問題一覧
1
under normal conditions, in order to engage the parking brakes the driver must firts
let the air out of the air brake system
2
excessive use of the service brakes results in over-heating, which can lead to
expansion of the brake drums
3
the brake system that applies and release the brakes when the driver uses the brake pedal is the
service brake system
4
the use of air brakes on a long/or steep downgrade under normal conditions is only a supplement to
the braking effect of the engine
5
during normal driving, spring brakes are usually held back by
air pressure
6
a supply pressure gauge tells you how much air is in the
air tanks
7
the brake pedal in an air brake system
controls the air pressure applied to put on the brakes
8
modern air brake systems combine three different system. They are the service, parking and the
emergency brakes
9
the braking power of the spring brakes
depend on the service brakes being in adjustment
10
the parking or emergency brake on a heavy vehicle can only be held in position by something that cannot leak away, like
spring pressure
11
the driver must be able to see a warning before air pressure in the service air tanks falls below
60 psi
12
under ideal conditions, a truck with air brakes going 55 miles per hour would requiere a stopping distance of
more than 300 feet
13
a slack adjuster probably needs to be adjusted if it moves more than about
1 inch when you pull hard on it
14
emergency stab braking is when you
brake as hard as you can, release the brakes when lock, put on the brakes again when the wheels start rolling
15
with air brake vehicle, the parking brakes should be used
whenever you leave the vehicle unattended
16
if you must make an emergency stop, brake so you
can steer and your vehicle stays in a straight line
17
the air compressor should stop pumping at about
125 psi
18
the air compressor governor controls
when air is pumped into the air tanks
19
if you make an emergency stop, brake so you
can steer and your vehicle stays in a straight line
20
if your truck or bus has dual parking control valves, you can use pressure from a separate tank to
release the spring emergency/parking brakes to move a short distance
21
your vehicle has a dual air brake system. If a low pressure warning comes on for the secondary system, you should
bring the vehicle to a safe stop and continue only when the system is fixed
22
for air brake systems in good condition, the air compressor should start pumping at about
100 psi
23
emergency controlled braking is when you
brake as hard as you can, release the brakes when the wheels lock and put the brakes back on again when the wheels start rolling
24
the most important thing to do when a low air pressure warning comes on is
stop and safely park as soon as possible
25
the spring brakes used on tractors and straight trucks will bring your truck to a stop when the air pressure drops below
20 psi
26
to check the free play of manual slack adjuster on S-Cam brakes, you should park on
level ground, chock the wheels, and turn off the parking brakes
27
excessive heat caused by using your brakes too often can cause the
brakes to fade or fail
28
if your truck has a dual air system and one of the systems is low on pressure
either the front or rear brakes will not be fully operational
29
air braking takes more time than hydraulic braking because
air takes more time to flow through the lines than hydraulic fluid
30
if you are driving down a steep downgrade and you have reached your “safe” speed of 40 mph, you would apply the service brakes until your speed drops to
35 mph
31
your truck or bus has a dual air brake system. if low air pressure warning comes on for only one system, what should you do
stop right away and safely park. continue only after the system is fixed
32
in air brake vehicles, the parking brakes should be used
any time the vehicle is parked
33
how should you check that the spring brakes come on when air pressure in the system drops below certain level
Park on level ground, chock the wheels, release the parking brake when you have enough air pressure, shut the engine off and repeatedly press release the brake pedal
34
the application pressure gauge shows how much air pressure you
are applying to the brakes
35
the S-Cam
forces the brake shoes against the inside of the brake drum
36
if air pressure does not build up to normal whitin the correct amount of time, then
your air pressure may drop too low during driving, requiring an emergency stop
37
the safety valve is set to automatically reduce pressure at
150 psi
38
an air brake system is fully charged at
125 psi
39
when is it ok to leave your truck unattended without applying the parking brake or choking the wheels
never