The shaft with code K 28025 is specifically designed to support and align the main rocker arm (K 28005) within the ZV40/48 engine. This robust shaft acts as a pivot point for the rocker arm, allowing it to transfer motion from the camshaft to the valves with mechanical precision. Built from hardened, wear-resistant steel, it must withstand constant mechanical stress and thermal cycling. Its proper function is essential for maintaining accurate valve timing and reducing wear in the valve train, directly affecting engine efficiency and reliability over time.