The pump is connected to the engine, and it pumps fluid (standard oil) to the torque converter. The turbine is linked to the gearbox, and it spins when the fluid with the pump hits it. A nasty transmission filter will induce your gears to grind on each other as well https://filter-gearbox90172.ampedpages.com/not-known-details-about-filter-gearbox-61046531