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6.7.1. Pumping of brakes

Fig. 6.15. Fill in fresh brake fluid


Use only the fresh DOT 3 or DOT 4 brake fluid.
Pumping from a hydraulic actuator of the working brake system is necessary for removal of air which considerably reduces efficiency of braking. Air can get to the hydraulic drive owing to depressurization of system at repair, replacement of separate knots or brake fluid. Point the increased course of a pedal of a brake and its "softness" to availability of air in the drive. Before removal of air check tightness of all knots of the drive of brakes and their connections.
In the course of pumping of the brake system the level of brake fluid should not fall below the middle of a tank of a hydraulic actuator of the working brake system.
Carry out pumping of brakes in the following sequence:
1 – back right working cylinder of a brake;
2 – back left working cylinder of a brake;
3 – forward right support of a brake;
4 – forward left support of a brake.
Lift the car.
Disconnect brake tubes from the main brake cylinder.

Fig. 6.16. Smoothly press a brake pedal


Smoothly press a pedal of a brake and hold its (fig. 6.16).

Fig. 6.17. Release a brake pedal


Stop up exhaust outlets of the brake cylinder with fingers and release a pedal of a brake (fig. 6.17).
Repeat operations three – four times.

Fig. 6.18. Pumping of the brake system


Connect a vinyl tube to the union of pumping of the wheel brake cylinder (fig. 6.18).

NOTE
Begin pumping with the wheel brake cylinder which is most removed from the main brake cylinder.

Press a brake pedal several times, then, holding a pedal in the pressed state, weaken a pumping union inhaling.
When brake fluid ceases to come out, tighten the union, then release a brake pedal.
Inhaling moment: 8,3 N · m.
Repeat pumping operations until in the coming-out brake fluid vials of air do not cease to appear.
Repeat the procedure of pumping for each wheel.
Check the level of brake fluid in a tank and add liquid in case of need.