[1][3] The locomotives used Allan valve gear and were equipped with dust covers to protect the motion from wind-blown sand in the Namib Desert.

The "Hb" classification identified the locomotive type as the second class to have been built for GSWA by Henschel.

[1][4] Photographic evidence show that some of these locomotives were eventually permanently converted to tender engines by removing their side tanks.

During the First World War, the former German Colony came under South African administration and the railways in GSWA came under control of the Union Defence Forces.

They retained their German Colonial Hb classification and engine numbers while in SAR service.