Elephant Style Running

Early Amtrak... (Pre SDP-40F)...

on three different Chiefs (19/20) in summer of 72...

ATSF ran 5 F-units. A, A (elephant), BB, A (back to back).

ATK wrote:Even in the case of total engine shutdown, the lead unit can still control trailing units in the consist provided that the electrical control system is up and running. 74 VDC can be fed to the dead unit by way of the MU jumper cable or from the locomotive's own redundant battery charger (passenger locos only) via the 480 VAC trainline with the HEP being supplied by a trailing unit. Air pressure of course is supplied from the main res MU connection. Pretty much no different than operating the dead locomotive like a cab car.

Could be a big difference in cold or extreme weather conditions. Maybe
you would like the engineer to shiver or freeze with no cab heat or cab
AC, maybe the batteries go bad and nothing can be controlled from the
lead unit. In cold weather occasionally, the air lines between the two
units can freeze up or an obstruction could occur.
In short, running with the lead unit dead sometimes can be done but much
can and does go wrong and sometimes it can only be a very short time
stop gap solution. Power through the jumper is often not adequate to
take care of all of the electrical stuff on the lead unit.
A dead engine is not a cab car.
Noel Weaver

On the GE units a dead unit will only loose propulsion as long as there is another unit providing HEP. even cab heaters or AC will still work.
on a P32adm the aircompressor even is electric and runs of HEP.

Seems that the elephant-style running on a regular basis didn't begin till sometime in the late-1990's.

Back when the F40's were king on Amtrak, all you ever saw was "back-to-back", and even in the early P40 days, back-to-back was still common.

I would better guess Amtrak is using elephant-style for the mechanical reasons mentioned above, more so than against grade-crossing incidents.

Joe