Dr Zarkoff Wrote:
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> Originally A-B-B-A FTs had rigid drawbars like
> this, but this scheme didn't last long. Think of
> cow/calfs as being two switch engines, only one of
> which has a control cab.

The FT Series diesels, as originally designed and built by EMD, only had engine starting batteries in the A - Unit; this required at least an A - B set.
Santa Fe ordered some FT's as A - B - B - B sets to try and dodge the issues of " a fireman required in every cab." This is also why many RR's labeled an entire FT set as one unit ( " Northern Pacific 6000" ), with small A - B - C - D suffixes for mechanical dept. reference only. ( NP would later re - number their FT's in a horsepower - based 5400 series. ) Southern Rwy used drawbars between all 4 FT-Units in a set, while Santa Fe would both order a few new FT sets with steam boilers for passenger service, AND install boilers in existing FT B - Units. No Santa Fe F - Series Cab unit ever had a steam boiler. Lackawanna ordered 3 - unit FT sets, with no overhang on the B - Unit; these were referred to as FTSB ( short B - Unit ).
The FT's were a game - changer, yet they had manual transition & manually operated radiator fans, and only convection - type dynamic brakes without a fan to blow cool air across the grids.