2007 SSANGYONG RODIUS Service Manual

0-17
ESP SYSTEM
RODIUS 2006.09
4892-01
▶When applied ABS (maintained pressure)
The Inlet valve and outlet valve will be closed to maintain the pressure in the hydraulic circuit
applied at the wheels. By closing the valves, the hydraulic pressure at the wheels will not be
lost or supplied any more. During ESP operation, the separation valve closes and only the
shuttle valve at the pump opens.

0-18
RODIUS 2006.09
4892-01
ESP SYSTEM
▶When applied ABS (increased pressure)
The shuttle valve and inlet valve will be open and the separation valve and outlet valve will be
closed. Then, the pump is operated.
When ESP operates while the ABS is operating, the pressure will be increased continuously
until just before the corresponding wheel gets locked.

0-19
ESP SYSTEM
RODIUS 2006.09
4892-01
▶Hydraulic Diagram 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 are will stay closed.
When the wheel starts to lock, the HBA function cancels and switches to ABS operation.

0-20
RODIUS 2006.09
4892-01
ESP SYSTEM
4. ELECTRICAL CIRCUIT DIAGRAM
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0-21
ESP SYSTEM
RODIUS 2006.09
4892-01
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0-3
ABS SYSTEM
RODIUS 2006.09
4892-01
4892-01ABS
1. SPECIAL TOOLS AND EQUIPMENT

0-4
RODIUS 2006.09
4892-01
ABS SYSTEM
2. GENERAL INFORMATION
The aim of the ABS is to mmaintain steerability and driving stability and to take the burden off
the driver. If the stopping distance is shorter on some road surfaces (carriageway conditions),
this is a gift of physics and not a development aim.
ABS is a device which senses that one or more of the wheels are locking up during braking. It
monitors the rotational speeds of the wheels and reduces hydraulic pressure to any wheel it
senses locking up. It is controlled by both mechanical and electronic components. When you
apply the brakes, the ABS will regulate the flow of brake fluid being delivered to the brake
calipers. By the use of electronic computers, the brakes rapidly alternate (at a rate of 30 times
per second) from full pressure to full release.
1) DRIVING PHYSICS
To give you a better understanding of the tasks and functions of ABS, we will first look at the
physics principles.
(1) The Stopping Distance
The stopping distance depends on the vehicle weight and initial speed when braking starts.
This also applies for vehicle with ABS, where ABS always tries to set an optimum brake force
on each wheel. As great forces are exerted between the tires and the carriageway when
braking, even with ABS the wheels may scream and rubber is left on the road. With an
ABS
skid mark one may be able to clearly recognize the tire profile. The skid mark of an ABS vehicle
does not however leave any hint of the speed of the vehicle in the case of an accident, as it can
only be clearly drawn at the start of braking.
(2) Brake Force on a Wheel
The maximum possible brake force on a wheel depends on the wheel load and the adhesion
coefficient between tire and carriageway. With a low adhesion coefficient the brake force, which
can be obtained is very low. You are bound to know the result already from driving on winte
r
roads. With a high adhesion coefficient on a dry road, the brake force, which can be obtained,
is considerably higher. The brake force, which can be obtained, can be calculated from below
formula:

0-5
ABS SYSTEM
RODIUS 2006.09
4892-01
Maximum brake force ▶
FBmax = Vehicle Weight x Adhesion
coefficientmh
The braking process cannot be described
sufficiently accurately with the brake forces
calculated. The values calculated only apply
if the wheel is not locked. In the case of a
locking wheel, the static friction turns into
lower sliding friction, with the result that the
stopping distance is increased. This loss of
friction is termed “slip” in specialist
literature.
Slip ▶
The brake slip is the difference between the vehicle speed and the wheel circumference speed.
If the wheel locks, the slip is greatest, that is 100 %. If the wheel is running freely and unbraked,
the slip is the lowest, equal to 0 %. Slip can be calculated from the vehicle speed Vveh and the
wheel speed Vw. The equation for this is:
S = X 100 %
Vveh = 100 km/h, Vw = 70 km/h
S = X 100 %
The slip is 30 %.
Vveh - Vw
Vveh
100 - 70
100