French Northern Railway No. 2.641 to 2.675

The first series-built compound Atlantics of the de Glehn system were the locomotives of the French Nord, which were delivered from 1900. They were designed to maintain the speed of 200-tonne express trains at 100 km/h on 0.5 percent steep gradients, something the previous 4-4-0 machines could not achieve. Initially the prototypes 2.641 and 2.642 were created, as well as 33 series machines.

The de Glehn system, which later became widespread, especially in France, had separate valve gears and reversers for the high and low pressure cylinders. By keeping the wheel base of the driving axles as short as possible, the length of the coupling rods and the moving masses could be reduced. The tenders initially had a limited capacity due to the length of the turntables, but later tenders with up to 37 m³ of water were used.

They were able to easily exceed the required performances and reached speeds of up to 155 km/h during test runs. Approval was initially given for 120 and later 130 km/h and average speeds around 100 km/h were not uncommon. They later received superheaters and Lemaître blastpipes and became the 2-221 A at the SNCF. Their general design served as a model for many other locomotives.