HEXA

Anti-lock Braking System(ABS)

ii. HYDRAULIC CONTROL UNIT (HCU) / HYDRAULIC MODULATOR :

: Front right

: Rear Left

: Rear Right

: Front Left

MC1

and

MC2

: Primary and Secondary brake circuits

RREV

and

RRAV

: Inlet and Outlet solenoid valves of rear right wheel

LFEV

and

LFAV

: Inlet and Outlet solenoid valves of front left wheel

LREV

and

LRAV

: Inlet and Outlet solenoid valves of rear left wheel

and

: Accumulators of the circuits MC1 and MC2 respectively

RP1

and

RP2

: Recirculating pump of the circuits MC1 and MC2 respectively

Motor for driving Recirculating pumps

It consists of a Return Pumps, Solenoid Valves,

Damping Chamber, Accumulator, Non-Return

Valve and Motor. It forms the link between the

TMC and the foundation brakes. It implements the

commands issued by the ECU by using solenoid

valves to control the pressure at the foundation

brakes.

There are four pairs (4-channel system) of Inlet

and Outlet valves located in the modulator.

Solenoid valves are responsible for modulating

the pressure in the wheel brake during active ABS

control.

The Return Pump element is installed in the

center of the modulator and is driven by an

electric Motor. The pump transfers the brake fluid

emerging from the wheel brakes through the

accumulator on its way back to the TMC. The

pump and valve actuation can be felt on the foot

pedal as pulsations. In order to prevent damage to

the TMC primary seals from the compensating

port, the design of TMC is changed to central

valve type (CV/CV).