For the operation of the railway lines Breda - Tilburg (opened on October 5 1863) and Harlingen - Leeuwarden (opened on October 27 1863), the SS ordered four steam locomotives with the wheel arrangement 1'A1' (2-2-2) from Beyer, Peacock & Company of Manchester, England.

The locomotives were equipped with a boiler with a maximum working pressure of 6.2 kg/cm2 (88 psi).

With the expansion of both railway lines, another 6 locomotives were ordered in 1866, which were given the numbers SS No.

These locomotives were fitted with a boiler with a maximum working pressure of 8.3 kg/cm2 (118 psi).

255-260 received new boilers, with the maximum working pressure remaining the same.

When the fleets of the HSM and the SS was merged into the Dutch Railways in 1921, the only remaining locomotive with the wheel arrangement 1'A1' was given the NS number 501 and the locomotives with two driven axles converted to wheel arrangement B1', the NS numbers 601–606.

Whether the 501 actually carried this number is uncertain, as the locomotive was not used since April 1921 and the physical renumbering took place in December.

501 is the only steam locomotive with only one driven axle that has survived into the NS era.