"Gazelle" Gas-2705>> Brake system>> Maintenance service and repair of brake systems>> Filling with a liquid of brake system. Removal of air from brake system (prorolling)
The brake system is pumped over at replacement of a brake liquid, at hit in air hydrodrive, at carrying out of the repair work connected with depressurization of system.
The hydraulic drive has two independent contours, therefore each contour is pumped over separately. Prorolling should be begun with the brake mechanism, the most remote from the main brake cylinder, that is from the right. Prorolling is carried out by two executors in a following order:

Fig. 8.3. The main brake cylinder: 1 — the case; 2 — a tube; 3 — the connecting plug; 4 — a tank; 5 — a protective cap; 6 — the gauge of a signalling device of emergency falling of level of a brake liquid; 7 — a persistent ring; 8 — an external cuff; 9 — the directing plug; 10, 17 — pistons; 11 — a lock ring; 12 — a sealing ring; 13 — a piston washer; 14, 16 — cuffs; 15, 18 persistent washers; 19 — a spring: 20 — a stopper; And, In — compensatory apertures; With — перепускные apertures

- To turn away the gauge 6 (fig. 8.3 see) and to fill in in a tank 4 brake liquid to a label the MOVE;
- To clear of a dirt valves of prorolling of forward and back brake mechanisms, to remove from prorolling valves rubber protective caps;
- To put on a head of the valve of the right back wheel cylinder a hose plum of a brake liquid. The free end of a hose to lower in the brake liquid poured in a pure transparent vessel;
- To turn away the prorolling valve on 1/2 — 3/4 turns, to press a brake pedal. In position of completely pressed pedal, the assistant should wrap the prorolling valve. To repeat this operation until will stop allocation of vials of air;
- After the termination of prorolling the assistant should wrap densely the valve while the brake pedal is kept in the pressed position. To remove a hose and to put on a protective cap;
- In the same sequence to pump over back left and forward brake mechanisms.
At removal of air from a hydrodrive of brakes it is necessary to add in due time a brake liquid in a tank, without supposing "a dry" bottom.
After prorolling to add a brake liquid in a tank to a label the MOVE. If prorolling is executed insufficiently carefully by pressing a pedal of a brake in the end of its course some elasticity, big or smaller depending on quantity of air which has remained in system will be felt. The pedal course thus increases a little. In this case it is necessary to repeat prorolling.
Replacement of a brake liquid
Replacement of a brake liquid in system is necessary, as it at operation absorbs a moisture from atmosphere, than worsens the temperature properties and causes corrosion of cylinders and pistons. Liquid replacement is made at seasonal service of the car (once a year).
For replacement of a brake liquid it is necessary:
- To turn away a cover of a tank from the main brake cylinder, to remove protective caps from prorolling valves;
- To put on heads of valves the rubber hoses which free ends to lower in transparent vessels, and then to turn away all valves on 1/2 — 3/4 turns;
- To merge fulfilled liquid from system, vigorously pressing a pedal of a brake and smoothly releasing it. In process of the termination of the expiration of the fulfilled liquid to wrap prorolling valves;
- To merge from vessels fulfilled liquid and to put them into place under rubber hoses; to fill in a fresh brake liquid in a tank of the main brake cylinder and to turn away all valves of prorolling. Vigorously pressing and smoothly releasing a brake pedal, and also in due time filling up a tank with a brake liquid, to fill system with a fresh brake liquid; in process of occurrence in vessels of a pure brake liquid to wrap prorolling valves;
- To pump over system by the technique described above.