....
Karl, can you give a bit more information re. upgrade to 3-Phase and VFD
control? I helped a friend go through the "electrics" on a 1964 Monarch
10EE. We repaired and restored the original DC speed control function.
This involved a lot of labor and troubleshooting time plus the cost of a
new ( nominal $500) vacuum tube. Please elaborate a bit on the difficulty
and cost of replacing the DC motor with 3-Phase and VFD speed control.
How difficult was it to integrate into the Monarch's transmission? Was
there a space problem? Did you restore the original 10 HP capability of
the Monarch?


Y^ou have a choice on which way to go.

1. Put in a 10 hp. three phase motor and toss the step down tranny.

2. Put in a 5 hp. three phase motor and keep the step down tranny.

I went with option 2. Completely tear the field windings out of the old DC
motor, cut the armature shaft just before the commutator. Mount a new 5hp
motor inside the shell of the old motor, there's plenty of room. Connect new
motor to old shaft with a roller chain coupling. Alignment is pretty touchy
here.



For control, tear out the old rheostat assembly and replace it with a 2K ohm
pot. Connect pot to VFD. Tear apart the old rocker shift assembly for
forward/reverse. Connect contacts to VFD forward and reverse. Done this way,
the operator can't tell its not an original 10EE, controls are identical.



I spent $25 on the 3 phase motor, $20 on the pot, got the roller chain
coupling out a the scrap heap, and maybe $300 on the VFD drive. Of course,
my time to do all this was free.

Karl