Why did F3's & Alco's run back to back?

If there were no facilities for turning the engines at the end of a run (turntable, wye track, loop track), the locomotive that had been facing rearward would be facing forward for the return trip and the units would not have needed to be turned. Saved time and money.

MELGAR

@eddie g posted:

Why did F3's and Alco's run back to back rather then both forward?

Many railroads did not have MU connections on the front of their Alco FA units, and lots of EMD F-Units were not ordered with MU connections in thei front nose, either.

Plus, as previously mentioned, the consist did not have to be turned/wyed at the other end of the line, since there was a cab at each end.

Running A units back to back or facing out at each end of a consist was done when diesels were new railroading.   By the 60s and 70s, they ran them anyway and anywhere in the consist.    You note too that the RRs quite buying B units in early 50s for the most part.    As units were rebuilt, many had MU connections added to the noses to make back to back unnecessary.

However, the above reasons are very true then and still are today.    If you see a freight train going buy, not that the locos on each end of the consist are probably facing out.    Not always but most times, they arrange the consist with a cab at each end it seems.

Steam locomotives were typically turned on a turntable at the end of the line (or division point if that is where power was changed out). Multiple-unit diesel-electric locomotives were too long to fit on any turntable so the principal of a cab (control) unit at each end of a locomotive consist was implemented. "B" units, having no control apparatus/seats/doors/windows/ventilation/heat/toilet, were a little cheaper to build so railroads bought a mix of A and B units. By the time so-called "Hood" units were replacing covered-wagon style "Cab" units experience had taught that for flexibility it was worth the extra cost of a control-cab on every unit so cab-less "booster" units were dropped.

In short, multiple-unit locomotive consists usually have a cab at each end facing in opposite directions so that the locomotive is truly bi-direction.

Similar reason the Cuyahoga Valley Scenic Railroad puts an A unit at the front and rear of the train.....no turntable at either terminus, so one heads south and the other heads north.

The Long Island Rail Road had to run their FM C-Liners (eight CPA20-5, four CPA24-5) nose to tail because they bought them without any mu connections (front or rear).  As a result when they needed to run two of them on a train each unit required a crew, and that meant that both units had to face forward.

They were the only cab units built without multiple unit equipment.

Stuart