Choosing the Right Hammerlock and Hook Size for Your Trailer

by 4WD-RecoveryGearGeorgeLifting

It is important to know how to choose the right hammerlock and hook size, as making the wrong choice can lead to serious consequences. Here is a quick guide to help you make the right choice.

Government Policy and ADR62 Guidelines

According to government regulations and ADR62, the breaking load limit of a shackle must be at least 1.5 times greater than the ATM (Aggregate Trailer Mass) of the chain. Since the hammerlock and hook are used as shackle replacements, their minimum breaking force (MBF) should exceed the 1.5 times of ATM.

Determining the Minimum Breaking Force (MBF) for Hammerlocks and Hooks

Grade 80 (Yellow Hook and Yellow Hammerlock)

  • The MBF is 4 times the WLL (Working Load Limit).
    • 6mm (WLL 1120kg for lifting) → MBF = 4480kg
    • 7/8mm (WLL 2000kg for lifting) → MBF = 8000kg
    • 10mm (WLL 3150kg for lifting) → MBF = 12,600kg

Grade 100 (Silver Hook, Silver Hammerlock, Black Hammerlock, or Green Hammerlock)

  • The MBF is also 4 times the WLL.
    • 6mm (WLL 1400kg for lifting) → MBF = 5600kg
    • 8mm (WLL 2500kg for lifting) → MBF = 10,000kg

Each hammerlock and hook is marked with its size and grade. For example:

  • 6-8: Size is 6mm, Grade 80, MBF = 4480kg
  • 6-10: Size is 6mm, Grade 100, MBF = 5600kg

Refer to AS3776 standard for more details on Grade 80 and Grade 100 hammerlocks and hooks.

Choosing the Right Size

To determine the correct size, follow these steps:

  1. Check the ATM of Your Trailer:

    • Example 1: If the ATM is 1800kg, multiply by 1.5 → required MBF = 2700kg. A 6mm Grade 80hammerlock and hook (MBF 4480kg) will be sufficient.
    • Example 2: For an ATM of 2500kg, the MBF should be 3750kg. In this case, a 7/8mm Grade 80 (MBF 8000kg) or a 6mm Grade 100 (MBF 5600kg) hammerlock and hook would be appropriate.
    • Example 3: For an ATM of 3500kg, the MBF should be 5250kg. A 7/8mm Grade 80 (MBF 8000kg) or a 6mm Grade 100 (MBF 5600kg) hammerlock and hook would work.

  2. Check the Chain Specification:

    • If using a chain marked 4177-35, choose a hammerlock and hook with an MBF equal to or greater than 5250kg (1.5 times 3500kg).
    • If using a chain marked 4177-25, choose a hammerlock and hook with an MBF equal to or greater than 3750kg (1.5 times 2500kg).

Always ensure the hammerlock and hook meet or exceed the required MBF for safe and compliant operation

    Selecting the correct hammerlock and hook ensures safety and compliance. Make sure to verify the size and grade markings on each item to confirm the MBF matches your needs.

    Weakest Link

    It's important to remember that the minimum breaking strength of the entire setup is determined by the weakest link. For example, if you have a 7/8mm hammerlock and a 6mm hook, the breaking force would be 4480kg because the 6mm hook is the weakest link.

    By following these guidelines, you can ensure that you have the proper setup for your trailer, giving you peace of mind while on the road.

    Setup Suggestions

     

    If you prefer not to calculate, here’s an easy solution:

    Simply choose the setup based on the markings on your chain

    If the marking on the chain shows 4177-35, please select the setup with a title that ends in 35.

    88SL35 7/8mm hammerlock + 7/8mm Hook  ( economy Package)

    HLL35 10mm Hammerlock for tow bar + 7/8mm hammerlock & hook for chain ( hammerlock on tow bar)

    HLH35 hammerlock & Hook combined together  ( hook & half hammerlock on tow bar) 

    HLC35  ( hammerlock on tow bar )

    1086HSS35 Grade 100 hammerlock and Self Locking Hook 6mm 

    1086HLS35 Grade 100 hammerlock and Normal latch hook 6mm

    1086HEH35 Grade 100 hammerlock for tow bar and hook for chain 6mm ( The silver color is designed to match the chain’s color and offers a smaller physical size compared to the yellow hook while still being rated for a 3500kg trailer) 

     

     

    If the marking on the chain shows 4177-10, 4177-16, or 4177-25, please select the setup with a title that ends in 30.

    866HSH30  ( self locking safety hook on chain and hammerlock on tow bar) 

    868HEH30  ( Normal latch hook on chain and hammerlock on tow bar)

    86SHL30 ( self locking hook and hammerlock on tow bar)

    86SSL30 ( Normal latch hook and hammerlock on tow bar)

    • 6mm hammerlock+ 6mm hook suit for trailers with an ATM up to 2900kg
    • 7/8mm hammerlock+ 6mm hook suit for trailers with an ATM up to 2900kg
    • 7/8mm hammerlock + 7/8mm hook suit for trailers with an ATM up to 4400kg

    No worries about choosing the right code, because we've already taken care of it for you.

    Hook & Hammerlock for ATM below 2950kg

    Hammerlock & Hook For Trailer between 2960kg and 4400kg

    G100 Hammerlock & Hook For Trailer of 2500kg and 3500kg  --- One Size Fits All! No need to worry whether your chain is 4177-25 or 4177-35. 

    Trailer Chain Hammerlock and Hook with Shackle For FORD EVEREST! 

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