disclosed herein is a coupling assembly for use with a gooseneck trailer . the coupling assembly comprises a height - adjustment device and a coupler mechanism . optionally , the coupling assembly further comprises a locking assembly and a friction fit assembly . the height - adjustment device within the coupling assembly uses a load - bearing pin to concurrently and / or simultaneously perform two functions , namely permitting adjustablility of the coupling assembly and bearing all , or substantially all , of a vertical load provided by an attached gooseneck trailer , any trailer accessories , and any trailer contents . because the load - bearing pin bears all , or substantially all , of the vertical load by resisting the shear force , conventional reliance upon a friction force to bear the vertical load is substantially eliminated . a tongue on the gooseneck trailer connects the gooseneck trailer to the coupling assembly and the coupler mechanism on the coupling assembly secures a ball mount on a towing vehicle to the coupling assembly . as such , the gooseneck trailer and the towing vehicle can be coupled and uncoupled . the locking assembly on the coupling assembly alternatively locks and unlocks the coupler mechanism . the friction fit assembly on the coupling assembly inhibits relative side - to - side movement between an inner and outer member within the coupling assembly .