7.1.7. Removal of air from a hydraulic actuator
The air which got to a hydraulic actuator of the working brake system during the replacing of pipelines, hoses, sealing rings or leaks of a hydraulic actuator causes increase in the working course of a pedal of a brake, its "failures" and "softness", and also reduces efficiency of braking.
Before removal of air from a hydraulic actuator be convinced of tightness of all knots of the working brake system and their connections, check and if necessary fill a tank to normal level with Neva or Tom liquid. Then carefully clear of dirt and raise dust unions for removal of air and remove from them protective caps.
Air is deleted at first from one contour, then from another, beginning every time with the contour wheel, most remote from the main cylinder.
You carry out pumping of a hydraulic actuator in the following order.
Fig. 7-6. Removal of air from pipelines of system of the hydraulic drive of brakes of the left forward wheel: 1 — a hose for pumping; 2 — a vessel for brake fluid
Put on an union head a rubber hose of 1 (fig. 7-6) for pumping, and lower other its end in the transparent vessel 2 which is partially filled with liquid.
Having sharply pressed a pedal of a brake of 3-5 times, with intervals between pressing 2–3 with, unscrew on 1/2–3/4 turns the union at the pressed pedal. Continuing to press a pedal, force out the liquid which is in system together with air through a hose in a vessel. After the pedal will reach extreme forward situation and liquid does not follow through a hose, wrap the union of production of air to the full. These operations should be repeated until an exit of bubbles from a hose stops.
Holding a pedal in the pressed situation, wrap the union of production of air to the full and remove a hose. Wipe dry the union and put on a protective cap.
Repeat operations for other wheels, at first on the second wheel of the same contour, and then it is consecutive on both wheels of the second contour.
During removal of air support the normal level of liquid in a tank of a hydraulic actuator of brakes.
At absence the pedal of a brake should not pass more than 1/2-2/3 courses in an air hydraulic actuator.
To exclude influence of the regulator of pressure upon pumping of the drive of brakes, you carry out removal of air at the loaded back wheels (posting of a back part of the car is not allowed).
If brake fluid was completely merged from system, then before removal of air from system:
— unscrew on 1,5–2 turns unions of removal of air on cylinders of all wheels;
— sharply pressing a pedal of a brake and slowly releasing it, wrap unions in process of an effluence of liquid from them. Then carry out pumping of the drive as it is stated above.
Even if during long removal air continues to come out a hose in the form of bubbles, it means gets into system through damages to pipelines because of insufficient tightness of connection or owing to malfunction of the main thing or wheel cylinders.
If removal of air is carried out on the car which brake system worked long term, then replace the liquid which is in system new.
The liquid suitable for further use, it is necessary to filter carefully and then to allow to be defended in hermetically closed vessel.