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The E-15 of course has more speeds, for more flexibility, higher top speed. It
also has larger tires.more important, IMHO, is the fact that the E-15 has a more
robust traction motor.More continuous power output, more
endurance.
Since the later E-12 models
have a PM traction motor, putting it to work with the E-15 controls would
provide no advantage.
The E-12S is essentially a "decontented" E-15. first, it has smaller
tires. It has a wound field motor, a plus IMHO, over the later ones, but of
course has no sophisticated field control.
Both the E-12S and the
stablemate E-15 of that era have the then 'state of the art'
SCR / UJT control system that never really impressed me from a reliability
stand point . Add to that the problematic field reversing directional control,
and you have a system that would not be my first choice for a tractor that sees
heavy use, year 'round.
So, the wound field
motor from the 'S' model is a 'plus', but the armature reversing control used in
the later models is again IMHO a durability 'plus'.Looks like a dead heat to
me.
If
I've stomped on anyone's toes, I will apologize. These "IMHO" statements
are based on the observations that I've made over the past twenty or so
years of servicing these units.
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