18.2. Pumping of brakes
Pumping of brakes is necessary when replacing brake fluid, and also for removal of the air which got to a hydraulic actuator at repair or replacement of separate knots of the brake system.
We perform work together with the assistant to news agency a viewing ditch or the elevator. Air is deleted at first from one contour of system (forward right — back left cylinders), then from another.
We remove protective caps from unions of pumping of all working brake cylinders.
If the union does not manage to be unscrewed, before its pumping it is possible to shift previously a six-sided cap key "on 8" or a high head of the same dimension.
We put on a transparent hose the union of the brake cylinder of the left back wheel and we lower its free end in a vessel with brake fluid.
The assistant presses a brake pedal three-four times with an interval one-two seconds and holds a pedal of pressed.
Key "on 8" we unscrew the pumping union on 1/2-3/4 turns.
By pressing a pedal a part of brake fluid and air are forced out in a vessel, and the pedal falls to a floor. Vials of air are well visible in a transparent hose or in a vessel with liquid. We wrap the union of pumping and we continue pumping until an exit of vials of air does not stop.
During removal of air from system we watch liquid level in a tank of the main brake cylinder, if necessary adding it.
We pump over other cylinder of the same contour — forward right.
Similarly we pump over the second contour of the brake system.
In process of removal of air from system the brake pedal has to become "rigid", i.e. when pressing to pass no more than a half of distance to a floor.
After full removal of air from the brake system at inclusion of ignition the control alarm lamp of critical condition of the brake system usually lights up, indicating that pistons of the signaling device are not on average situation. To displace pistons and by that to extinguish a control lamp, it is necessary to create pressure in the brake system (the assistant has to smoothly, but strongly press a brake pedal, watching a control lamp at the included ignition). At this time slightly we weaken an inhaling of one of unions of brake tubes on the main cylinder, having depressurized a contour of the brake system. If the lamp went out, immediately we wrap the union. If the lamp did not go out, and the brake pedal slowly fell to a floor, then, holding a pedal of pressed, we wrap the union of this contour and we repeat operation with another.
It is possible to adjust the signaling device and in a different way. We unscrew the switch of the control alarm lamp of critical condition of the brake system and we insert a core into the opened opening (see. "Removal of the signaling device"). While the assistant presses a brake pedal, we will depressurize one of contours of the brake system and we watch the core course, resting it against a ball. If the ball entered a piston pro-point, follows, holding a pedal of pressed, to wrap the weakened union. If the ball did not enter a pro-point, we repeat operation with the second contour.