What is the King Pin Diameter on the Bulldog Gooseneck to 5th Wheel Hitch Adapter


I am wanting to pull my gooseneck trailer with my semi tractor. Is the kingpin dimentions correct for a semi fifth wheel?

Expert Reply:

The standard king pin dimension for a semi-trailer is 2 inches diameter, where the fifth-wheel jaw wraps around the king pin. I went out to the etrailer.com semi-trailer on our lot, see link, and produced a short video showing both of the king pins in close proximity to each other for you to see.

The king pin on the Bulldog Gooseneck-to-5th-Wheel Trailer Coupler Adapter, # BD0289580300, is an industry standard 2 inch king pin and will work in a semi-tractor fifth-wheel hitch, as long as the height adjustment is adequate for towing the trailer.

If your gooseneck trailer already has a 4 inch inner diameter tube welded on the tongue and a removable gooseneck hitch, you could use the Gooseneck to Fifth Wheel Trailer Adapter, # 2085205, on your trailer.

expert reply by:
Robert G

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