4-6-4-4

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WheelArrangement 4-6-4-4.svg
4-6-4-4 wheel arrangement
PRRQ1p8.jpg
The PRR Q1 6130 - the only locomotive with this wheel arrangement

In Whyte notation, a 4-6-4-4 [1] is a railroad steam locomotive that has four leading wheels followed by six coupled driving wheels, a second set of four driving wheels and four trailing wheels.

Other equivalent classifications are:

The sole example of this arrangement was the PRR Q1. This locomotive was essentially a prototype in the development of the PRR Q2, a 4-4-6-4.

References

  1. "4-4-4-4, 6-4-4-6, etc. "Duplex Drive" Locomotives in the USA". steamlocomotive.com. Retrieved 20 May 2025.