3.5t Al-ko Marine Coupling

$106.16 inc GST

SKU: CM232M Category: Tag:


3500kg Al-ko Marine Coupling.

  • Hole spacing is 182.5mm x 55mm – 4 x 13.5mm holes.
  • The Al-ko marine coupling complies with Australian Standard 4177.3
  • The Marine Coupling is rated at 3500kg.
  • The adjustment nut on the head of the coupling is a 1/2″ BSW thread.

This nut prevents the Marine Coupling jumping on the tow-ball and creates and tight fit by removing slop that can occur through wear.

Lightweight boat trailers use this press metal coupling.


To properly adjust this nut

  • Put pressure on the Marine Coupling head so that it is firmly on the tow-ball.
  • Loosen the nut.
  • Screw down the thread so that you can feel it touch the top of the tow ball.
  • Now tighten the locking nut being careful not to unscrew the threaded screw.

One final thing, your coupling weight when attached to

  • Tandem trailer should be around 5% to 7% of your total load.
  • Single Axle trailer should be 7% to 10% of your total load.

Your coupling should now be tight and ready to tow.

ADR Requirements


2.1.     ‘Ball Couplings’ intended for towing trailers up to 3.5 tonnes ‘ATM’ must comply with Australian Standard 4177.2 – 1994 “50 mm Towballs” or as amended from time to time.


3.1.    The coupling body of a 50 mm ‘Ball Coupling’ intended for trailers up to 3.5 tonnes ‘ATM’ must comply with Australian Standard 4177.3 – 1994 “Coupling Body for Ball Couplings” or as amended from time to time.

Vehicle Standards Bulletin VSB1

Sure, there are cheaper couplings on the market. We buy and recommend only the best products for your investment dollar.

Finally, if your boat does a lot of highway miles, be sure to read this article on u-bolts.

In my opinion, a lot of trailer and caravan accidents are caused by u-bolts that have never had their final adjustment. Check your nuts, you may be surprised.

The electric equivalent coupling can be found by clicking this link.

Couplemate Trailer Parts sells only the best quality 3.5t Al-ko Marine Coupling and caravan spare parts throughout Australia.

Customers are welcome to either pickup or take advantage of our low freight rates. Express shipping to Melbourne, Sydney, Brisbane, Perth, Adelaide, Darwin, and Hobart.

We also ship products to New Zealand via Australia Post Air Express.

© Steve Wotherspoon January 22, 2018. Images and text may be copied, provided a link back to the copied page and the source is displayed where the content or image is located.

Additional information

Weight8 kg
Dimensions40 × 20 × 10 cm


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