by Subhadeep Datta Subhadeep Datta


What Are Huck® Lockbolts?

A Lock Bolt is a two-piece fastener that consists of a hardened metal pin and a metal collar that swages into the grooves of the pin, forming a specific, measured clamp force to hold assembled parts.

The Huck® installation tool grips the pintail of a Lock Bolt and then pulls to close the gaps in the materials being joined. Inside the nose assembly, a hardened steel conical-shaped anvil is then forced down the collar to progressively squeeze, or swage, the collar material into the grooves. 

This direct metal-to-metal contact of the collar swaged into the grooves of the pin eliminates the loosening effects of transverse vibration.

  • Often installs in Under 2 Seconds
  • Consistent, High Clamp Force
  • Certified Maintenance-Free Joints
  • High Shear, Tensile, Pin Strength

Some of our best Huck® Lockbolts to provide strength to your machinery.

C6L ® The Original Vibration-Resistant Huck Bolt®

A result of Huck International innovation a half-century ago, the versatile C6L® Huck Bolt® remains the number one fastening system for applications that require a strong, vibration-resistant seal today.

C6L’s exclusive locking groove design ensures a permanent fit that resists loosening. That means it’s ideal for applications from general manufacturing to such high-vibration applications as HVAC, trailer and container assembly, rotary and rotating equipment, shopping carts, railroad, and transit cars, geodesic structures, and many others.

In addition to offering superior fastening performance, the C6L system reduces labor and installation costs, along with rework and warranty expenses. Using the C6L eliminates the need to hire certified welders or specially trained employees because workers can be instructed to install these foolproof fasteners in a matter of minutes. The C6L is simply stronger, easier to install, and more durable than welding, adhesives, or conventional threaded fastening systems. The C6L is available in Grade 2, Grade 5, and Grade 8.

Available Sizes: 3/16”, 1/4”, 5/16”, 3/8”

Materials: Steel, Aluminum, Stainless Steel

Head styles: Round, Truss, Flush, 98T

The C6L’s unique design virtually eliminates installation errors caused by operator or tool variables. The C6L ensures that once the collar swage is complete, the pintail breaks off and the fastener is tightly installed. No rework is required. You can count on consistent, highly-uniform clamp force with every C6L installation, time after time.

1 Wide bearing collar and head spread the load to ensure structural integrity.

2 Initial long length of fastener enables pull-out of large gaps.

3 Excellent gap pull-out and high retained clamp.

4 High-fatigue, annular lock groove form extends the life of your structure.

Huck® C50L® The Fastener That Has Defined Huck Bolts for More Than 50 years

The C50L® offers superior vibration resistance and overall durability for heavy-duty fastening jobs and is ideal for use within applications where consistent, uniform high clamp force is required. Testing has proven that C50L fasteners meet, or exceed the performance of torqued bolts in both shear and tensile strength, as well as fatigue life. For heavy-duty applications ranging from railcar to mining equipment manufacturing, the C50L delivers superior vibration resistance and overall durability.

Available Sizes: 1/2”, 5/8”, 3/4”, 7/8”, 1”, 1-1/8”, 1-3/8”

Materials: Steel, Aluminum

Head styles: Round, Truss, Large Truss, 90° Flush, Thread Head

Unlike threaded fasteners, the C50L HuckBolt® delivers consistent installation results. High costs of calibrating, maintaining, and replacing tools are eliminated. Also, installation does not require expensive, highly experienced workers.

1 Swaged-on collar forms a permanent, vibration-proof connection.

2 Initial long length of fastener enables pull-out of large gaps.

3 Consistent, repeatable pre-load

How Do Huck® Bolts Work?

Clamp Force or Pre-Load

In the initial stages of the installation process, the Huck® lock bolt tool engages and pulls on the pintail. The joint is pulled together before the conical-shaped cavity of the nose assembly is forced down the collar. This progressively locks (swages) it into the grooves of the harder pin. The pin and swaged collar combine to form the installed fastener. The squeezing action reduces the diameter of the collar, increasing its length. This in turn stretches the pin, generating a clamp force over the joint.

Shear strength

Varies according to the material strength and minimal diameter of the fastener. By increasing the diameter or the grade of material, the shear strength of the fastener can be increased.

Tensile strength

The tensile strength of Lock Bolts is dependent on the shear resistance of the collar material and the number of grooves it fills.

Lock Bolt Installation

Installing Huck® Bolts Using Huck Bolt Installation Tools.

  1. Before installation, you need to make sure that you have the right size of Huck® bolts for the process. You would want to go for one that has the right size and strength for your needs.

  1. Put the Huck® bolt in the hole prepared for it. Try to make sure that the bolt is the right fit for the application, or there are chances of lateral movement. This movement can weaken the joint over time.

  1. When you place the Huck® bolt in the cavity, the collar will be over the pinhead. When you use a Huck® lockbolt installation tool for the process, the reliable collar will form a durable connection that lasts for years.

  1. We have many different kinds of hydraulic machines that can help with your installation process. We have hydraulic and pneudraulic powered Huck® bolting machines that effectively help you install Huck® bolts in seconds. A few of our best products are the Swage forward Range and Huck® Range Force Battery Installation Tool.

  1. From the wide range of tools available, try to choose the perfect match for your needs. Put the machine’s nosepiece into the collar, over the pintail. Activate the Huck® bolt tooling.

  1. The activation process will put pressure on the collar and brings the pieces of the bolt together. It ensures a sturdy design that cannot become loose over time.

  1. Once the process is complete, the tool breaks from the pintail, and you can remove the machine.