System Fundamentals Flashcards
The degree of friction is known as
coefficient of friction (COF)
The purpose of any vehicle braking system is
to retard the motion of the vehicle through friction
C O F formula is
eg 60 lbs pulling force/100 lbs of weight = 0.60 or COF 60%
Excessive brake heat may be generated if a vehicle
is overloaded or is speeding
4 factors affecting braking performance
1: material drums, rotors and linings are made of.
2: condition of those materials
3: force applied to those materials
4: temperature of those materials
When maximum temp rating is exceeded on braking materials and coefficient of is severely reduced, it’s called
Brake Fade
Traction is
COF between the vehicles tires and road surface
Power is
the rate at which work is done
If weight is doubled, stopping distance is
2 times as much
the amount of stopping power is _______ times more than acceleration ( 0-60/60-0)
10 times
if speed is doubled, stopping distance is
4 times as much
if speed and weight is doubled, stopping distance is
8 times as much
stopping time is affected by 3 things
reaction time
lag time
braking time
operator reaction time is affected by 4 things
fatigue, alcohol or drugs, physical illness, age
lag time of 0.3 seconds is normal and affected by
air restrictions, brake adjustment, foundation brake equipment, system moisture and contamination, and air leaks
Braking time is time required to stop once the brakes are applied. what are 5 influences
force applied to brake shoes(by the operator), foundation brake condition, vehicle weight and speed, brake lining temperature, traction between tires and road surface
3 air brake advantages are
1: Some air leakage will not affect braking
2: Components are light, compact and inexpensive to produce
3: Do not require bleeding
2 disadvantages of Air Brakes are
more susceptible to contamination and lag is unavoidable
Area = pi R squared or
Area = D squared x 0.7854
torque is measured in
lb-ft or N*m
Force is measure in
lb or N
Length is measured in
in or m
The foundation brake is
the mechanical side of the air brake system
What happens to temp. and pressure of gas when volume is compressed to half?
They are both doubled
What is purpose of air compressor?
To provide a supply of pressurized air for system operation
Purpose of governor?
Limit maximum air system pressure.
What Canadian law was enacted in the 1970’s?
CMVSS 121
