Re: electric motor forward/reverse wiring?

According to William Wixon <wwixon@xxxxxxxxxxxxxxx>:
i've been trying to figure this one out on my own but can't. i do believe i
need help. i got a reversible motor from harbor freight, mounted it to the
seneca falls star lathe i've been posting about. would like to be able to
run it forward and reverse. have the drum switch from the previous owner.
not sure if i can use it. i made a copy of the wiring diagram in the
motor's manual. the wires illustrated are inside the motor case, have to
reposition them onto the pins inside the motor to get the motor to run CCW
or CW. i'm wondering if i can extend the wires out to the drum switch and
somehow get them to be transposed, black/red - red/black to get the CCW/CW
rotation. i was figuring i'd wire it up to 220 but i guess if it's not
possible to wire it up so it's reversible with 220 i'd wire it 110 instead.

can anyone help/tell me how to do it?

posted illustrations of the 110, 220 wiring and the diagram inside the drum

I see that you have later posted that you believe that you have
figured it out.

If not -- it may take a bit more information. There are fairly
easy ways to set it up for 240V with the information which you have
given and the drum switch which you have, but they have the disadvantage
of leaving one side of the motor hot when it is switched off. There is
a better way to do it. I believe that the black and red wires are the
starting winding (120V only) These are the only two wires which change
place from the forward to the reverse setting.

Terminals (1) and (4) are each connected to *one* of the two run
windings inside the motor where you can't see it.

The other ends of those two windings are white and orange. It
doesn't matter which is which for our purposes. But -- I believe that
the white wire is the other end of the winding connected to terminal
(1), and the orange wire is the other end of the winding connected to
terminal (4).

So -- for 240V operation, they are both connected to terminal 3,
which is not connected to anything inside the motor. It is there just
to allow such things as this.

They are actually reversing the pair of wires for the start
winding by disconnecting them both. However, an alternate way to do
this is to leave one end of the start winding connected to terminal (3),
and alternately connect the other to either terminal (1) or terminal (4)
to select motor direction.

Since you want to do the selection at the switch, instead of at
the motor, this is where terminal (2) comes into play. I would suggest
that you connect black to terminal (3) (along with the white and orange),
and connect red to terminal (4).

Now -- you run to the switch. wires from terminals (1), (4), and
(Also make sure that the motor has a safety ground going to the ground
from the power cord and to the frame of the lathe.)

Now -- the place where we need more information. We need a way
to identify the switch terminals, which you simply drew as:




o o
| |
| |
o o


We need to be able to identify those terminals. In the absence of any
markings on your drawings, I'll simply allocate letters to the
terminals, since we already have numbers on the terminal board in the

So -- using the "Forward" image:




So -- one side of the incoming 240V power connects to terminal (A)

The other side connects to terminal (D) and (F).

Motor terminals (1) and (4) connect to switch terminals (C) and (B)

Motor terminal (2) connects to switch terminal (E).

At this point, you now have a FORWARD/REVERSE switch hooked up
which removes all power from the motor in the STOP position, and which
needs only three wires from the motor to the switch (plus the safety
ground, of course).

Note that you can't "plug" reverse -- that is switch from FOWARD
to REVERSE or vice versa while the motor is spinning. You have to
switch it to STOP, wait for the motor to almost stop, and then switch it
to the other direction. You can only plug reverse three-phase motors,
or (perhaps) repulsion start motors -- which you don't have at the

Good Luck,
Email: <dnichols@xxxxxxxxxxx> | Voice (all times): (703) 938-4564
(too) near Washington D.C. |
--- Black Holes are where God is dividing by zero ---

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