Power Unit: Notes
The power unit consists of a motor and a plunger-type pump. This unit transmits the revolution of motor to plunger by way of an eccentric bearing and supplies high-pressure brake fluid to the accumulator by effect of reciprocating movement of plunger. When pressure in accumulator drops below prescribed pressure level, pressure switch gives an OFF signal. ABS control unit turns motor relay ON to start operation of pump, upon reception of this signal and a signal from wheel sensor that vehicle is running at a speed greater than 10 km/h. When pressure in accumulator attains prescribed pressure, ABS control unit turns motor relay OFF approximately three seconds after unit receives an ON signal from pressure switch. By this, high-pressure in accumulator is maintained. ABS control unit turns pump off and lights system indicator light if accumulator pressure does not reach prescribed level after pump has run continuously for 120 seconds. See Fig 4 .