Draw bar, chains, couplings

Drawbar to be securely attached to a ‘substantial portion’ of the trailer.  Longitudinal tension and compression (Newtons) 1.5 x 9.81 x ATM (kg).  That would suggest to me that it needs to be able to withstand the towing vehicle accelerating at 1.5 gravities.  Having owned a ZZR1100, and knowing that it was only JUST able to reach 1G of acceleration, I know that that’s quite a bit of force :)

Transverse thrust, and vertical tension/compression is (N) 0.5 x 9.81 x ATM (kg).  Tranverse thrust, what’s that?  Vertical tension/compression? that’d be up and down on the towbar as you go over bumps?

Well, basically what those two are saying, is the drawbar needs to be REALLY WELL ATTACHED.. :)   I’ll likely have mine very securely welded below the floor frame and front and back (and any other cross-braces I put in the floor..)

Chains.. Well, under 2.5 tonne ATM, must have one safety chain complying with AS 4177.4-1994 or AS 4177.4-2004-Part4  The attachment point for the chain should not come into contact with the road when the trailer is disconnected.   ‘Safety chains, which ave the mechanical T grade property, are not suitable for welding’.  Do we HAVE to weld? Or is a shackle between trailer and chain ok?  Find out!

Coupling – Must have  quick release coupling which is designed to be used without tools.  It must be positive locking with provision for a second independant type.  Coupling to be mounted so that the height of the center of the body of the coupling is 350-420mm above the ground when loaded.   Hmm, check the height of my motorcycle’s tow-ball!.  Coupling to be marked in accordance with ADR62/01 and ADR62/02.  This is:

  • The manufacturers name or trademark.
  • The mark ‘50’ (50mm ball)
  • Maximum rating for the coupling (750kg)
  • a code to indicated serial, batch, production date, or similar
  • ‘DO NOT WELD’, if made from non-weldable material
  • ‘WELD ONLY’ if the coupling is to be attached by welding only.

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