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4) Water Pump
The belt-driven centrifugal water pump consists of an impeller, a drive shaft, and a belt pulley.
The impeller is supported by a completely sealed bearing.
The water pump is serviced as an assembly and, therefore, cannot be disassembled.
5) Thermostat
A wax pellet-type thermostat controls the flow of the engine coolant through the engine cooling
system. The thermostat is mounted in the thermostat housing to the front of the cylinder head.
The thermostat stops the flow of the engine coolant from the engine to the radiator to provide
faster warm-up, and to regulate the coolant temperature. The thermostat remains closed while the
engine coolant is cold, preventing circulation of the engine coolant through the radiator. At this
point, the engine coolant is allowed to circulate only throughout the heater core to warm it quickly
and evenly.
As the engine warms, the thermostat opens. This allows the engine coolant to flow through the
radiator wherethe heat is dissipated. This opening and closing of the thermostat permits enough
engine coolant to enter the radiator to keep the engine within proper engine temperature operating
limits.
The wax pellet in the thermostat is hermetically sealed in a metal case. The wax element of the
thermostat expands when it is heated and contracts when it is cooled.
As the vehicle is driven and the engine warms, the engine coolant temperature increases. When
the engine coolant reaches a specified temperature, the wax pellet element in the thermostat
expands and exerts pressure against the metal case, forcing the valve open. This allows the
engine coolant to flow through the engine cooling system and cool the engine.
As the wax pellet cools, the contraction allows a spring to close the valve.
The thermostat begins to open at 82°C(180 °F) and is fully open at 95°C(203°F). The thermostat
closes at 80°C (176°F).
6) Electric Cooling Fan
Keep hands, tools, and clothing away from the engine cooling fans to help prevent personal
injury.
This fan is electric and can turn on even when the engine is not running. -
If a fan blade is bent or damaged in any way, no attempt should be made to repair or reuse
the damaged part. A bent or damaged fan assembly should always be replaced with a new
one to prevent possible injury. -
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2) Camber
The angle between the center line of the tire and the vertical line when viewed from the front of
the vehicle
CamberLH -0.19° ± 0.25°
RH -0.29° ± 0.25°
Positive camber: Top of the tire is tilted outward ▶
Advantages: The axle is not bent when it is loaded.
The force required to operate the steering wheel is reduced due to
smaller contact area (or load area) of the tire.
Restoring force of the steering wheel is gained (when turning the
steering wheel, the tire circles and the force to lift the frame is applied.
In this case, the shock absorber contracts and the restoration force is
applied to the steering wheel.) -
-
-
Disadvantages:Cornering force decreases as the positive camber increases when
the vehicle makes turn.
The hub bearing is worn unevenly if camber is excessive. -
-
Zero camber: When the tire center line is perpendicular to the ground level ▶
Negative camber ▶
Advantages:
Better traction force due to wide load area (applicable for off-road vehicle)
Better corner driving when the vehicle makes turn as the cornering force
increases (applicable for high-speed F1 vehicle) -
-
Disadvantages:
he axle is easy to be bent or deviated in the negative camber than in
the positive camber when load is applied on the axle.
Difficult to control due to wide load area. -
-
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2) Operation of ESP System
The ESP (Electronic Stability Program) has been developed to help a driver avoid danger of losing
control of the vehicle stability due to understeer or oversteer during cornering. The yaw rate
sensor, lateral sensor and longitudinal sensor in the sensor cluster and the steering wheel angle
sensor under the steering column detect the vehicle conditions when the inner or outer wheels are
spinning during oversteer, understeer or cornering. The ESP ECU controls against oversteer or
understeer during cornering by controlling the vehicle stability using input values from these
sensors and applying the braking force to the corresponding wheels independently. The system
also controls the engine power right before the wheel spin synchronized with the ASR function to
decelerate the vehicle automatically in order to maintain the vehicle stable during cornering.
(1) Under steering
What is understeering? ▶
Understeer is a term for a condition in which the steering wheel is steered to a certain angle during
driving and the front tires slip toward the reverse direction of the desired direction. Generally,
vehicles are designed to have understeer. It is because that the vehicle can return back to inside of
cornering line when the steering wheel is steered toward the inside even when the front wheels are
slipped outward.
As the centrifugal force increases, the tires can easily lose the traction and the vehicle tends to slip
outward when the curve angle gets bigger and the speed increases.
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ESP controls during understeer ▶
The ESP system recognizes the directional angle with the steering wheel angle sensor and senses
the slipping route that occurs reversely against the vehicle cornering direction during understeer
with the yaw rate sensor and lateral sensor. Then, the ESP system applies the braking force to the
rear inner wheel to compensate the yaw moment value. In this way, the vehicle does not lose its
driving direction and the driver can steer the vehicle as intended.
(2) Over steering
What is oversteering? ▶
Oversteer is a term of a condition in which the steering wheel is steered to a certain angle during
driving and the rear tires slip outward losing traction.
Compared to understeering vehicles, it is hard to control the vehicle during cornering and the
vehicle can spin due to rear wheel moment when the rear tires lose traction and the vehicle speed
increases.
ESP controls during oversteer ▶
The ESP system recognizes the directional angle with the steering wheel angle sensor and
senses the slipping route that occurs towards the vehicle cornering direction during oversteer
with the yaw rate sensor and lateral sensor. Then the ESP system applies the braking force to the
front outer wheel to compensate the yaw moment value. In this way, the vehicle does not lose its
driving direction and the driver can steer the vehicle as intended.