here is what the originals looked like, above, the mocked up prototype, below, a finished working replica for the 1914 model t. Made by Randy Shelton, a Ford powertrain engineer who is restoring the below truck
When Otto Neumann and August Fruehauf invented the semi-trailer in 1914, they created a version of a 5th wheel coupling which they used until 1916. Then they adopted an improved version of the fifth Wheel offered by the Martin Rocking Company in Massachusetts.
above and below, the Martin 5th wheel
which was improved on until it became the common and ordinary hitch you're used to seeing