plural of 4-4-2

Under the Whyte notation system, a duplex steam locomotive that has six coupled leading wheels in a leading truck, two sets of four driving wheels, and a six coupled trailing wheels in a trailing truck.

Under the Whyte notation system, a duplex steam locomotive that has four leading wheels in a leading truck followed by four coupled driving wheels, a second set with six coupled driving wheels, and four trailing wheels in a trailing truck.

Under the Whyte notation system, a duplex steam locomotive that has four leading wheels in a leading truck followed by six coupled driving wheels, a second set with four coupled driving wheels, and four trailing wheels in a trailing truck.

Under the Whyte notation system, a Mallet-type locomotive with no leading truck, two sets of four driving wheels, and no trailing truck.

plural of 4-4-6-4

plural of 6-4-4-6

Under the Whyte notation system, a Mallet-type locomotive with no leading truck, two sets of four driving wheels, and two trailing wheels on a trailing truck.

Under the Whyte notation system, a Mallet-type locomotive with two leading wheels on a leading truck, two sets of four driving wheels, and two trailing wheels on a trailing truck.

plural of 2-4-4-2