Abstract: The hydraulic actuation system (10) utilizes efficiently stored hydraulic pressure to effect a higher final pressure in the system (10) for a parking brake application. The system includes a pump (12) which communicates separately with accumulators or pressure storage mechanisms (20, 30) isolated from one another. A first accumulator (20) communicates with a first three-position apply and release valve mechanism (40) that can communicate via an apply hydraulic line (26) with a second two-position apply valve mechanism (50). The second accumulator (30) communicates with the second apply valve mechanism (50). The second apply valve mechanism (50) communicates the apply hydraulic line (26) with apply lines (55, 63, 73) and at least one brake (60, 70) that is hydraulically actuated for a parking brake application. The brake (60, 70) includes a release hydraulic line (62, 72, 49) which communicates with the first apply and release valve mechanism (40).