Modulator Unit

Modulator unit consists of inlet solenoid valve, outlet solenoid valve, reservoir pump, pump motor and damping chamber. Modulator unit hydraulic circuit is an independent 4 channel-type, with one channel for each wheel.

Modulator unit reduces caliper fluid pressure directly. It is a circulating-type modulator. It circulates brake fluid through caliper, reservoir and master cylinder.

Modulator unit operates in 4 modes:

• Pressure reduction mode: Inlet valve closed and outlet valve open. Caliper fluid flows through outlet valve to reservoir.
• Pressure retaining mode: Inlet valve closed and outlet valve closed. Caliper fluid is retained by inlet valve and outlet valve.
• Pressure intensifying mode: Inlet valve open and outlet valve closed. Master cylinder fluid is pumped out to caliper.
• Motor operation mode: When starting pressure reduction mode, pump motor is on. When stopping ABS operation, pump motor is off. Reservoir fluid is pumped out by pump, through damping chamber, to master cylinder.