the head is variable speed 110v motor. managed by pullys and belt. up top is a lever to turn and control speeds. the belt expands / rides up and down the sleeve. it also has built in power down feed.also notice where the location of the handle is to raise the fixed head / column from the base. the hole column rises. I can,t find an early rf30 or Asian mill drill like this to compare it with. this is a 1983 model. i can,t help but think they used that top from a another model at that time to enable the ad ons.clearly its factory.the paint is original and I have the owner manual. so my search is to find what else/ or machine thay also used that top on also.if that makes any sense. I have found fixed head mill/drills where the hand crank is located there. also lathes with that style speed control.clausing if I remember correctly but not on a mill. and obviously the vfd became more acesable in the mid 80s making a contraption like this obsolete.