TIAGO

SUPPLEMENTARY RESTRAINT SYSTEM (SRS)

11.1.2. WORKING OF RESTRAINTS

A. RESTRAINTS WITHOUT AIRBAGS

This restraint systems falls under the category of

Primary restraint systems.

PRIMARY RESTRAINT SYSTEM

Seat belts are known as primary restraints systems

as they provide the basic safety to occupants

during driving or accidents.

WORKING

The basic purpose of seat belts is to control

occupant movement inside the vehicle during

driving conditions, abrupt braking or accidents.

They help in avoiding or reducing the contact

severity of occupants with vehicle interiors.

It is necessary to wear the seat belts by the

occupants before starting to drive the vehicle. The

seat belts have a retractor mechanism which

ensures only the required seat belt webbing length

is available for occupant usage. This reduces the

risk of any loose webbing over the body of

occupants. The seat belts have a locking

mechanism which gets activated in relevant

conditions thereby preventing any loose belt

webbing to come out of retractor. This

phenomenon helps in controlling occupant

movement inside the vehicle.

COMPONENTS

1. Seat belt

2. Micro switch

3. Indicator lamp in cluster

B. RESTRAINTS WITH AIRBAGS

This restraint system falls under the category of

Supplementary restraint system.

SUPPLEMENTARY RESTRAINT SYSTEM

(SRS)

Air bags are the secondary restraint system as no

action is required by the vehicle occupant for the

activation of air bags.

!! WARNING

Seat belts shall be worn by every occupant when

ever they ride a vehicle. This is applicable whether

a vehicle is equipped with supplementary restraints

systems (SRS) or not.

WORKING OF SRS

Whenever there is an accident the sensor mounted

remotely sends crash signal to the ECU. The type

of accident and its severity, determines the time-to-

fire different airbags in the system. The basic

function of an airbag is to provide cushioning effect

to occupants in case of medium or severe

accident.

There are remote sensors mounted for sensing

different frontal and side accidents. These sensors

are connected to the electronic control unit (ECU)

of the system. When an accident event input signal

crosses a pre-defined threshold level in ECU, the

ECU triggers the relevant restraints components in

the system. This helps in providing necessary

protection to occupants. The airbags and seat belt

pretensioner get triggered through ECU signal.

The load limiter in the seat belts is a mechanical

device which gets activated when the forces on the

occupant upper body region crosses a defined

force threshold limit.

!! WARNING

Only the vehicles fitted with airbags should be

fitted with RPLL seat belts.

COMPONENTS

1. ECU

2. Front Remote Sensing Unit

3. Air bags



Driver air bag



Passenger air bag

4. RPLL

5. Clock spring

6. Airbag warning lamp

7. Airbag warning labels