Abstract

An indexable filter web is advanced downwardly into and then upwardly out of a pool of dirty coolant by a perforated flexible belt. Rotatable wheels shape the belt and the web into a circular configuration with the bottom of the web defining the bottom of a clean coolant pool located inside of the web and within the dirty coolant pool. The pressure of the coolant in the dirty pool forces the dirty coolant through the web, the coolant being filtered by the web and flowing into the clean pool for subsequent discharge into a clean tank. The sides of the clean pool are defined in part by stationary ring-like elements which coact with the side edges of the belt to form grooves for receiving the side margins of the web. The pressure of the dirty coolant forces the side margins of the web into the grooves and causes the side margins of the web to seal themselves to the ring-like elements so that coolant is prevented from flowing into the clean pool without passing through and being filtered by the web.