I would like to use two double wound field motors from two old SD40’s to make a two motor unit and tethered dummy since the motor trucks have no pickups. How do you wire a three position e-unit to the motor? It originally came with an electronic e-unit which Lionel informed me did not have the capacity to handle two motors.
Dallee caries a 4 amp electronic E-unit. You may want to check this out before using a mechanical one:
Red wire to pickup, yellow and blue wires to brushes, green wire to field, other end of field and frame of e-unit to wheels.
If there is no red wire on the e-unit, use the end of the coil that is connected by a short wire down to the fingers to connect to the pickup. Sometimes instead of yellow and blue there are two yellow wires.
Be sure to mount the e-unit vertically unless you have one of the rare ones with a spring inside it.
The field coil, as you know, has two windings. Lionel says to use one of them and leave the other unconnected. However, you can get a somewhat lower-speed and higher-torque operation by using both windings in series, leaving their common terminal with no connection.