The shaft drive grit collector mechanism is mounted on a walkway which spans a wide shallow tank. This chamber is designed as a constant-level, short-detention settling tank for grit. The influent stream enters one side of the tank where adjustable flow deflectors create more uniform flow distribution across the tank. The flow exits the tank over a fixed knife-edge weir opposite the inlet. The rotating rake arms are designed to slowly scrape the settled grit outward into a collection hopper where it is removed by a grit classifier. The inclined grit classifier washes and dewaters the grit while lifting it from the hopper to a higher point of discharge.