Products

Connecting Link/ Hammerlok A7

Both Hammerlok A6 and A7 are coupling links used to connect lifting chains, hooks, and other rigging components.

Hammerlok A6: Often referred to simply as a connecting link or hammerlock, it is typically forged from super alloy steel, quenched, and tempered for high strength.

Hammerlok A7: Specifically described as a connecting link featuring a “Spring and Pin Shaft”.

Both types are designed for use with Grade 80 chains and undergo similar safety testing and the primary difference lies in the specific model designation, with A7 often highlighting the pin/spring mechanism.

Specifications

Product Characteristics:

  • Functional Utility: Specifically engineered to bridge connections where chain link dimensions are restrictive. Acting as a robust intermediary, the link facilitates secure attachment to hooks, shackles, or master links when the chain’s internal clearance is insufficient.

  • Metallurgy: Forged from super alloy steel; Quenched and Tempered for high-tenacity performance.

Here are the key safety and precautions when using hammerloks:

  1. Inspection Before Each Use

Check for Damage: Inspect for any signs of deformation, cracks, or corrosion.

Pin Integrity: Ensure the load pins are secure, properly seated, and not bent.

Wear Limits: Replace the unit if there is a 10% or more reduction in the original dimension at any point due to wear.

Discard Damaged Units: Never use a hammerlok that has been involved in an accident or shows signs of misuse.

  1. Proper Installation and Use

Correct Orientation: Loop one half of the hammerlok through the towing vehicle’s attachment point (e.g., welded V-ring) and the other half through the end of the safety chain.

Drive the Pin: Secure the two halves by driving the load pin through, ensuring it is fully inserted.

Lubrication: Lubricate swivel joints to maintain smooth rotation.

Avoid Excessive Force: Do not use a hammerlok to “shorten” a chain by twisting it; instead, use it to permanently attach a properly sized chain extension.

Installation Tip: For easier installation, some users recommend placing the pin in the freezer overnight to slightly shrink it, and applying light lubrication.

  1. Load and Rating Safety

Working Load Limit (WLL): Never exceed the stamped WLL of the hammerlok.

Match Capacity: Ensure the hammerlok is rated for at least 1.5 times the Aggregate Trailer Mass (ATM) of the trailer.

No Modifications: Do not grind, weld, or alter the shape of the hammerlok.

  1. Safety Considerations for Towing

Avoid Shock Loading: Prevent sudden, jarring, or jerky motions, which can exceed the breaking strength of the device.

Cross Chains: If using two chains, cross them under the coupling, creating a cradle that can catch the drawbar.

Secure Mounting Points: Only attach hammerloks to designated, rated safety chain attachment points on the towbar, not to random bolts or bumper bars.

Summary of Differences

Hammerlok: Used for a more permanent, high-strength connection.

D-Shackle: Often limited to one per safety chain and must also be rated.

Yellow Hooks: Frequently found to be non-compliant or illegal in some regions because they are not properly rated for the same load as a hammerlok or D-shackle.

 

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