Fasteners are fundamental to mechanical engineering and structural design. While bolts and screws are the most recognized types, there’s an entire category of fasteners that provide unique mechanical advantages in both motion and alignment applications. One such fastener is the clevis fastener, a component celebrated for its versatility, adjustability, and simplicity. This guide provides a comprehensive overview of clevis fasteners—from types and uses to materials, manufacturing processes, and maintenance practices.
What Is a Clevis Fastener?
A clevis fastener is a mechanical component used to create a secure, pivoting connection between two parts. It consists of three core elements:
Clevis: A U-shaped or forked connector with holes on each end.
Clevis Pin: A cylindrical pin that passes through the holes to hold the clevis in place.
Retaining Mechanism: A cotter pin, retaining clip, or other device that prevents the pin from falling out.
This configuration allows for easy disassembly, making clevis fasteners ideal for applications requiring frequent removal, maintenance, or motion.
Applications of Clevis Fasteners
Clevis fasteners are used in a wide variety of industries due to their ability to allow movement while maintaining structural integrity:
Mechanical Linkages: Steering mechanisms, throttle linkages, and suspension arms.
Construction Equipment: Connecting hydraulic arms and pivot points in cranes and excavators.
Hydraulic and Pneumatic Systems: Securing actuators and pistons in a movable yet fixed alignment.
Agriculture: Tractors, plows, and harvesting machinery use clevis hitches to attach interchangeable tools.
Industrial Machinery: Conveyor belts, control levers, and support rods.
Architecture and Building: Beam support, tie rod assemblies, and structural bracing systems.
History and Evolution of Clevis Fasteners
The concept of clevis-style connectors dates back to ancient times when wooden joints were pinned together using metal rods. In the Middle Ages, blacksmiths developed early forms of clevis pins for use in carts and armor. The Industrial Revolution standardized mechanical linkages, leading to the mass production of clevis fasteners for steam engines and early manufacturing tools. Today, CNC machining and advanced metallurgy have further refined clevis design, improving strength, tolerance, and material selection.
Types of Clevis Fasteners
Standard Clevis Pin
A basic cylindrical pin with a hole for a cotter pin. Commonly used in light to moderate load applications.
Shouldered Clevis Pin
Features a fixed shoulder for precise depth and lateral positioning. Reduces play and improves alignment.
Cotterless Clevis Pin
Built with an integrated retention feature, eliminating the need for separate cotter pins. Speeds up assembly.
Clevis Bolt
A threaded clevis pin that screws into tapped holes or nuts. Provides greater resistance to vibration and loosening.
Clevis Yoke
A forked end (yoke) connected by a bar or rod, often used in tie rod systems or actuation linkages.
Tapped Clevis
Clevis ends with internal threads for connection to threaded rods. Offers customizable attachment options.
Eye and Clevis Pins
Combination fasteners with an eye at one end and clevis at the other, facilitating loop-to-pivot attachments.
Specialized Clevis Fasteners
Designed for extreme environments (marine, aerospace, military), often made from special alloys or with custom coatings for corrosion resistance, high temperature, or magnetic neutrality.
Threaded vs Unthreaded Clevis Pins
Threaded Clevis Pins
Adjustability: Fine-tuning of connection length.
High Load Capacity: Threads distribute force more evenly.
Reduced Lateral Movement: Secure fit prevents unwanted rotation.
Unthreaded Clevis Pins
Simplicity: Slide-in design allows quick installation.
Cost-Effective: Fewer machining steps, lower material costs.
Quick Assembly/Disassembly: Ideal for frequently serviced machinery.
Choosing Between the Two: Use threaded pins for permanent, load-bearing setups. Choose unthreaded pins for low-stress or frequently adjusted connections.
Materials Used for Clevis Fasteners
The right material depends on the application’s load, environment, and cost constraints:
| Material | Properties & Applications |
| Carbon Steel | Strong, affordable, suitable for general industrial use. |
| Alloy Steel | High strength, wear-resistant, used in heavy machinery. |
| Stainless Steel | Corrosion-resistant, ideal for marine, food, and medical. |
| Aluminum | Lightweight, corrosion-resistant, used in aerospace. |
| Brass | Aesthetic, low-load, corrosion-resistant, decorative use. |
| Bronze | Strong and corrosion-resistant, good for marine applications. |
| Titanium | Excellent strength-to-weight ratio, aerospace and defense. |
| Plastics | Lightweight, non-load applications, chemically resistant. |
| Special Alloys | Monel, Inconel, Hastelloy for extreme conditions. |
Clevis Fastener Manufacturing Process
Step 1: Material Selection
Based on application-specific needs for strength, corrosion resistance, and machinability.
Step 2: Material Preparation
Cutting, straightening, or shaping the material to the required blank size.
Step 3: Forming and Shaping
Forging: Increases strength via grain alignment.
Cold-heading: Efficient for high-volume pin production.
Machining: For tight-tolerance or complex features.
Step 4: Machining and Threading
CNC turning, milling, and threading (if needed) are used to create pin holes, grooves, and precision shapes.
Step 5: Heat Treatment
Processes such as quenching, tempering, or case hardening are applied to improve hardness and tensile strength.
Step 6: Finishing and Surface Treatment
Zinc, chrome, phosphate, or anodizing coatings enhance performance and durability.
Deburring and polishing may be applied for smooth operation.
Step 7: Quality Control
Dimensional checks, tensile testing, and corrosion resistance verification ensure reliability.
Step 8: Assembly and Packaging
Parts are assembled (if needed), cleaned, labeled, and packaged according to client requirements.
Installation Best Practices
Choose the Correct Size & Type: Ensure compatibility in diameter, length, and load rating.
Inspect for Damage: Check for burrs, corrosion, cracks, or deformation.
Use Lubrication: Prevent seizing and ease installation.
Ensure Alignment: Misaligned holes can damage the fastener or reduce function.
Apply Correct Torque: For threaded pins, avoid under- or over-tightening.
Secure the Retaining Mechanism: Cotter pins or clips must be fully seated.
Follow Manufacturer Guidelines: Always refer to the product’s technical data.
Inspection and Maintenance
Regular Inspection
Visual Check: Rust, fatigue, wear, and alignment.
Check Movement: There should be no excessive play.
Retaining Mechanism: Secure and undamaged.
Maintenance Tips
Lubrication: Periodic application of grease or oil.
Component Replacement: Swap out worn or rusted pins.
Retightening: For threaded pins, confirm torque levels.
Clean Surroundings: Prevent contaminants from interfering with fastener function.
Scheduled Maintenance: Especially important in high-load or safety-critical applications.
Professional Evaluation: In aerospace or structural use, certified inspections may be required.
Conclusion
Clevis fasteners serve as critical components across mechanical, industrial, automotive, and aerospace fields. Their simple yet adaptable design allows for both static and dynamic connections that are easy to install, inspect, and maintain.
Whether you’re selecting clevis pins for agricultural equipment or aerospace linkages, the right choice of material, pin type, and installation method will ensure long-term performance and reliability.
FAQ
How much is a clevis fastener?
Prices can range from $0.20 for simple steel pins to over $10 for custom alloy or aerospace-grade fasteners. Quantity and material significantly affect cost.
Which clevis fastener is best?
It depends on your application. Threaded types offer security and load-bearing capabilities, while unthreaded options are ideal for easy removal and low-load applications.
🌐 Internal Links:
Heat Treatment in Metal Manufacturing
Choosing the Right Fastener Material
