation in its sensing element. Internal strain gauges detect this deformation and generate an electrical signal proportional to the applied force.

Tensile Force Measurement

Shackle load cells are designed for tensile or pulling-force measurement. They are commonly used for suspended loads, crane monitoring, lifting equipment, and force measurement where the load passes through a shackle connection.

Shackle Connection

The load cell must be correctly matched to the shackle, pin, load rating, dimensions, and connection arrangement. The pin must fit correctly, and the load should remain aligned with the intended load path. Incorrect pins, incompatible shackles, side loading, or misalignment can affect accuracy and create safety risks.

Display and Wireless Monitoring

The electrical output can be connected to a crane display, weighing indicator, data logger, or monitoring system. Wireless shackle load cells can transmit measured load data to a remote display or monitoring device, which is useful where cables would restrict movement.

Load Monitoring

Shackle load cells provide real-time information about the force applied to a lifting connection. They can be used for load monitoring, overload indication, lifting verification, and recording load data, depending on the system design.

For lifting applications, always verify the load cell, shackle, pin, connection hardware, and complete load path are compatible and suitable for the intended working conditions.

Do Crane Load Cells Need Certification?

Crane load cells do not all require the same certification. Requirements depend on the application, jurisdiction, lifting equipment, intended use, applicable standards, site requirements, and manufacturer specifications. Additional requirements may apply when the measured weight is used for trade or commercial transactions.

For lifting applications, the requirements should be assessed for the complete lifting and measurement system, rather than assuming that a particular load cell certificate alone establishes compliance.

Calibration and Certification Are Not the Same

These terms describe different activities:

Calibration → Measurement Verification → Certification/Compliance Documentation

• Calibration checks the load cell or weighing system against a known reference and documents its measurement performance.
• Measurement verification determines whether the equipment performs within specified or permitted limits for its intended application.
• Certification or compliance documentation provides evidence that applicable requirements, standards, or customer/site specifications have been met.

A calibration certificate therefore does not automatically mean that a crane or lifting system is certified for every application.

Australian Standards and Good Practice

In Australia, crane and lifting applications should be assessed against the applicable Australian Standards, regulatory requirements, manufacturer instructions, and site procedures. The AS 2550 series provides guidance for the safe use of cranes, hoists, and winches.

Where weighing is used for trade or commercial purposes, additional measurement requirements may apply. The National Measurement Institute (NMI) states that instruments used for trade must be verified by appropriately registered verifiers under the relevant measurement requirements.

Industry guidance such as LEEA good practice can also help inform lifting-equipment selection, inspection, and safe-use procedures. However, LEEA guidance or membership should not be treated as an automatic certification of a particular load cell or lifting system.

For a specific crane application, confirm the required certification, calibration, testing, and documentation with the equipment manufacturer, competent lifting professional, site requirements, and relevant Australian regulatory authority.

Calibration and Proof Testing of Crane Load Cells

Calibration and testing are important before a crane load cell is used for safety-critical weighing or load monitoring. Testing helps identify measurement errors, mechanical problems, or damage that could affect load readings.

Key checks can include:

• Zero check: Confirm the system returns to the expected zero reading when unloaded.
• Known-load testing: Apply a suitable reference load and compare the indicated value with the expected result.
• Repeatability: Check whether repeated measurements under the same conditions produce consistent readings.
• Capacity verification: Confirm the load cell and complete measurement system are suitable for the intended operating range.
• Visual inspection: Check the load cell body, pins, shackles, cables, connectors, and mounting points for damage, corrosion, deformation, or other issues.
• Calibration documentation: Record test results, calibration data, equipment identification, and any adjustments or observations.

Proof Load Testing

Proof load testing is different from ordinary calibration. Calibration evaluates measurement performance against a known reference, while proof testing is concerned with demonstrating that equipment or a lifting component can withstand a specified test load under defined conditions.

Proof testing should be performed only according to the applicable equipment requirements, manufacturer specifications, engineering procedures, and relevant standards. The appropriate test load and procedure are not universal and should not be assumed from the load cell’s rated capacity alone.

Common Problems With Crane and Tension Load Cells

Crane and tension load cells can develop measurement or signal problems because of vibration, overload, environmental exposure, wiring faults, or installation issues. Identifying the symptom can help narrow down the likely cause.

Troubleshooting Approach

Start with a visual and mechanical inspection before testing the electrical system. Check the load cell, pins, shackles, mounting points, cables, connectors, and surrounding structure for damage or unwanted contact.

Next, check the zero reading and signal output against the manufacturer’s specifications. For wireless systems, also check battery condition, transmitter connections, and communication range.

If the problem continues, calibration or professional testing may be

Installing a Tension Load Cell Safely

A tension load cell must be installed in the correct load direction and securely integrated into the lifting system. For general installation guidance, see LCS-09: Load Cell Installation and Mounting Guide.

Before operation, check:

• Correct load direction: Apply force only in the direction specified by the manufacturer.
• Proper alignment: Keep the load cell aligned with the intended load path.
• Compatible shackles and pins: Confirm dimensions, ratings, and compatibility.
• Avoid side loading: Prevent bending, twisting, and lateral forces.
• Correct attachment points: Use approved connection points designed for the load.
• Cable protection: Protect cables from crushing, abrasion, sharp edges, moisture, and excessive bending.
• Environmental protection: Consider rain, dust, chemicals, corrosion, and temperature.
• Inspection before operation: Check the load cell, connections, cables, pins, shackles, and surrounding structure.

Avoid Side Loading

Tension load cells are designed to measure force in a specified direction. Side loading, bending, twisting, or misalignment can affect accuracy and may damage the sensor. The load should remain aligned with the intended tensile load path throughout operation.

Check the Complete Load Path

The load cell is only one component of the lifting system. Every component between the crane and the load must be suitable for the intended application.

Crane → Hook → Shackle/Link → Load Cell → Connection → Load

Check the capacity, condition, compatibility, alignment, and connection of each component. For safety-critical lifting applications, installation and inspection should follow the manufacturer’s instructions and applicable lifting requirements.

Tension Load Cell Maintenance Checklist

Regular inspection helps identify mechanical, electrical, and environmental problems before they affect load measurement or safe operation. A practical tension load cell maintenance checklist should include:

• Inspect the body: Look for cracks, deformation, impact damage, or other physical defects.
• Check shackles and pins: Confirm they are correctly fitted, secure, undamaged, and suitable for the application.
• Inspect cables: Check for cuts, crushing, abrasion, excessive bending, or moisture damage.
• Check connectors: Ensure connectors are clean, secure, and free from corrosion or moisture.
• Verify zero: Confirm the unloaded system returns to the expected zero reading.
• Check mounting and alignment: Make sure the load cell remains correctly aligned with the intended load path.
• Inspect for corrosion: Pay particular attention to exposed metal, connection points, pins, and areas exposed to moisture or chemicals.
• Confirm calibration status: Check that calibration or verification is current according to the application and required procedures.
• Check wireless equipment: For wireless load cells, verify the display, transmitter, battery condition, and communication system.
• Review inspection records: Record inspections, faults, repairs, calibration results, and unusual readings to identify developing problems.

FAQs About Tension Load Cells and Crane Scales

What load cell is used in a crane scale?

A crane scale can use tension load cells, load links, load pins, or shackle load cells, depending on the crane-scale design and how the load is transferred. Tension load cells measure pulling force directly, while load pins can replace structural pins and shackle load cells integrate force measurement into a lifting connection.

The correct choice depends on load capacity, mechanical arrangement, load direction, connection type, environment, and safety requirements.

What is a load pin?

A load pin is a force-sensing pin designed to measure the load transferred through a structural connection. It can replace a conventional pin in suitable equipment while measuring the force passing through that connection.

Load pins are commonly used in crane sheaves, pulleys, winches, clevises, lifting mechanisms, and structural pivot points.

How does a shackle load cell work?

A shackle load cell measures tensile force through a load-sensing body integrated into a shackle-style lifting connection. When a load is applied, the sensing element deforms slightly and internal strain gauges convert this deformation into an electrical signal.

The signal can be sent to a display, indicator, data logger, or wireless monitoring system. Correct shackle, pin, load rating, and connection compatibility are essential for safe operation.

Do crane load cells need certification?

Certification requirements depend on the application, jurisdiction, lifting equipment, site requirements, and applicable standards. A crane load cell used for general monitoring may have different requirements from equipment used for regulated or commercial weighing.

Calibration and certification are not interchangeable terms. Calibration verifies measurement performance against a reference, while certification or compliance documentation relates to specific requirements, standards, or regulatory conditions.

Final Takeaway

A tension load cell provides accurate force measurement for crane scales, lifting equipment and load monitoring applications. Choosing the right type requires careful consideration of rated capacity, load direction, mechanical connections, environmental conditions and the required output.

Load pins, shackle load cells and wireless load links can provide practical solutions for different lifting and weighing setups. However, safe operation also depends on correct installation, alignment, inspection, calibration and compliance with applicable equipment and safety requirements.