Want to learn about the main control valve of Hitachi Zx850 and Zx870 excavators? This video is for you! The main control valve of model Ya0031375, with parts 4632971 and 4676374, is an important "heart" component of the excavator. It controls various actions of the excavator and has a huge impact on the efficiency of excavation work. The video will show the details of these parts, whether it is a maintenance technician looking for parts or an owner understanding the equipment, they can get useful information from it.