Doosan DX60R Shop Manual page 527

Brake Part
The swing brake is spring applied and hydraulically released.
Friction plate (15) are splined to and rotate with cylinder block.
separation plates (15) are splined to the motor casing (1).
When the swing controller blocks pilot pressure at port (SH), the
brake springs (17) force on brake piston (16) squeeze the
separation and friction plates together to prevent the upper
structure from swinging.
Figure 5 Brake Working Description
Swing Motor SP001630
Page 13