Pressure Dropping Phase
If wheels still tend to lock in spite of constant hydraulic pressure because of road surface changing from dry to slippery, pressure in wheel brake cylinder must be reduced. Current higher than about 5 amps on the solenoid valve causes a greater piston stroke, which opens the outlet.
Hydraulic fluid flows to pump reservoir and return delivery pump. Return delivery pump returns brake fluid to master cylinder against existing pressure. A damper in each brake circuit stops delivery noise. The pump always runs during regulation.