Hi Scott,
Just noticed your thread, and wanted to see if I could help. Interestingly, not long ago I restored a 1/2 HP Delta motor very similar to yours, to power an old Delta wood lathe I'm restoring. It was originally wired wrong, and so I had to figure out the right way to wire.
These are basically simple motors, consisting of two "run" windings, and one "start" winding. The start winding is wired in series with the centrifugal start switch and capacitor. To run on 120 volts, the two start windings are wired in parallel across the two power legs, and the start winding circuit is wired across the line as well. The first diagram shows this. It's like a 3-rung ladder, with 2 rungs powering the motor, and 1 rung for starting. Note that the starter circuit is switched out of the circuit when the motor gets above a set speed.
Even without color codes or wire numbers, you can pretty easily figure out which wire does what by checking resistances across pairs of leads. The ohms values shown on the schematic are from my own motor, but yours should be close to this. There will be two windings of fairly low resistance, and one winding of a higher resistance. The winding with the higher resistance is the start winding. Note that with the motor at rest, there will be no continuity across the start rung, as the capacitor will normally read as "open" under a DC continuity test.
The thing to watch out for is that the two "run" windings must be wired in phase. In your case, based on the diagram that you found from a different motor, this means that the red and green wires should be connected together, and the black and yellow wires should be connected together. In the event that you're not sure which way is in phase, you can run the motor with only one run winding connected, then run it with the other winding connected. If the motor turns in the same direction each time, then the run windings are in phase. If not, then the run winding connections need to be reversed.
The reversing drum switch you have is a fairly simple one. It is interposed between the line cord and the motor as shown in the second diagram. The two sides of the line are switched on and off with the two outside sets of contacts, while the inside set of contacts connects to the starting circuit. Reversing the current flow through the starting circuit is what reverses the motor. (The numbers 1 thru 6 on the switch terminals are arbitrary, and won't necessarily correspond to your switch.)
The schematic for the switch shows it in both the forward and reverse modes. The switch contactors are shown in red. You will need 4 conductors to connect the switch to the motor, plus a ground wire that connects the switch housing to the motor frame. Also, the line cord should have a ground conductor that connects to the switch housing.
Good luck with your project, and let me know if you have any questions.
Paula
