The pivots appear to be centered between two of the axles. Illustration is of a 30" gauge Kitson-Meyer built in 1911 for the Antofagasta & Bolivia Railway.
Antofagasta is a port on the Chilian Pacific coast in the northern part of the country. This was a company organized by British investors; and it was a concession granted in the 1870s by the Bolivia government to the mining company. Chile took possession of this portion of Bolivia during the War of the Pacific (1879-1884) and confirmed by a treaty in 1904.
The image is a scan of a page of the book
Kitson Meyer Articulated Locomotives by Donald Binns
Brian Norden