Filter media rewinding mechanism

An improved filtration apparatus using a filter media to filter contaminants from a dirty liquid, the filtration apparatus comprising:

• an upper tank for holding dirty liquid and having an imperforate end wall and a perforate floor, and a lower filtrate compartment beneath the floor for receiving liquid from the upper tank through said perforate floor;
• a guide roller over which filter media is moved downwardly and positioned to guide the filter media along the end wall and along the perforate floor of the upper tank for filtering out contaminants as the dirty liquid is received from the upper tank into the filtrate compartment;
• conveyor means for indexing the filter media to effect emergence of the contaminated filter media from the upper tank and to begin to increase the total length of said contaminated filter media emerging from said upper tank;
• a filter media take-up mechanism for taking-up filter media;
• and
• a rotatable idler roller assembly including a support and an idler roller mounted thereon;
• said idler roller guiding said filter media and being vertically movable along said support in a range of motion arranged to take up the increased length of said contaminated filter media and to provide tension to the filter media as the filter media is indexed from the upper tank by the conveyor means;
• said rotatable idler assembly also including upper and lower limit switches mounted to said support as upper and lower limits of said range of motion;
• said idler roller actuating said lower switch to start the take-up mechanism when said idler roller reaches a lower limit of its vertical range of motion and said idler roller actuating said upper switch to stop the take-up mechanism when said roller reaches an upper limit of its vertical range of motion.