Question

in a hydraulic accumulator brake system, parking brakes are: 1) hydraulically applied and hydraulically released 2) spring applied and spring released 3) hydraulically applied and spring released 4) spring applied and hydraulically released

Explanation:

In a hydraulic accumulator brake system, parking brakes are designed to be applied by springs (to ensure they engage in case of hydraulic failure) and released hydraulically (when the system has pressure to disengage them). Option 1 is incorrect as parking brakes don't rely solely on hydraulics for both. Option 2 is wrong since they aren't spring - released. Option 3 has the application and release mechanisms reversed. Option 4 correctly describes the parking brake operation in this system.

Answer:

1. Spring applied and hydraulically released