What is the function of a check valve in a hydraulic accumulator circuit?

In a hydraulic accumulator circuit, the primary function of a check valve is to prevent backflow of hydraulic fluid from the accumulator back to the pump or reservoir. An accumulator is a pressure storage device that stores hydraulic energy. It allows a hydraulic system to meet peak demands exceeding the pump's capacity or to maintain pressure during periods when the pump is inactive. The check valve is typically placed between the pump and the accumulator, allowing fluid to flow from the pump into the accumulator to charge it. However, it prevents the pressurized fluid stored in the accumulator from flowing back towards the pump when the pump is not operating or when the pressure in the system drops below the accumulator's pressure. This ensures that the energy stored in the accumulator is available for use when needed, such as during a sudden load demand or to compensate for leakage. Without the check valve, the pressurized fluid would simply flow back to the pump or reservoir, rendering the accumulator useless. For example, in a hydraulic braking system, an accumulator might be used to provide braking power in case of pump failure. The check valve would prevent the stored pressure from bleeding back, ensuring that the brakes can be applied even if the pump is not functioning.