What component is used in a closed loop hydraulic circuit to replenish fluid lost?

In a closed loop hydraulic circuit, a charge pump is specifically designed to replenish the hydraulic fluid that may be lost during operation. It works by drawing fluid from the system reservoir and pushing it back into the closed circuit, ensuring that there is always an adequate supply of hydraulic fluid for the system to function properly. The charge pump plays a crucial role in maintaining the pressure and volume of fluid in the system, which is essential for the reliable operation of hydraulic components.

The other components mentioned serve different roles within a hydraulic system. A relief valve is used to prevent excessive pressure by diverting fluid when the pressure exceeds a certain limit, while a pressure reducing valve helps to maintain a lower pressure in part of the system. An accumulator stores hydraulic fluid under pressure, allowing it to release hydraulic energy when needed, but it does not replenish fluid in the system. Thus, the charge pump is the correct answer as it directly addresses the need for replenishment in a closed loop hydraulic circuit.