Coupling arrangement

A coupler for a coupling arrangement for a heavy haul rail wagon, the coupler comprising:

• a body;
• and
• a knuckle movable relative to the body, the knuckle including a tail rotatable relative to the body about a knuckle axis a closed position and an open position, the tail of the knuckle including a single upper lug and a single lower lug configured to respectively engage a corresponding single upper lug and a single lower lug of the body, the knuckle further comprising a protruding portion that is engageable in use with a complementary knuckle of a coupler for an adjoining rail wagon when in the closed position;
• the body comprising at one end a head portion including an interior wall defining an interior cavity for receiving the tail of the knuckle and having the corresponding single upper and lower lugs extending therefrom, and a butt portion at an opposing end of the body for engaging a yoke;
• the coupler further comprising a lock disposed in the interior cavity and moveable from a locked and an unlocked position, and when the lock is in the locked position, the knuckle is retained in the closed position and when in the unlocked position, the coupler is adapted so that the knuckle is moveable to the open position without use of a kicker housed within the interior cavity;
• and
• wherein the interior wall defines a generally T-shaped interior cavity including a cross-bar cavity for receiving the lock and a stem cavity for receiving the tail of the knuckle and wherein the corresponding single upper and lower lugs defined by the interior wall respectively extend from an intersection of the lock cavity and the stem cavity to an end of the stem cavity,
• wherein in use load transfer within the coupler is accommodated through engagement of the tail with the body within the stem cavity including by engagement between the single upper and lower pulling lugs of the knuckle and the corresponding single upper and lower pulling lugs of the body, and the body is configured such that the interior wall defining the stem cavity and extending to the exterior of the body is continuous, wherein the interior wall does not include a kicker cavity, and wherein the load path from each corresponding single upper and lower pulling lug is non-convoluted so as to be substantially devoid of areas of significant stress concentration.