Escort L4-110 1.8L DOHC (1994)
ABS Hydraulic Unit: Description and Operation
The hydraulic anti-lock actuator assembly contains solenoid valves, flow control valves, a pump motor and buffer chambers. The solenoid valves open
and close by signals sent by the anti-lock brake control module. The flow control valves move according to the solenoid valve condition and control the
hydraulic pressure in the brake calipers (pressure reduction or pressure increase). The hydraulic anti-lock actuator assembly has four solenoid valves
which operate the three-channel system.
During normal braking, fluid from the brake master cylinder enters the two inlet ports located on top of the hydraulic anti-lock actuator assembly. The
fluid then passes through the normally open solenoid valves to each respective wheel location. If the anti-lock brake control module senses a wheel is
about to lock, the anti-lock brake control module sends an electronic signal to close the flow control valve of the affected circuit. This action regulates
the brake fluid entering the affected brake circuit, preventing wheel lockup. If the anti-lock brake control module senses the affected wheel is continuing
to decelerate, the anti-lock brake control module sends a signal to open the normally closed flow control valve in the affected circuit. This action reduces
any pressure trapped between the flow control valve and the affected brake actuator. The brake fluid is returned to the brake master cylinder reservoir.
