F3 A-B set considered one or two engines ?

[Anonymous]

Did the railroads consider an F 3 A-B set, for example, as one or two engines for numbering purposes, etc. ?

[daveklepper]

The original FT 4-unit sets were often assigned one number, with -A, -B, -C, and -D for the different units. Many railroads did continue this practice with F3 A's and B's, two units with the same number, but by then, especially since couplers connected most F-3 A and B units, with any B unit used with any A, separate numbers were used by most.

[chad thomas]

I belive the reason they were considered to be one unit was so the unions didn't require a complete crew on each engine (B units excluded) when steam dissapeared.

[eolafan]

Some very early FT models had A and B units permanently connected by drawbars and were only operated in matched and permanent sets which could only be seperated by mechanical department personnel for servicing, etc. This practice ended rather quickly once the railroads and EMD realized the versatility of the F unit diesel.

[CShaveRR]

Two engines, definitely.

(Each delivered 1500 horsepower from 16 cylinders.)

Now, if you're talking locomotives, it depends on the railroad, and the time frame. Drawbars on the early units that had them were eventually replaced by couplers and the units became separated from their original partners. Someone mentioned the original FT units, which were considered to be a 5400-horsepower locomotive (or 4050, for the railroads that got A-B-A sets instead).

C&O, when it got its first cab units (F7s) in about 1949, numbered cabs and boosters in separate series. But they were run as three-unit sets through most of the 1950s--if you knew the number of one of the units, you could usually determine the number of the other two.

[Dutchrailnut]

Any Mu'ed engine consist is considered one engine for rules purposes.
A hostler can move engines as long as their single or fully MU'ed.
A locomotive on a freight train assumes the identity of lead unit and entire engine consist is refered to as the number uused for that first locomotive.