What prints or drawing were/are you working from? Presumably you bought parts for self assembly?
That is obviously the main contactor, the two white wires on #5 is the overload contacts.
The push button usually engages a start capacitor, as soon as it is up to run, then the P.B. is released, but there are other methods, some use a timer.
Here is a drawing that may help somewhat in the MetalWorking drop box.
metalworking.com - /dropbox/_1998_retired_files/
Look for Fitch Williams files FRW- etc.