Types of Cable Carriers
A cable carrier, also known as a cable chain, cable tray, or energy chain, is a mechanical system designed to protect, guide, and support moving cables and hoses in industrial, automation, and machinery environments. Without proper cable management, wires are vulnerable to abrasion, twisting, crushing, and premature failure due to constant motion or environmental exposure. Cable carriers ensure safety, longevity, and organization of electrical and fluid lines, while also enhancing the visual clarity and serviceability of complex systems.
These carriers are essential in applications involving repetitive motion, such as robotics, CNC machines, automated assembly lines, and gantry systems. Below is a detailed breakdown of the most common types of cable carriers, their features, advantages, and ideal use cases.
Drag Chain
Also known as a cable drag chain or cable carrier chain, this type is engineered for dynamic applications where cables move back and forth continuously.
Advantages
- Excellent protection against mechanical stress
- Supports high cycle rates and repetitive motion
- Modular design for easy installation and maintenance
- Available in plastic and metal variants
Limitations
- Requires proper bending radius planning
- Can be noisy in high-speed operations
- Needs precise alignment for optimal performance
Best for: CNC machines, robotics, linear actuators, automated conveyors
Plastic Cable Carrier
Made from high-performance polymers like nylon or polypropylene, these lightweight carriers offer excellent corrosion resistance and smooth operation.
Advantages
- Resistant to chemicals, moisture, and UV exposure
- Lightweight and easy to install
- Low noise and low friction operation
- Ideal for cleanroom and food processing environments
Limitations
- Less suitable for very high loads or extreme temperatures
- Lower mechanical strength than metal alternatives
- May degrade under prolonged UV exposure (depending on material)
Best for: Packaging machines, medical equipment, chemical plants, indoor automation
Double-Sided Cable Carrier
Designed with channels on both sides, this carrier allows simultaneous routing of cables in opposite directions, improving symmetry and balance in complex setups.
Advantages
- Efficient use of space in bidirectional systems
- Even weight distribution reduces stress on mounting points
- Reduces clutter and improves cable organization
- Supports synchronized motion in dual-axis machinery
Limitations
- Larger footprint compared to single-sided carriers
- More complex installation and alignment required
- Higher cost due to increased material and design complexity
Best for: Dual-axis robots, overhead gantries, symmetrical automation systems
Energy Chains
A specialized form of cable carrier designed specifically for continuous, high-speed motion, often used in automated production environments.
Advantages
- Optimized for long travel distances and high speeds
- Integrated cable management with separators and dividers
- Available in modular kits for customization
- Engineered for millions of cycles with minimal wear
Limitations
- Premium pricing for high-end models
- Requires precise load and bend radius calculations
- May need regular inspection in harsh environments
Best for: Automotive assembly lines, high-speed pick-and-place robots, automated warehouses
Spring-Loaded Cable Carrier
Equipped with internal springs or tensioning mechanisms, this type automatically adjusts to cable length and movement, maintaining constant tension.
Advantages
- Self-retracting design saves space
- Prevents cable sagging and tangling
- Ideal for vertical or telescopic movements
- Reduces manual adjustments and maintenance
Limitations
- Spring fatigue over time in continuous use
- Limited extension range compared to rigid carriers
- Not suitable for heavy-duty or high-load applications
Best for: Elevators, lift tables, medical imaging devices, retractable systems
Steel Mesh Cable Carrier
Constructed from interwoven steel wires, this robust carrier offers maximum strength and heat dissipation for demanding industrial environments.
Advantages
- Extremely durable and resistant to impact and crushing
- Excellent ventilation and heat dissipation
- Fire-resistant and suitable for high-temperature areas
- Can support heavy bundles of cables and hoses
Limitations
- Heavier and more difficult to install
- Potential for sharp edges requiring protective covers
- Prone to rust if not galvanized or stainless
Best for: Steel mills, foundries, heavy machinery, outdoor cranes, high-heat environments
| Type | Material | Durability | Flexibility | Best Application |
|---|---|---|---|---|
| Drag Chain | Plastic/Metal | High | High | Automated machinery, linear motion systems |
| Plastic Cable Carrier | Engineered Polymer | Medium-High | High | Light-duty automation, corrosive environments |
| Double-Sided Carrier | Plastic/Metal | High | Medium | Bidirectional systems, gantry robots |
| Energy Chains | Reinforced Plastic | Very High | Very High | High-speed automation, robotics |
| Spring-Loaded | Plastic/Metal + Spring | Medium | High (Retractable) | Vertical lifts, retractable systems |
| Steel Mesh | Stainless/Galvanized Steel | Exceptional | Low-Medium | Heavy industry, high-heat environments |
Expert Tip: Always calculate the required bend radius, travel length, and total weight of cables before selecting a cable carrier. Using carriers that are too small or too rigid can lead to premature cable failure and system downtime.
In summary, choosing the right cable carrier depends on the specific demands of your application, including movement type, environmental conditions, load requirements, and space constraints. Whether you need the lightweight flexibility of plastic carriers or the rugged strength of steel mesh, proper selection ensures reliable, long-term performance and reduces maintenance costs.
Function and Design of Cable Carrier Systems
Cable carriers—also known as drag chains or cable management systems—are essential components in modern industrial and automation environments. Their primary function is to protect, guide, and organize moving cables and hydraulic lines, preventing damage caused by friction, twisting, and environmental exposure. Without proper cable support, exposed wiring is vulnerable to wear, tangling, and premature failure, leading to costly downtime and maintenance. A well-designed cable carrier ensures smooth, reliable operation in dynamic applications such as CNC machines, robotics, automated assembly lines, and material handling systems.
Key Design Considerations for Cable Carriers
The effectiveness of a cable carrier depends on several critical design factors that must be tailored to the specific application. These include material composition, mechanical flexibility, load handling, ease of maintenance, and customization capabilities. Below is a detailed breakdown of each element:
Material Selection
The choice of material significantly impacts the durability, weight, and environmental compatibility of a cable carrier. Common materials include:
- Steel: Offers high strength and rigidity, ideal for heavy-duty industrial environments with mechanical stress and high temperatures.
- Aluminum: Lightweight and corrosion-resistant, suitable for applications requiring reduced moving mass and moderate durability.
- High-Performance Polymers (e.g., Nylon, PEEK): Resistant to chemicals, moisture, and abrasion, making them perfect for corrosive or wet environments such as food processing, pharmaceuticals, and marine applications.
Material selection should align with operational conditions, including temperature extremes, exposure to oils or solvents, and required service life.
Tension and Flexibility
One of the core functions of a drag chain is to maintain consistent tension on cables while allowing continuous flexing during machine movement. The articulated link design enables smooth bending along a defined radius, minimizing stress on internal cables. Proper bend radius calculation is crucial—too tight a curve can cause internal abrasion or kinking, while too loose may lead to slack and entanglement.
Advanced cable carriers feature low-friction interior surfaces and separators to prevent cables from rubbing against each other, extending their operational lifespan in high-cycle applications.
Load Capacity
Load capacity refers to the total weight and volume of cables and hoses a carrier can safely support without deformation or fatigue. Engineers must account for:
- The number, diameter, and weight of cables/hoses
- Dynamics of motion (e.g., acceleration, travel length, cycle frequency)
- Use of separators or shelves to evenly distribute internal loads
Overloading a cable carrier can result in structural failure, accelerated wear, or restricted movement. It's recommended to fill the carrier to only 70–80% of its internal capacity to allow for free movement and heat dissipation.
Installation and Maintenance
User-friendly design is vital for reducing setup time and ensuring long-term reliability. Modern cable carriers often feature:
- Modular link systems that allow quick assembly and disassembly
- Side-opening or snap-open designs for easy cable insertion and replacement
- Tool-free mounting brackets and alignment guides
For maintenance, accessible designs enable rapid inspection, cleaning, and component replacement without dismantling the entire system—minimizing machine downtime and labor costs.
Customization and Application-Specific Design
Many industrial and robotic applications require non-standard configurations. Custom cable carriers can be engineered to meet precise requirements, including:
- Specific lengths and bend radii
- Unique cross-sectional shapes (e.g., flat, rectangular, or enclosed)
- Integrated features like shielding, grounding, or fluid channels
- Color-coding or labeling for easy identification in complex systems
Custom solutions are especially valuable in robotics, medical equipment, and aerospace systems where space constraints and precision are critical.
Environmental and Operational Factors
Beyond basic design, real-world performance depends on environmental conditions. Key considerations include:
- Temperature Range: Materials must withstand both high heat (e.g., near engines) and extreme cold without becoming brittle.
- Dust and Debris: Sealed or fully enclosed carriers prevent contamination in dirty environments.
- Noise Reduction: Polymer-based carriers are quieter than metal ones, beneficial in noise-sensitive areas.
- Fire Resistance: Flame-retardant materials are essential in electrical enclosures and public infrastructure.
| Design Factor | Impact on Performance | Best Practices |
|---|---|---|
| Material Type | Determines durability, weight, and chemical/thermal resistance | Select polymers for corrosive environments; metals for high-load, high-temperature settings |
| Bend Radius | Affects cable lifespan and flexibility | Follow manufacturer specs; typically 7.5x–10x cable outer diameter |
| Fill Capacity | Impacts airflow, heat dissipation, and cable movement | Limit to 70–80% of internal volume; use separators when needed |
| Motion Type | Influences stress distribution and wear patterns | Use closed-loop systems for vertical motion; add support rollers for long spans |
Conclusion and Best Practices
Important: Improper selection or installation of a cable carrier can lead to cable failure, machine downtime, and safety hazards. Always consult engineering specifications and application experts when designing or replacing a cable management system. Investing in a high-quality, properly designed carrier pays off through increased reliability, reduced maintenance, and extended equipment life.
Scenarios for Cable Carrier Applications
Selecting the right cable carrier and tray system is essential for ensuring reliable power, signal, and data transmission in dynamic and demanding environments. The length, material, and design of a cable carrier must be carefully matched to the application’s mechanical, environmental, and operational requirements. Below is a detailed overview of common use cases across industries, including material recommendations, performance needs, and installation considerations.
Industrial Machinery
Heavy-duty industrial equipment such as CNC machines, presses, and conveyors subjects cables to constant movement, mechanical stress, and high temperatures. Steel or steel-mesh cable carriers are ideal for these environments due to their exceptional durability and resistance to impact, abrasion, and thermal exposure.
- Withstands heavy loads and repetitive motion cycles
- Resists deformation under high compression and shear forces
- Protects against sparks, welding debris, and coolant splashes
- Often includes internal separators to prevent cable tangling
Best practice: Use carriers with smooth inner surfaces to reduce friction and extend cable life
Robotics
In robotic arms and automated guided systems (AGVs), precise and continuous motion demands highly flexible yet tension-controlled cable management. Drag chains (also known as energy chains) are specifically engineered for dynamic applications, providing controlled bending radius and consistent support throughout the movement cycle.
- Enables full-range articulation without cable strain
- Minimizes wear from frequent directional changes
- Available in modular plastic or lightweight metal versions
- Supports high-speed data lines and servo cables
Key tip: Match the bend radius of the carrier to the minimum bend specification of the cables used
Construction and Heavy Equipment
Excavators, cranes, and mobile construction machinery operate in rugged outdoor conditions with extreme vibrations and shifting loads. Steel cable carriers are preferred due to their high tensile strength and ability to support long cable runs under tension.
- Resists deformation from heavy cable bundles
- Survives exposure to dirt, gravel, and weather extremes
- Secures hydraulic, power, and control lines in articulated booms
- Often features protective covers to prevent debris ingress
Design note: Consider telescoping or nested carriers for compact retraction in limited spaces
Automated Manufacturing Systems
In high-speed assembly lines and pick-and-place systems, cables undergo rapid, repetitive motion. Cable carriers—particularly energy chains—are critical for organizing, guiding, and protecting cables from fatigue and entanglement.
- Supports thousands of cycles per day with minimal maintenance
- Reduces downtime by preventing cable snags and failures
- Compatible with sensor, pneumatic, and Ethernet cables
- Available in low-noise variants for quieter operation
Efficiency tip: Pre-assembled carrier kits speed up installation and reduce errors
Aerospace and Aviation
Weight savings and electromagnetic compatibility are critical in aircraft and aerospace systems. Plastic cable carriers—typically made from high-performance polymers like PEEK or nylon—are widely used due to their lightweight nature and non-conductive properties.
- Minimizes added weight in flight-critical systems
- Does not interfere with avionics or communication signals
- Resistant to fuels, hydraulic fluids, and temperature extremes
- Meets strict flammability and outgassing standards (e.g., FAA, MIL-STD)
Compliance note: Ensure materials meet aerospace-grade certifications for safety and reliability
Commercial Buildings
In HVAC, plumbing, and electrical infrastructure, wire baskets and ladder-type cable trays provide accessible and scalable cable management. These open-design systems allow for easy inspection, modification, and maintenance of power and control wiring.
- Simple to install and expand as building needs evolve
- Facilitates airflow and reduces heat buildup in cable bundles
- Supports large-diameter power cables and conduit runs
- Galvanized steel or aluminum options resist indoor corrosion
Installation advantage: Compatible with standard mounting brackets and seismic supports
Marine and Offshore
Offshore platforms, ships, and subsea equipment face constant exposure to saltwater, humidity, and corrosive elements. Stainless steel or specially coated steel cable carriers are essential to maintain integrity and prevent premature failure.
- Resists saltwater corrosion and UV degradation
- Withstands vibration from engines and wave motion
- Protects critical navigation, communication, and propulsion cables
- Often includes drainage features to prevent water accumulation
Durability tip: Opt for marine-grade 316 stainless steel for maximum longevity
Professional Recommendation: When selecting a cable carrier, always evaluate the total dynamic environment—not just the load and movement, but also temperature, chemical exposure, and accessibility for maintenance. For hybrid applications (e.g., industrial robots on marine vessels), consider composite carriers that combine corrosion-resistant materials with high flex life. Additionally, use software tools or manufacturer calculators to determine the correct carrier length, bend radius, and support span for optimal performance.
| Application | Recommended Carrier Type | Material | Key Benefits |
|---|---|---|---|
| Industrial Machinery | Steel Mesh or Heavy-Duty Drag Chain | Carbon Steel, Stainless Steel | Durability, heat resistance, high load capacity |
| Robotics | Energy Chain (Plastic or Hybrid) | Nylon, PEEK, Aluminum | Flexibility, precision motion, low friction |
| Construction & Heavy Equipment | Telescoping Steel Carrier | Galvanized Steel | High tensile strength, rugged durability |
| Automated Manufacturing | Modular Energy Chain | Reinforced Plastic | High cycle life, low maintenance, noise reduction |
| Aerospace & Aviation | Lightweight Drag Chain | High-Performance Polymers | Weight savings, EMI immunity, chemical resistance |
| Commercial Buildings | Ladder Tray or Wire Basket | Galvanized Steel, Aluminum | Easy access, scalable, cost-effective |
| Marine & Offshore | Corrosion-Resistant Drag Chain | Stainless Steel 316 | Longevity in saltwater, vibration resistance |
Additional Selection Criteria
- Bend Radius: Must match or exceed the minimum bend radius of the enclosed cables to prevent damage
- Travel Length: Total unsupported span affects carrier stability; longer runs may require intermediate supports
- Speed and Acceleration: High-speed applications need low-inertia carriers with smooth gliding mechanisms
- Environmental Sealing: Optional covers or flaps protect against dust, water, and contaminants
- Modularity: Segment-based designs allow for easy replacement and customization
Choosing the Right Cable Carrier: A Comprehensive Guide
Selecting the appropriate cable carrier is essential for ensuring the longevity, safety, and efficiency of your cable management system. Whether used in industrial automation, robotics, or manufacturing environments, a well-chosen cable carrier protects cables from mechanical stress, environmental hazards, and operational wear. This guide outlines the critical factors to consider when selecting a cable carrier to match your specific application needs.
Important Note: Improper cable carrier selection can lead to premature cable failure, unplanned downtime, and increased maintenance costs. Always evaluate your application’s full operational profile before making a decision.
Key Factors in Cable Carrier Selection
- Load Capacity: The carrier must support the total weight and volume of all cables and hoses it will carry. Consider both the number and diameter of cables to avoid overcrowding. Overloading can cause sagging, internal friction, and damage to insulation or conductors. Ensure the carrier provides adequate internal space (typically 20–30% fill capacity) for free movement and heat dissipation.
- Environmental Conditions: Assess the operating environment thoroughly. For corrosive settings (e.g., chemical plants or washdown areas), use corrosion-resistant materials like reinforced plastics (nylon, polyacetal) or stainless steel. In high-temperature environments (e.g., near furnaces or welding stations), steel carriers with heat-resistant coatings are ideal. For cold or cryogenic conditions, ensure the material remains flexible and impact-resistant at low temperatures.
- Motion Requirements: Determine whether your application involves dynamic motion. For continuous or repetitive movement (e.g., CNC machines, robotic arms), use drag chains or energy chains specifically engineered for flexibility and durability under cyclic stress. For static installations (e.g., fixed control panels or overhead trays), ladder-type cable carriers or trunking systems are sufficient and more cost-effective.
- Installation Space and Layout: Measure the available space for routing and bending radius. In confined areas, opt for compact, low-profile carriers with a small bend radius. For longer travel paths or complex 3D movements, consider modular designs that allow smooth articulation. Proper space planning prevents cable pinching and ensures full range of motion without interference.
- Cable Organization and Protection: A well-designed cable carrier not only organizes wires but also extends their service life by minimizing exposure to dust, moisture, vibration, and mechanical tension. Disorganized cabling across factory floors poses tripping hazards, increases wear, and complicates troubleshooting. Carriers keep cables neatly enclosed, improving safety, accessibility, and system reliability.
- Customization Needs: Some applications require specialized shapes, mounting options, or integrated features (e.g., separators, shielding, or quick-release mechanisms). While customizable carriers offer precise fit and function, they often involve longer lead times and higher costs. Evaluate whether standard models can be adapted before opting for full customization.
- Budget and Lifecycle Value: While initial cost is a consideration, focus on total cost of ownership. High-quality carriers may have a higher upfront price but offer longer service life, reduced maintenance, and fewer system failures. Compare material durability, expected lifespan, and replacement frequency to determine long-term value.
| Selection Factor | Recommended Solutions | Material Options | Common Applications |
|---|---|---|---|
| High Load & Dynamic Motion | Reinforced energy chains with separators | Steel, reinforced nylon | Industrial robots, CNC machines |
| Corrosive Environments | Sealed plastic drag chains | Polypropylene, POM (Delrin) | Food processing, chemical plants |
| High Temperature | Heat-resistant steel carriers | Stainless steel, coated carbon steel | Metalworking, foundries |
| Space-Constrained Installations | Low-bend-radius mini carriers | Flexible polymers, hybrid materials | Medical devices, compact automation |
| Static or Low-Movement Use | Ladder-style or trough carriers | PVC, aluminum, steel | Control cabinets, conveyor systems |
Expert Tip: Always perform a dry run of the cable carrier’s full motion cycle before final installation. This helps identify potential binding, twisting, or clearance issues and ensures cables move freely within the carrier without excessive tension or slack.
Additional Selection Tips
- Use cable separators or dividers to prevent abrasion between power, signal, and data cables.
- Ensure the carrier’s bend radius matches or exceeds the minimum bend radius of the most sensitive cable in the bundle.
- Consider carriers with transparent or open-side designs for easier visual inspection and maintenance.
- Verify compatibility with existing mounting systems and alignment requirements.
- Consult manufacturer catalogs or use online configurator tools for precise sizing and compatibility checks.
Choosing the right cable carrier is more than just a mechanical decision—it's an investment in system reliability and operational efficiency. By carefully evaluating load, environment, motion, space, and lifecycle costs, you can select a solution that enhances performance, reduces downtime, and protects your critical cabling infrastructure. When in doubt, consult with a cable management specialist to ensure optimal selection for your unique application.
Frequently Asked Questions About Cable Carriers and Cable Trays
Q1: How does one determine the right size of a cable carrier?Selecting the correct size of a cable carrier is crucial for ensuring optimal performance, longevity, and safety of your cable management system. The size should be based on several key factors:
- Cable Bundle Diameter: Measure the total diameter of all cables and hoses when grouped together. The internal height and width of the cable carrier should comfortably accommodate this bundle.
- Bend Radius Clearance: Ensure the carrier’s bend radius matches or exceeds the minimum bend radius of the most sensitive cable in the bundle to prevent damage during movement.
- Future Expansion: Always allow 20–30% additional space within the carrier to account for future additions or replacements without needing to upgrade the entire system.
- Dynamic Movement Requirements: In applications involving continuous motion (e.g., robotics, CNC machines), ensure there’s enough room for cables to move freely without friction or compression.
Proper sizing not only protects your cables but also reduces wear, improves system efficiency, and minimizes downtime due to failures.
Q2: Can cable trays be utilized outdoors?Yes, cable trays can be effectively used in outdoor environments, provided they are constructed from durable, weather-resistant materials. Here’s what makes them suitable:
- Galvanized Steel: Offers excellent corrosion resistance due to a protective zinc coating, making it ideal for humid, wet, or industrial outdoor settings.
- Stainless Steel: Provides superior resistance to rust, salt spray, and extreme temperatures—perfect for coastal areas or harsh climates.
- Aluminum: Lightweight and naturally corrosion-resistant, often used where weight is a concern and moderate weather protection is needed.
- Coated or Polymer-Based Trays: Non-metallic options like fiberglass-reinforced plastic (FRP) are immune to rust and ideal for chemically aggressive environments.
When installing cable trays outdoors, ensure proper grounding, use UV-resistant cables, and consider covers to protect against rain, debris, and direct sunlight exposure.
Q3: What is the difference between a cable carrier and a cable tray?While both cable carriers and cable trays manage and organize cables, they serve different purposes and are designed for distinct applications:
| Feature | Cable Carrier | Cable Tray |
|---|---|---|
| Primary Use | Used in dynamic applications where cables move repeatedly (e.g., robotics, automation equipment). | Designed for static installations to support and route large volumes of cables in buildings, plants, or outdoor runs. |
| Movement Capability | Engineered for continuous flexing and reciprocating motion (drag chains). | Fixed in place; not intended for movement. |
| Protection Level | High—fully encloses cables to protect against abrasion, dust, and mechanical stress. | Moderate—supports cables openly, offering less physical protection but better airflow and accessibility. |
| Materials | Plastic (e.g., nylon), steel, or hybrid designs for flexibility and durability. | Steel (galvanized/stainless), aluminum, or non-metallic composites. |
| Installation Environment | Machinery, industrial automation, moving arms, and automated assembly lines. | Power distribution systems, data centers, HVAC systems, and utility infrastructure. |
In short, cable carriers are dynamic protective conduits for moving cables, while cable trays are static support structures for stationary cable routing.
Q4: What are the considerations for maintenance of cable trays?Regular maintenance of cable trays ensures long-term reliability, safety, and compliance with electrical codes. Key maintenance practices include:
- Visual Inspections: Check for signs of corrosion, deformation, loose fasteners, or structural damage—especially in outdoor or high-moisture environments.
- Cable Organization: Ensure cables are properly secured and not overloaded. Avoid overfilling trays beyond recommended capacity (typically 40–50% fill for power cables).
- Cleanliness: Remove dust, dirt, and debris that can trap moisture or create fire hazards. In industrial settings, particulate buildup can accelerate wear.
- Ventilation and Heat Dissipation: Confirm that cables have adequate airflow to prevent overheating, particularly in enclosed spaces or high-density installations.
- Grounding and Bonding: Verify that metal trays remain properly grounded to prevent electrical hazards and electromagnetic interference (EMI).
- Environmental Exposure: Monitor for UV degradation (in plastics), salt corrosion (near coasts), or chemical exposure that may weaken tray materials over time.
Scheduled inspections—quarterly or semi-annually depending on the environment—help identify issues early and extend the lifespan of both the tray and the cables it supports.
Q5: Can different types of cables be installed in a single cable carrier?Yes, multiple types of cables can be installed in a single cable carrier, but with important caveats to maintain performance and safety:
- Segregation by Type: Group similar cables together—such as power, control, signal, or data cables—and avoid mixing high-voltage lines with sensitive signal wires to prevent electromagnetic interference (EMI).
- Use of Separators: Many cable carriers come with built-in dividers or optional internal separators to isolate different cable types and reduce crosstalk.
- Avoid Tangling and Stress: In dynamic applications (like drag chains), cables must move freely without snagging. Mixing stiff and flexible cables can cause uneven wear or binding.
- Hose Compatibility: Hydraulic or pneumatic hoses can be routed alongside cables if properly secured and compatible with the carrier’s movement profile.
- Cable Compatibility: Ensure all cables have similar bend radii, weight, and flexibility characteristics to prevent premature fatigue of any single component.
While combining cables in one carrier is efficient, improper installation can lead to signal noise, reduced cable life, or even system failure. Always follow manufacturer guidelines and industry best practices for cable segregation and fill capacity.










