Hydraulic Control Unit (HCU) (Discovery 3)

HCU Block (hydraulic control unit) is a 4-channel unit that regulates the supply of hydraulic pressure to the brake mechanisms under the control of the ABS module (anti-lock braking system).

HCU Block (hydraulic control unit) is secured in the engine compartment by three mounting bushings to a bracket in the driver's side storage chamber. Hydraulic lines connect the HCU (hydraulic control unit) with master cylinder and brake assemblies. For more information, refer to Hydraulic Brake Actuation (206-06).

The main and auxiliary outlet ports of the master cylinder are connected to the main and auxiliary circuits of the HCU. (hydraulic control unit). Main circuit of the HCU block

(hydraulic control unit) has separate outlets for the front brakes.

HCU auxiliary circuit (hydraulic control unit) has separate outlets for the rear brakes. Each circuit of the HCU (hydraulic control unit) contains the following units and parts that allow you to adjust the hydraulic pressure applied to the brakes:

Information obtained from the website [lrman.ru]

• Normally open electromagnetic control valve providing active braking.
• A normally closed electromagnetic filler valve that connects the brake fluid reservoir to the return pump during active braking.
• A return pump that creates hydraulic pressure for active braking and ensures the return of brake fluid to the reservoir.
• Normally open electromagnetic inlet valves and normally closed electromagnetic outlet valves that regulate the pressure in individual brake mechanisms.
• Receiver and relief valve that allows you to quickly release pressure in the brake mechanisms.
• Filters that protect components and parts from contamination.

The main circuit also includes a pressure sensor that transmits to the ABS module. (anti-lock braking system) hydraulic pressure signal.



HCU Contact Pins (hydraulic control unit) fit into the ABS module contact sockets (anti-lock braking system), providing electrical connections between the return pump motor and the pressure sensor with the ABS module (anti-lock braking system).

The solenoids that control the valves are installed in the ABS module. (anti-lock braking system).

HCU spare units (hydraulic control unit) already filled with liquid. After installing the unit on the car, it is necessary to use T4 to turn on the solenoid valves and the return pump to properly remove air from the HCU (hydraulic control unit) and brake circuits.