Filter apparatus with dual drive loops

In an improved filter apparatus including an upper tank for holding dirty liquid and having a perforated plate, a lower compartment beneath the perforated plate for receiving liquid from the upper tank through the perforated plate, a permanent filter belt for filtering particulate from the dirty liquid and arranged in a first circulating path across the perforated plate, and a drag conveyor having a series of spaced apart flights and arranged in a second circulating path across the perforated plate such that the permanent filter belt is positioned between the perforated plate and the flights of the drag conveyor across the perforated plate, wherein the improvement comprises:

• a first pair of spaced apart drive loops attached on respective sides of the permanent filter belt;
• a second pair of spaced apart drive loops attached on respective sides of the flights;
• and
• a driving mechanism operable with the first and second pairs of drive loops for indexing the permanent filter belt and the drag conveyor along the respective circulating paths such that a fresh segment of the permanent filter belt is periodically indexed over the perforated plate while a dirty segment of the permanent filter belt is being cleaned and the flights of the drag conveyor are periodically indexed to carry away accumulated particulate filtered by the permanent filter belt.