2012 SSANGYONG RODIUS change wheel

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3) HBA (Hydraulic Brake Assist System)
(1) Purpose
HBA (Hydraulic Brake Assist) system helps in an emergency braking situation when the driver
applies the brake fast, but not with sufficient pressure, which leads to dangerously long braking
distance. ECU recognizes the attempt at full braking and transmits the signal calling for full brake
pressure from the hydraulic booster. An inexperienced, elderly or physically weak driver may
suffer from the accident by not fully pressing the brake pedal when hard braking is required
under emergency. The HBA System increases the braking force under urgent situations to
enhance the inputted braking force from the driver.
Based on the fact that some drivers depress the brake pedal too soft even under when hard
braking is necessary, the HECU system is a safety supplementary system that builds high braking
force during initial braking according to pressure value of the brake pressure sensor and the
pressure changes of the pressure sensor intervals.
When the system is designed to apply high braking force when brake pedal is depressed softly by
an elderly or physically weak driver, the vehicle will make abrupt stopping under normal braking
situation due to high braking pressure at each wheels.

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(2) Operation
The brake pressure value and the changed value of the pressure sensor are the conditions in
which the HBA System operates. There are 2 pressure sensors under the master cylinder. When
the ESP ECU system determines that emergency braking is present, the pump operates, the
brake fluid in the master cylinder is sent to the pump and the braking pressure is delivered to the
wheels via the inlet valves.
If the drive depress the brake pedal slowly, the pressure change is not high. In this case, only the
conventional brake system with booster is activated.

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4. SCHEMATIC DIAGRAM
When equipped with ABS, the braking force at each wheel will be controlled with 3-channel 4-
sensor method. And when equipped with ESP, 4 wheels will be controlled independently with 4-
channel method. (When controlling ABS system only, it will be operated with 3-channel method.)
When compared to the vehicle equipped with ABS/EBD only, the internal hydraulic circuit has a
normally-open separation valve and a shuttle valve in primary circuit and in secondary circuit.
When the vehicle brakes are not applied during engine running or when applying the non-ABS
operating brakes, the normally-open separation valve and the inlet valve are open, whereas the
normally-closed shuttle valve and the outlet valve are closed. When the ESP system is operating,
the normally-open separation valve will be closed by the solenoid valve operation and the hydraulic
circuit will be established by the shuttle valve. Then, the inlet and outlet valves will be
closed or open depending on the braking pressure increase, decrease or unchanged conditions.
▶The warning lamp comes on and warning beep sounds when the ESP is operating
Driving feeling when the ESP is operating ▶
▶Noise and vibration that driver senses when the ESP is operating
1) Hydraulic Circuit Diagram
When the ESP operates during vehicle movement, the ESP warning lamp on the instrument
panel flickers and beep comes on every 0.1 seconds. The ESP operation shows that the vehicle
stability is extremely unstable and it is used to warn the driver. The ESP system is just a
supplementary system for the vehicle motion and it cannot control the vehicle when it exceeds
the physical limits. Do not solely rely on the system but be advised to drive the vehicle safely.
When the ESP system activates, the driving feeling can be different depending on vehicle
driving conditions. For example, you will feel differently when the ESP system is activated during
when ABS is operating with the brakes applied and when brakes are not applied on a curve.
Thus, the ESP system would make the driver feel more abruptly when the brakes are applied
during the ESP system activation.
The ESP system may transfer noise and vibration to the driver due to the pressure changes
caused by the motor and valve operations in a very short period of time. Extreme cornering will
trigger the ESP operation and this will make the driver feel noise and vibration due to sudden
brake application. Also, the ESP system controls the engine output. So, the driver may notice
the engine output decrease even when the accelerator pedal is being applied.

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(2) Hydraulic Circuit of HBA
The above figure shows one front and one rear wheel and the same hydraulic circuit forms as in
the ESP operation. When HECU recognizes that it is an emergency and it is required for hard
braking, depending on the pressure value of the brake pressure sensor and pressure changes
caused by the pressure sensor timing, it operates the pump immediately to apply the brake
pressure at the wheels. Then, the pressure in the pump increases until just before the
corresponding wheel gets locked. The motor still keeps rotating and the outlet valve and the
separation valve will stay closed. When the wheel starts to lock, the HBA function cancels and
switches to ABS operation.

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▶Pressure Decreases in the Circuit when ABS is Operating
Even when the hydraulic pressure on each circuit is stable, the wheel can be locked as the wheel speed
decreases. This is when the ABS ECU detects the wheel speed and the vehicle speed and gives the
optimized braking without locking the wheels. In order to prevent from hydraulic pressure increases, the
inlet valve is closed and the outlet valve is opened. Also, the oil is sent to the low pressure changer and
the wheel speed increases again. The ABS ECU operates the pump to circulate the oil in the low
pressure chamber to the master cylinder. This may make the driver to feel the brake pedal vibration and
some noises.
▶Pressure Increases in the Circuit when ABS is Operating
<0068009a0047009b008f008c0047009e008f008c008c00930047009a0097008c008c008b004700900095008a0099008c0088009a008c009a00530047009b008f008c0047009000950093008c009b0047009d00880093009d008c004700960097008c009500
9a004700880095008b0047009b008f008c0047009e008f008c>el’s pressure increases due to
the master cylinder pressure. The oil in the low pressure chamber circulates to the wheel by the pump
and the wheel speed decreases as the hydraulic pressure at wheel increases. This operation continues
repetitively until there are no signs that the ECU is locking the wheels. When the ABS hydraulic pressure
control takes place, there may be some vibration and noises at the brake pedal.

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Oil Level Check ▶
Check the fluid level on a level ground with the
engine turned off. The fluid level should be
between the MIN and MAX marks on the
reservoir cap gauge.
Place the vehicle on a level ground and start
the engine and let it run at idle speed.
Turn the steering wheel several times so that
the oil temperature reaches to normal
operating level (75~85˚C).
Place the steering wheel at straight ahead
direction.
Check the oil level in the power steering oil
reservoir. Adjust the oil level between MAX
and MIN. A.
B.
C.
D.
Oil Change ▶
If the difference between two measurements
is below 5 mm and the level is between MAX
and MIN level, it's normal. If it is over 5 mm,
bleed air from the system.
Open the power fluid reservoir cap and drain
the fluid completely with oil suction device.
To make it easy, turn the steering wheel to its
both ends several times.
Fill up the specified fluid into fluid reservoir
and bleed air from the steering system. A.
B.
Oil typeS-PSF3
Capacityapprox. 1.1ℓ
(including reservoir)
below 5
mm
Engine running Engine idling