In 1925, the South African Railways placed a single experimental Class FC Modified Fairlie articulated steam locomotive with a 2-6-2+2-6-2 Double Prairie type wheel arrangement in service.

Collins DSO, Chief Mechanical Engineer of the South African Railways (SAR), was authorised to experiment with a modified type of Fairlie locomotive.

It was similar in appearance to a Garratt, but with the boiler, cab, coal and water bunkers all mounted on a single rigid frame which extended almost over the full length of the locomotive.

This resulted in a more efficient boiler and also distributed the weight of the engine over a greater length than was obtainable with an orthodox Double Fairlie design.

It was claimed that the Modified Fairlie arrangement reduced the wear between wheel flanges and rails and that the distribution of the loads on the axles as fuel and water was expended was less variable than could be obtained with the Garratt design.

Hence, also, the experimental Modified Fairlie's Class FC designation, skipping the FA and FB classifications which were never used by the SAR.

The heavily laden overhangs beyond the pivots also led to metal fatigue due to its tendency to oscillate up-and-down.

The pivot bearings were also subject to quite rapid wear, since they carried a considerable additional load compared to those on the Garratt as a result of the water and coal bunkers which were mounted on the long main frame instead of on the engine units.