Dual piston swing brake system for cranes

A dual piston hydraulic brake for a rotating crane, having both a service brake and a parking brake, comprising:

• a stationary housing having an interior surface and a top member;
• a brake driver within said stationary housing;
• at least two non-rotational stator disks encircling said brake driver, said stator disks being coaxial with said brake driver, axially movable, and wherein there is an uppermost stator disk and a lowermost stator disk;
• at least one friction disk between said stator disks, said friction disks encircling said brake driver, being coaxial with said brake driver and said stator disks, being in communication with said brake driver, and being axially movable;
• said stator disks and said friction disks constituting a single brake pack;
• a parking brake piston coaxial with said stator disks and proximate to said uppermost stator disk;
• spring means for urging said parking brake piston against said uppermost stator disk, thereby applying braking pressure to said stator disks and friction disks;
• a first hydraulic means acting in opposition to said spring means, whereby said parking brake piston may be moved against said spring means and away from said uppermost stator disk;
• a service brake piston coaxial with said stator disks and proximate to said lowermost stator disk, said service brake piston being independent of said parking brake piston;
• and,
• a second hydraulic means for urging said service brake piston against said lowermost stator disk, thereby applying braking pressure to said stator disks and friction disks, said second hydraulic means being independent of said first hydraulic means.