PS50 Hydraulic Operated Disc Brakes for JC50 DRAWWORK JC50 Disc Brake Actuator consists of brake disc, service calipers (normally open calipers), safety calipers (normally closed calipers) and caliper bracket. It provides service braking and safety parking braking functions. 1. Brake Disc Installation location: Both sides of the JC50 drum shaft. The unilateral wear limit is 5 mm. Structure: Available in water-cooled and air-cooled types, serving as the reference surface for