In the brake system, which component keeps the compensator port open when the pedal is not depressed?

• A. Piston
• B. Gasket
• C. Seal
• D. Sleeve

Answer: (D)

The idea here is that the compensator port must remain open in the resting state so hydraulic fluid can flow and the system returns to neutral smoothly. The sleeve is a stationary cylindrical guide around the valve stem that defines the bore and keeps the compensator port unobstructed when the pedal isn’t pressed. By maintaining the proper clearance, the sleeve prevents the piston lip from sealing off the port in idle, allowing that small, required flow to keep the system ready for rapid response when the brakes are applied. The piston moves to apply pressure and can close the port during actuation, while seals and gaskets are there to prevent leakage and to seal surfaces, not to keep the port open.