Kimble Electric electric motor wiring help!

I have a old Kimble Electric electric motor, that runs my C&P press, that needs to be wired to the plug & switch. My concern or rather frustration comes from the fact that all that I have is the wiring from the motor which are 4 black wires, not colored.

Each wire is labeled a number, which ranges from 1-4. Wires 1 & 2 are wired together and 3 & 4 are wired together. However, I don’t know which grouping I attach the white wire to and the black wire to for the plug and switch.

Here are the pics. Any help would be great since I cannot find any manuals or info about the motor online since it seems they stopped making them circa 1940’s.

It is a 1/2 horse power, variable speed, 750-2000 RPM, 115-230 volt, a.c. electric motor.

Here is the link for photos of the motor.[email protected]/

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Have a look at this chart.

It shows that for 110, 1 and 2 should be together as well as 2 and 4.


I guess I failed to answer your most basic question. Try one combo and if it runs backwards switch it. Keep in mind that the flywheel should run over the top away from you.

Don’t run it too long in the wrong direction or it will be rough on the brushes in the motor. They tend to wear in directionally and running them the wrong way after they’ve been doing the opposite for a long time will really make ‘em yell at you for mercy.


If you are going to connect the motor to 115 volts, ie. normal household receptacle voltage, the motor leads are paired up correctly. It doesn’t make any difference which pair you connect to the black or white wire. Either way will not cause it to run backwards.

Reversing the wires will not reverse the motor rotation. I realize that is not a concern raised in the original question, just a FYI for future readers of this post.

On these styles of motors where both the stator and armature have coils that are connected to the incoming power supply, the stator is wired directly and the armature thru the slip rings, the relationship between these 2 sets of coils needs to be reversed. Depending on how the motor is wired internally, it could be as simple as wiring 1-3 and 2-4 as an example or you might need to change hard wired connections inside.

The main safety concern I would have is whether the motor is internally grounded or not. If it internally grounded then which pair of wires goes to the black vs white is extremely important. Wiring it backwards would then make the entire motor electrically hot and unsafe to touch.

Since this motor is both 110 and 220 usable it is most likely not internally grounded. Still I would want to double check before wiring and applying power.

To test you need a Volt-Ohm Meter. Put meter in the ohm range and with the motor disconnected from all power and controls and switches see if you have any continuity between each pair of wires and the motor frame.

Any reading less than say 5,000 ohms would indicate either the motor is internally grounded or has insulation breakdown issues. Internally grounded the reading should be less than 1 ohm. A reading from 1 ohm up to 100,000 ohms shows that the insulation of the wiring, coils, connections,etc. has been compromised and failure is close at hand.These ohm readings are just a general shoot from the hip range that I would use as a guide if I didn’t have specific motor spec available.

If one pair of wires to frame shows basically no ohm resistance then that pair needs to be hooked to the black or hot connection.

If this is clear as mud, just ask and I will try to draw up some sketches to illustrate the potential safety effects of different wiring designs.


(A) These motors are not internally grounded.
(B) The armature is connected via a commutator. It is the mechanical adjustment of the brushs that varies the speed by shifting the “neutral plane”.
(C) Most of these brush-shifting motors will run in reverse by moving the speed control past the point where the motor stops. Some have limit stops that prevent you from doing that. In any case, the speed should be kept within the range specified on the nameplate. And, if you choose to run it in the opposite direction, as stated above, it will take a while for the brushes to re-seat so that they arc less.

So, if the motor is not internally grounded, is it a good idea to ground the motor frame, or will this create a short? I have an installation wired for 220 volts and would like to upgrade the wiring to include grounding.

It’s always a good idea to ground the frame of any piece of equipment if you can. If an internal wire should come loose and touch the frame or, in the case of old motors, the insulation should break down either a little or a lot, you won’t get bit if you touch the frame. Rather, the line fuse will blow or the circuit breaker will trip and then you can go search for the problem.

According to the Instructions for Wiring and Care Sheet for Kimble motors, for lower voltage connect one side of circuit to 1 and 2 joined and the other side to 3 and 4 joined. For higher voltage, join motor leads 2 and 3, connect one side of circuit to 1 and other side to 4.