Booster; Vacuum Booster Assembly; When Foot Brake Pedal Is Not Depressed - Suzuki Samurai 1986 Service Manual

[Booster OPERATION]
1. Booster No. 1 body
2. Booster No. 2 body
3. Valve operating rod
4. Air cleaner element
5. Air cleaner separator
6. Air valve spring retainer
7. Air valve return spring
8. Control valve spring retainer
9. Control valve spring
10. Booster control valve
11. Booster air valve
12.
Booster piston
13.
Valve stopper key
14. Booster diaphragm
15. Reaction disc
16. Booster piston return spring
17. Booster piston rod
18. Booster rod adjust screw
19. Vacuum check valve
Fig. 19-13-1 Vacuum Booster Assembly
When the brake pedal is depressed, the force is transmitted to the piston of the master cylinder through
the valve operating rod, booster air valve, reaction disc and piston rod. At the same time, the force of the
booster piston developed due to the pressure difference between the two chambers "A" and "B" in the
above figure is added to it.
The end of the booster control valve has a double function of a vacuum valve and air valve. That is, as
shown in the figure, the booster control valve closes between the "A" and "B" chambers as its outer end
"C" contacts the booster piston seat and opens as "C" leaves the booster piston seat (vacuum valve
function). Also it closes between the "B" chamber and outside air as its inner end "D" contacts the air
valve seat and opens as "D" leaves the air valve seat (air valve function).

When foot brake pedal is not depressed

The valve operating rod is pushed to the right by the spring force as shown. The air valve is also enough to
the right to contact the valve stopper key as shown. In this state, the vacuum valve (control valve "C") is
open and the air valve (control valve "D") is closed. Thus the chambers "A" and "B" conduct and share
the same negative pressure (because of no pressure difference) which allows the return spring to push the
booster piston to the right.
"B"
I
Fig. 19-13-2 Vacuum Booster Assembly
19-12
Vacuum valve "C"
Air valve "D"
Control valve
1. Booster control valve
2. Booster air valve
3. Booster piston
1
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