What stores energy to power braking when hydraulic pressure drops?

• A. Oil reservoir
• B. Accumulator
• C. Brake pad friction material
• D. Hydraulic pump

Answer: (B)

Energy storage in a hydraulic braking system is provided by an accumulator. It stores hydraulic energy in a pressurized fluid separated from a compressed gas chamber. When hydraulic pressure drops, the gas expands and pushes the fluid out to the brake lines, delivering additional flow and maintaining brake force for a short time until the pump can rebuild pressure. This makes the accumulator ideal for powering braking during a drop in hydraulic pressure, ensuring continued braking and pedal feel.

Other components don’t store energy for this purpose: the oil reservoir simply holds fluid, the brake pad material converts energy to heat during friction (not stored for later use), and the hydraulic pump is the active source of pressure rather than a storage device.