Baldwin Locomotive Works built an experimental compound expansion 4-10-2 in 1926, but since the weight and length of this engine was too much for all but the heaviest and straightest track and compound steam locomotives had already lost favor on United States railroads, its demonstration runs failed to generate interest and no more were produced.

In 1912, after the establishment of the South African Railways, the surviving unmodified NGR locomotives were designated Class H.[1][2][7] In 1901 and 1902, towards the end of the Second Boer War, the Imperial Military Railways also acquired 35 Reid Tenwheeler locomotives from Dübs and Company and Neilson, Reid and Company.

Only sixty locomotives of this wheel arrangement were built for domestic service and all but one were constructed as simplex three-cylinder engines.

As technologically innovative as Baldwin's 4-10-2 was, however, it was outmoded when built since compound steam locomotives had already lost favor in United States railroading.

The three-cylinder feature on these locomotives gave them a distinctive sound at work, described as a "hop, skip and jump rhythm".

[9] While the SP engines could operate only on relatively straight and heavily built mainlines, their long service lives of between 28 and 30 years proved that they were good locomotives.

It was reported that such failures created such great pounding on the rails that railroad housewives along the line "complained of crockery cracking when a defective 4-10-2 rumbled past their homes".