This yellow tool appears to be a pneumatic air leg rock drill. [1]
Function: It is designed for drilling rock in mining, railway construction, or water conservancy projects.
Mechanism: These machines typically use water flushing for cooling and cleaning, and feature a back head control for rotation and pusher leg operation.
Variants: While this is a pneumatic model, similar-looking tools include internal combustion gasoline rock drills, such as the YN27C model. [1, 2, 3, 4]