Please, what is the purpose of the drum switch? Safety, convenience, speed control, etc.?

jbartos, it's on a lathe with a 1.5hp, 110V, Single Phase. I've been searching for a diagram -- to no avail, the little "sticker" that comes with the New switch(An "RS-1A" by the "Relay & Control Corp.", replacing an Allen-Bradley Unit) is a little confusing --- it doesn't Clearly show where the Leads from the motor should connect to which terminals, OR same for the Power Supply line. Do you know of a site where we could view such a diagram, Jbartos??
------Michael

Jbartos, the switch on the lathe - is, as usual for fwd & reversing the direction of the Headstock(chuck).--Michael

Suggestion: Reference:
1. McIntyre R. L. Electric Motor Control Fundamentals, Third Edition, MgGraw-Hill Book Company, 1974
Reference 1 describes three-phase motors of squirrel-cage type reversers by drum controllers.
Also, it shows the single phase motor reversal switch using Double Pole Double Throw (DPDT) switch. The start winding is controlled by the DPDT where phase and line are connected to the center (off) terminals (two), the start coil is connected to one direction terminals (two), and two conductors from the start coil are crossing to the reverse rotation two terminals inside the DPDT. Simple precaution is that the motor shall come to the rest before switching in the reverse. Also, suggest to contact or search
http://www.thomasregister.com