VDOT Flashcards
How much play in a steering wheel is allowed
No more than 10° approximately 2 inches in a 20 inch steering wheel
For airbrakes air pressure should build from 50 psi to 90 psi how fast
3 minutes
Oil pressure at idle should read what
5-20 psi
Oil pressure while operating should read what
35-75 psi
drivers should look at least how many seconds ahead
12-15 seconds
If stopped on or near one way or divided highways you should place 2 warning devices how far from the vehicle
10’
100’
If you stop on a two-lane Road caring traffic in both directions or Undivided-highways You should place warning devices where
Within 10 feet of the front or rear corners of the vehicle and 100 feet behind in ahead of the vehicle
total Stopping distance is the sum of what?
perception distance
reaction distance
braking distance
Define perception distance
Distance vehicle travels under ideal conditions from Time eyes see a hazard until brain recognizes it
Define reaction distance
Distance travel under ideal conditions before physically touching breaks in response to hazard seen
Define braking distance
Distance vehicle travels and ideal conditions while breaking
If you double your speed from 20 to 40 miles per an hour the impact power increases how many times greater
4x
True or false empty trucks require greater stopping distances
True
less weight means less traction for the tires and brakes
When driving on a slippery surfaces reduce speed by how much of a fraction
1/3
When driving on icy surfaces produce speeds by how much of a fraction
1/2
In regards to managing space, you need at least one second for each how many feet at speeds below 40 miles an hour
10’
When using low beams, you can see ahead about how many feet
250
When using high beams you can see ahead about how many feet
350-500’
True or false air pressure increases when temperature increases
true
At train crossings vehicles must stop no closer than how many feet
15’
what are four Causes for Skidding
Over breaking
over steering
over acceleration
driving too fast
When does the low air pressure warning signal come on
when air pressure in tank falls below 60 PSI
When do emergency breaks come fully on
When air pressure drops to arrange of 20 to 40 psi
Before driving a vehicle with dual air systems front and rear allow time for air compressor to build up a minimum of how much psi
100
At what psi should air compressor kick on
100 psi
At what psi should air compressor kick off
125 psi
To test for air leakage while the engine is off an air system charged release the parking brake a loss rate how many psi in one minute should occur
Less than 3 psi per minute for single vehicles
less than 4 psi per minute for combination vehicles
When the engine is operating at RPM the pressure should bill from 85 to 100 PSI within how many seconds
45
what factors contribute to total stopping distance for airbrake vehicles
Perception distance
reaction distance
brake lag distance
braking distance
While inspecting engine compartment belts how much play should be at the center of the belt
1/2” to 3/4”
what are 3 types of vehicle inspections
vehicle inspection
during trip
after trip
when do you do a after trip inspection
At the end of the trip day or tour of duty
How much of a leaf spring must be missing before vehicle will be placed out of service
1/4
Air pressure governor should cut out around what range
120-140 psi
Oil pressure at idle should read what range
5-20 psi
Oil pressure while operating should read between what ranges
35-75
How to test parking brakes
Set parking brake
place vehicle in low gear
gently pull forward against brake
How to test service brakes
Accelerate to 5 miles an hour
press break
notice pulling or unusual feel
Safe operation of a vehicle requires skills and what four categories
Accelerating
steering
stopping
packing
When driving an automatic transmission downhill is important to use which range of gear to prevent the transmission from shifting up
low range
define a hazard
any road conditions or users that is a possible danger
with only —- hours of sleep, triples risk of an accident
6 hours
Working more than 60 hours a week increases your risk of an accident by how much of a percent
40%
What is an indication that you have lost your anti-lock braking system
Lamp light stays on dashboard after the bulb check
Define over breaking
Breaking too hard and locking up the wheels causing a skid
Define oversteering
Turning the wheels more sharply in the vehicle concern resulting in a skid
Define over acceleration
Supplying too much power to the drive wheels causing them to spend
What is the most common type of skid
Driving too fast rear wheels lose traction
What are the steps and correcting a drive wheel braking skid
Stop breaking countersteer by turning the vehicle back on course
What are the steps when in a front wheel skid
Let the vehicle slow down
What is the purpose of the alcohol evaporator in the air brake system
alcohol may be added to the air system to reduce risk of ice buildup in the valves
Define dual air brake system
Two separate air brake systems using a single set of brake controls each system has its own air tank hoses and lines one system typically operates rear axle the other the front
Do you still have to check automatic slack adjusters for movement of more than 1 inch from where the pushrod attaches
Yes if there is more they need to be adjusted by certified mechanic
Brake drums must not have a crack longer than ??? of the width of the friction area
1/2
When testing air leak first turn off engine release the brake in time pressure drop for one minute how much 2 psi is permitted for single vehicles and 3 for a combination vehicles
then apply foot to break and hold for one minute see if air pressure drops more than three psi for single and four psi for combination
then continuously pump service brake until low pressure warning signal turns on around 60 psi
continue fanning off the air pressure by stepping on an offbreak pedal to reduce tank pressure parking brake valve should pop out at 20 to 45 psi
start engine pressure should build from 85 to 100 psi within 45 seconds on dual air systems
to test parking break stop the vehicle put the break on and gently pull against it and a low gear to see if parking break holds
To test service brakes wait for the normal air pressure release the parking brake and I move the vehicle forward slowly at 5 miles/ an hour apply service brakes and know any pulling or unusual feel delayed stopping action
