Timing belt pulleys are used to connect and synchronize the rotation between two shaft systems. These Pulleys are designed so that the teeth of the belt enter and leave the grooves with negligible friction. All Pulleys, stock and made-to-order, have minimum tooth-to-groove clearance(backlash).
The Timing Belt is the belt that controls the camshafts in your engine, opening and closing valves at just the right time for smooth operation. The timing belt has teeth that turn the camshaft in time with the crankshaft. Some cars and trucks use timing chains or gears, which are more durable.