i belive that is to cycle coolant.Very cool looking drill press. I especially like the tables built-in-funnel, I've never seen one like that.
i believe it is a 900... one of the castings is cracked on the acme screw holder...need to source onelooks like a 900 with an "industrial" table and table lift. For $40 you have a fabulous deal! Does it have the intermediate pulley?
I have a slightly lesser frills version of that and it's done stellar service for many years, love it to bits.