ANS:B - a cylinder and a plunger.

A hydraulic accumulator typically comprises of a storage device and a control valve. Here’s an explanation:

1. Hydraulic Accumulator: An accumulator is a device used in hydraulic systems to store hydraulic energy in the form of pressurized fluid. It consists of a container (storage device) that holds hydraulic fluid under pressure and a control valve that regulates the flow of fluid into and out of the accumulator.
2. Storage Device: The main component of the accumulator is the storage device, which is usually a cylinder containing a piston or diaphragm. This device separates the hydraulic fluid and a compressible gas (typically nitrogen) within the cylinder. As hydraulic fluid enters the accumulator, it compresses the gas, storing potential energy in the form of pressurized fluid.
3. Control Valve: The control valve allows for controlled filling and discharge of fluid from the accumulator. It regulates the flow rate and pressure levels, ensuring proper operation of the hydraulic system.
4. Function: Hydraulic accumulators are used to:
   • Store energy to supplement pump flow and pressure during peak demand periods.
   • Dampen pressure surges and pulsations in hydraulic systems.
   • Provide emergency power in case of pump failure or power loss.
5. Other Components Mentioned:
   • Cylinder and Plunger: While these components can be part of certain hydraulic systems or actuators, they do not define a hydraulic accumulator.
   • Two Pistons and Two Cylinders: This configuration is not typical for a hydraulic accumulator, which generally involves a single storage device.
   • Storage Tank and a Ram Pump: These are components of other hydraulic systems but do not describe a hydraulic accumulator.