The first big order of the New York Elevated were fifty 0-4-0 saddle tank locomotives built by Baldwin. After the first tram locomotives built for trials only weighed ten tons, these were considerably heavier, but still small. They had cylinders of 12 by 14 inches and weighed 30 tons when fully loaded.

Deliveries started in 1878 and each locomotive was normally coupled to four bogie cars. They were followed by 50 larger Baldwin 0-4-0ST and by 0-4-4T Forneys. Steam traction ended after electrification of the elevated in 1902 and 1903.

The first New York Elevated Forneys were 45 engines built in 1878 and 1879 by Baldwin and the Rhode Island Locomotive Works. There were two designs of different weight, which later became classes B and C. Like all Forneys, they had two coupled axles, the second of which had no flanges, and a trailing bogie that carried the full load of the supplies.

It all started with the locomotives later known as Class C, of which Baldwin supplied 13 and Rhode Island twelve. The engines delivered the following year became Class B and were slightly lighter with a smaller water supply. These consisted of ten pieces each from both manufacturers.

For the South Side Rapid Transit in Chicago, it was required that the trains with five four-axle passenger cars should achieve an average speed of 15 mph. This was higher than, for example, on the New York Elevated and required extra powerful Forney locomotives. Thus, in 1892 Baldwin delivered a total of 45 of these locomotives, which were primarily optimized in terms of power.

Unusual for a locomotive of this size was that they had a four-cylinder Vauclain compound engine. All cylinders could be supplied with live steam for starting, which ensured high starting tractive effort and rapid acceleration. Thanks to a large firebox, it was possible to use slow-burning anthracite, which reduced smoke emissions and simplified the crew's work.

Another locomotive with the number 46 was also built with a compound engine, but with only two larger cylinders. Since this did not prove itself as a compound machine, it was converted to simple steam expansion and used in switching service.

The performance of the locomotives was fully utilized with a timetable that had two-minute intervals at rush hour. The network was electrified as early as 1898, so the steam locomotives were sold. Many locomotives ended up in industry or logging service, where their mobility was an advantage.