A hydraulic ball valve is a type of valve used in hydraulic systems to control the flow of fluid. It is a quarter-turn valve that uses a perforated and pivoting ball to control the flow of hydraulic fluid through it. When the valve handle is turned 90 degrees, the ball inside the valve rotates, allowing fluid to pass through or blocking the flow, depending on the position of the ball. Hydraulic ball valves are widely used in various hydraulic applications due to their durability, reliability, and ease of operation.