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2024 ILLINOIS CDL EXAM WITH CORRECT ANSWERS
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2024 ILLINOIS CDL EXAM WITH CORRECT ANSWERS
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2024 ILLINOIS CDL EXAM WITHCORRECT ANSWERS
Three Different Air Braking Systems - CORRECT-ANSWERS-Service Brake:
used during normal driving
-Parking Brake: used during parking brake control
-Emergency Brake: uses parts of the service and parking brake systems to
stop the vehicle in a brake system failure
Air Compressor (air brakes) - CORRECT-ANSWERSpumps air into the air
storage tanks (reservoirs). Connected to the engine through gears or a V-belt
Air Compressor Governor (air brakes) - CORRECT-ANSWERScontrols when the
air compressor will pump air into the air storage tanks. "cut-out" level is
around 125psi. "cut-in" pressure is around 100psi
Air Storage Tanks (air brakes) - CORRECT-ANSWERSused to hold compressed
air, number and size of air tanks varies among vehicles. Tanks will hold
enough air to allow the brakes to be used several times, even if the
compressor stops working.
Air Tank Drains (air brakes) - CORRECT-ANSWERScompressed air usually has
some water and compressor oil in it, which is bad for the air brake system.
Be sure to drain the air tanks completely.
-Manually Operated: by turning a quarter turn or by pulling a cable. Must
drain tanks yourself at end of each day.
-Automatic: water and oil are automatically expelled.
Alcohol Evaporator (air brakes) - CORRECT-ANSWERSsome air brake systems
have an alcohol evaporator to put alcohol into the air system to reduce the
risk of ice in air brake valves
Safety Valve (air brakes) - CORRECT-ANSWERSa safety relief valve is
installed in the first tank the air compressor pumps air into. The safety valve
protects the tank and the rest of the system from too much pressure (usually
set to open at 150psi)
Foundation Brakes (air brakes) - CORRECT-ANSWERSare used at each wheel,
most common type is the S-cam drum brake
, S-cam Brakes (air brakes) - CORRECT-ANSWERSwhen you push the brake
pedal, air is let into each brake chamber. Air pressure pushes the rod out,
moving the slack adjuster, thus twisting the brake camshaft. This turns the
S-cam. The S-cam forces the brake shoe away from one another and presses
them against the inside of the brake drum. When you release the brake
pedal, the S-cam rotates back and a spring pulls the brake shoes away from
the drum.
Wedge Brakes (air brakes) - CORRECT-ANSWERSthe brake chamber push rod
pushes a wedge directly between the ends of two brake shoes. This shoves
them apart and against the inside of the brake drum.
Disc Brakes (air brakes) - CORRECT-ANSWERSair pressure acts on a brake
chamber and slack adjuster, like S-cam brakes. But instead of the S-cam, a
"power screw" is used.
Supply Pressure Gauges (air brakes) - CORRECT-ANSWERStell you how much
pressure is in the air tanks
Application Pressure Gauge (air brakes) - CORRECT-ANSWERSshows how
much air pressure you are applying to the brakes
"Wig Wag" (air brakes) - CORRECT-ANSWERSthis device drops a mechanical
arm into your view when the pressure in the system drops below 60psi
Spring Brakes (air brakes) - CORRECT-ANSWERSusually used to meet the
needs of emergency and parking brakes. When driving, powerful springs are
held back by air pressure. If the air pressure is removed, the springs put on
the brakes. A leak in the air brake system, which causes all the air to be lost,
will also cause the springs to put on the brakes.
Modulating Control Valve (air brakes) - CORRECT-ANSWERSa control handle
on the dash board that may be used to apply the spring brakes gradually
Dual Air Brake (air brakes) - CORRECT-ANSWERShas two separate air brake
systems, which use a single set of air brake controls. Each system has its
own air tanks, hoses, lines, etc. One system typically operates the regular
brakes on the rear axle or axles. The other system operates the regular
brakes on the front axle. Both systems supply air to the trailer. The first
system is called the "primary" system. The other is called the "secondary"
system.
How to check that spring brakes come on automatically - CORRECT-
ANSWERSwith only electrical on, fan off the air pressure by stepping on and
off the brake pedal to reduce tank pressure. When air pressure falls to 20-
45psi this should cause the spring brakes to come on.
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