Chapter 10: GENERAL INFORMATION FOR
CLASS D "CHAUFFEUR'S" LICENSE- Qs & As
Parts of an air brake system: Air Tank Drains (2 types) Correct Ans-1. Manual - operated by
turning a quarter turn or by pulling a cable. You must drain the tanks yourself at the end of each
day of driving.
2. Automatic - the water and oil is automatically expelled. They may be equipped for manual
draining as well.
Parts of an air brake system: Safey Valve Correct Ans-Protects the tank and the rest of the
system from too much pressure. The valve is usually set to open at 150 psi. If the safety valve
releases air, something is wrong.
Parts of an air brake system: Brake Pedal Correct Ans-You put on the brakes by pushing down
the brake pedal. Pushing the pedal down harder applies more air pressure. Letting up on the
brake pedal reduces the air pressure and
releases the brakes. Pressing and releasing the pedal unnecessarily can let air out faster than
the compressor can replace it. If the pressure gets too low the brakes won't work.
Parts of an air brake system: Supply Pressure Gauges Correct Ans-All vehicles equipped with
air brakes have a pressure gauge connected to the air tank. These gauges tell you how much
pressure is in the air tanks.
Parts of an air brake system: Application Pressure Gauge Correct Ans-This gauge shows how
much air pressure you are applying to the brakes. (This gauge is not on all vehicles.)
, Parts of an air brake system: Low Air Pressure Warning Correct Ans-A low air pressure
warning signal is required on vehicles with air brakes. A warning signal you can see must come
on before the air pressure in the tanks falls below 60 psi. (Or one half the compressor governor
cutout pressure on older vehicles). The warning is usually a visable red light. A buzzer may also
come on.
Parts of an air brake system: Spring Brakes: Correct Ans-All trucks must be equipped with
emergency brakes and parking brakes. They must be held on by mechanical force. Spring brakes
are usually used to meet these needs. When
driving, powerful springs are held back by air pressure. If the air pressure is removed, the
springs put on the brakes.
Parts of an air brake system: Parking Brake Controls: Correct Ans-In newer vehicles with air
brakes, you engage the parking brakes using a diamond shaped, yellow, push-pull control knob.
You pull the knob out to put the parking brakes
(spring brakes) on, and push it in to release them. On older vehicles, the parking brakes may be
controlled by a lever. Use the parking brakes whenever you park. NEVER PUSH THE BRAKE
PEDAL DOWN WHEN THE SPRING BRAKES ARE ON. If you do, the brakes could be damaged.
INSPECTING THE AIR BRAKE SYSTEM The following three-part air brake check must be
performed: Correct Ans-Step 1: With the engine running, build the air pressure to governed
cut-out (100-125 psi). Shut off the engine, chock your wheels, if necessary, release the tractor
protection
CLASS D "CHAUFFEUR'S" LICENSE- Qs & As
Parts of an air brake system: Air Tank Drains (2 types) Correct Ans-1. Manual - operated by
turning a quarter turn or by pulling a cable. You must drain the tanks yourself at the end of each
day of driving.
2. Automatic - the water and oil is automatically expelled. They may be equipped for manual
draining as well.
Parts of an air brake system: Safey Valve Correct Ans-Protects the tank and the rest of the
system from too much pressure. The valve is usually set to open at 150 psi. If the safety valve
releases air, something is wrong.
Parts of an air brake system: Brake Pedal Correct Ans-You put on the brakes by pushing down
the brake pedal. Pushing the pedal down harder applies more air pressure. Letting up on the
brake pedal reduces the air pressure and
releases the brakes. Pressing and releasing the pedal unnecessarily can let air out faster than
the compressor can replace it. If the pressure gets too low the brakes won't work.
Parts of an air brake system: Supply Pressure Gauges Correct Ans-All vehicles equipped with
air brakes have a pressure gauge connected to the air tank. These gauges tell you how much
pressure is in the air tanks.
Parts of an air brake system: Application Pressure Gauge Correct Ans-This gauge shows how
much air pressure you are applying to the brakes. (This gauge is not on all vehicles.)
, Parts of an air brake system: Low Air Pressure Warning Correct Ans-A low air pressure
warning signal is required on vehicles with air brakes. A warning signal you can see must come
on before the air pressure in the tanks falls below 60 psi. (Or one half the compressor governor
cutout pressure on older vehicles). The warning is usually a visable red light. A buzzer may also
come on.
Parts of an air brake system: Spring Brakes: Correct Ans-All trucks must be equipped with
emergency brakes and parking brakes. They must be held on by mechanical force. Spring brakes
are usually used to meet these needs. When
driving, powerful springs are held back by air pressure. If the air pressure is removed, the
springs put on the brakes.
Parts of an air brake system: Parking Brake Controls: Correct Ans-In newer vehicles with air
brakes, you engage the parking brakes using a diamond shaped, yellow, push-pull control knob.
You pull the knob out to put the parking brakes
(spring brakes) on, and push it in to release them. On older vehicles, the parking brakes may be
controlled by a lever. Use the parking brakes whenever you park. NEVER PUSH THE BRAKE
PEDAL DOWN WHEN THE SPRING BRAKES ARE ON. If you do, the brakes could be damaged.
INSPECTING THE AIR BRAKE SYSTEM The following three-part air brake check must be
performed: Correct Ans-Step 1: With the engine running, build the air pressure to governed
cut-out (100-125 psi). Shut off the engine, chock your wheels, if necessary, release the tractor
protection
