The class B15 was a 4-6-0 introduced by the Queensland Railways in 1889. The B in the designation stood for three driving axles, while the 15 was the cylinder diameter in inches. It was a mixed traffic locomotive like the B13, but more powerful. After the first 15 had been built by Nasmyth, Wilson & Co., more followed from three other manufacturers. In total 92 were built for the QR and six similar locomotives were acquired from the Chillagoe Railway & Mining Co. in 1919. Due to damages on the rails, one was fitted with drivers of 45 instead of 36 inches in 1900. Over the following three decades, most class members were also rebuilt in this way. They were used in the Cairns area during most of their careers and numbers 290 and 299 were later preserved.