The KR group has many wagon types. The class developed in the late 1950's for transporting rails, probably for the standard guage project 1957-1962.
Up to this time rails were carried on general freight wagons: _Q__, _QR_ and early in the 1900's, _QN_ wagons. These wagons were suitable for rail lengths about 40' but when rail lengths increased, different wagons were required.
The first KR wagons were twin coupled _I__/_IA_ wagons. When rails lengths went longer, KR wagons were semi-permanently coupled into blocks of about 8 - 10 wagons. Each rake had a bulkhead KR at each end. To unload the long rails, small cranes were fitted to every third or fourth wagon. A hinged jib piece extended the crane reach beyond the wagon edge.
Some of the I / IA wagon conversions were stretched for conversion.
Some later type KR wagons were semi-permanently coupled steam engine tender underframes.
KR numbers were 124 - 189, 191 - 318. The number group was established as part of the K number group at 1956.