AIR BRAKES : 2 AIR BRAKES AIR BRAKES USE COMPRESSED AIR TO MAKE
THEM WORK. YOU CAN APPLY ALL THE
BRAKING FORCE YOU NEED TO EACH WHEEL
OF A VEHICLE, EVEN TRACTORS PULLING
TRAILERS. IF MAINTAINED AND USED PROPERLY
THEY WILL SAFELY STOP LARGE VEHICLES.
Slide 3: DUAL AIR BRAKING SYSTEM:
As its name suggests, the dual system is two
systems or circuits in one. There are different
ways of separating the two parts of the system.
On a two–axle vehicle, one circuit operates the rear
axle and the other circuit operates the front axle.
If one circuit has a failure, the other circuit is
isolated and will continue to operate.
Slide 4: BASIC TYPE:
When a brake
application is made, air is drawn from the primary
reservoir through the foot valve and is passed on to
the rear brake chambers. At the same time, air is
also drawn from the secondary reservoir, passes
through the foot valve and is passed on to the front
brake chambers. If there is air loss in either circuit,
the other will continue to operate independently.
Unless air is lost in both circuits, the vehicle will
continue to have braking ability.
Slide 5: DUAL BRKING SYSTEM WITH SPRING PARKING TECHNOLOGY:
When spring brakes are added to a dual air brake
system, the same type of dash control valve discussed
previously is used. Blended air is used to supply
the spring parking brake control valve (27). Blended
air is air taken from the primary and secondary circuits
through a two–way check valve (26). With this
piping arrangement the vehicle can have a failure
in either circuit without the spring brakes applying
automatically. If air is lost in both circuits, the
spring brakes will apply.
Slide 6: SPRING
PARKING SYSTEM WITH MODULATOR VALVE :
Spring parking brakes in this system serve two
purposes: first, as a parking brake, and second
as an emergency braking system. If a failure occurs
in the primary circuit (green), and a brake application
is made, control air from the foot valve is directed to
a spring brake modulator valve (23). As there is no
supply air to maintain balance in the modulator valve,
because of the primary circuit failure, the modulator
valve then exhausts air pressure from the spring
parking brake circuit.
Slide 7: Combination Tractor and Trailer
with Spring Parking Brakes
The trailer system is supplied by blended tractor air
taken from the primary and secondary circuits through
a two–way check valve as previously described.