corrosion and protection of materials

(6) In the oil exploitation process, a pumpjack shown in Figure 4 is used to mechanically lift oil out of the oil well. It does that via a prime mover which supplies rotational energy to the crank and results in the cyclic pumping movement of the horse head. Over a period of time, one specific type of corrosion occurred. Horse Head Prime Mover MONONE Crank Figure 4 Using labelled diagrams, demonstrate the mechanisms for the type of corrosion that has occurred. Do state the type of corrosion in your explanation