Safety Restraint System

Restraint system

Holds vehicles occupants in their seat protecting them from injury during an accident. The restraint system includes the seat belts and the air bag system, as well as the vehicle’s body, frame, steering column and dash. Seat belts and airbags are required on all vehicles.

Crush ZonesLocated at the front and rear of the body-frame

assembly they are designed to collapse during a severe impact. Passenger compartment is stiffer and stronger then the crush zones, so occupants are protected from the forces of the accident.

Side impact beams

Are made of high strength steel, they are mounted in the vehicles doors to help prevent intrusion into the passenger compartment The A pillars and the B pillars are located in front and behind the doors, they extend up to the roof line. They are made of high strength steel and there job is to support the roof protecting the occupants in the case of a roll over.

Crash Tests

Are used by auto manufactures to determine how well the body and restraint system will protect the occupants in the case of a major vehicle collision. The manufacture will crash the vehicle into a wall or sometimes another vehicle to measure how well the vehicle withstands and reacts to the impact force.

Crash Test DummiesAre used to measure the impact forces acting upon the human body, sensors are placed at vital locations of the human body, they record the impact. Manufactures use this data to estimate the amount of injury a person would have sustained during a similar collision.

Active/Passive Restraints• Most injuries occur when the occupants are ejected from

their seats or from the passenger compartment upon impact.

• Active Restraint: Requires the occupants to ready the

system for example seatbelts that must be buckled manually.

• Passive Restraint: Operates without the occupants

activation the airbag system is automatically set when the vehicle ignition system has been activated

• (Example airbags or automatic seatbelts).

Seatbelts

Are made of nylon straps there function is to hold the occupant in their seat during a collision.

Seat belts also absorb energy by being designed to stretch during an impact, so that there is less speed differential between the passenger's body and their vehicle interior.

Also to spread the loading of impact on the passenger’s body.

Head Rest• Most drivers think headrests are just there for

comfort. They have a much more important purpose. When travelling in an automobile; a properly adjusted headrest can reduce the severity of neck injuries such as whiplash in the event of a collision. The top of the headrest should be in line with the top of the occupant's head.

• The headrest should not, however, be placed behind the occupant's neck.

Positioning of a head rest

• The top of a head restraint should reach at least as high as the top of your ear and be set back no more than 3 inches from your head

‘Third impact' after a passenger's body hits the car interior, airbag or seat belts, is that of the internal organs hitting the ribcage or skull.

The force of this impact is the mechanism through which car crashes cause disabling or life threatening injury

Show rear crash video

Seat belt styles

• There are two different style of belts Lap and shoulder belt.

• 1968 Federal law requires front seat belts for all passenger cars 1973 Federal law requires three-point lap-shoulder belts with inertia reels.

• 1984 First U.S. seat belt use law is enacted in New York

Seatbelt Pretension & retractor mechanism takes all of the slack out of the seatbelt so the belt fits snugly around the body.

Knee Diverter (knee Bolsters)

Is formed into the lower part of the dash to protect the driver’s and the front passenger’s knees from being injured on the metal dash.

The diverter also prevents the driver and passenger from sliding under the dash during a collision.

It’s usually a thick plastic panel that covers the metal framework of the dash panel

Airbag System

Automatically inflates large nylon bags immediately after a major collision. The air bag system is designed to supplement the protection of the seat belt.

The air bag inflates in 1/20th of a second long before the drivers body flies forward. The tough nylon bag can easily absorb the forward inertia of the occupant.

Airbag System

• The major parts of an air bag system are: • Air bag sensors: these are inertia sensors that

signal the control module in the event of a collision• Air bag module: contains the inflator mechanism

and the nylon air bag that expands to the occupants

• Air bag controller: computer that operates the system and runs diagnostic check every time the ignition has been activated.

• Dash warning lamps :dash bulb that glows with system problem and goes out as system arms as long as the R.C.M has not detected a fault

Air Bag types

All new vehicles are equipped with dual air bag for the front seat occupants. (In 1998, dual front airbags were mandated) second-generation air bags were also mandated.

This was due to the injuries caused by first-generation air bags that were designed to be powerful enough to restrain people who were not wearing seatbelts.

Driver’s Airbag

• The air bag module consists of a nylon bag and an igniter-inflator unit enclosed in a metal and plastic housing. The driver’s side air bag is packed into the steering wheel pad.

Passenger Airbag

The passenger side air bag deploys from the right side of the dash.

It is much larger then the driver side air bag because it has to protect two possible people simultaneously in the front seat.

The drivers and passenger dash mounted air bags will only deploy during a frontal impact.

A collision must occur with in 30 degrees of the vehicles centerline for it to inflate.

Side impact air bags

When a vehicle is hit from the side injury usually results from the occupant’s shoulder or head flying through the side window glass. The side impact sensors senses the side thrust of the impact and deploys a air bag located in the seat cushion.

Window air bag (curtain) is designed to drop down like curtains over the window glass. This helps protect the occupants from head and facial injuries caused by impact with the door glass.

Side-impact Protection

Canopy Airbag Seat Airbag

Show Video side impact

Questions1. How would you explain the main purpose of the Air bag

system?

The air bag system is designed to supplement the protection of the seat belt

2. How would you summarize third impact?

Internal organs hitting the ribcage or skull

3. Why did they, the manufacture choose to install side impact protection?

side injury usually results from the occupant’s shoulder or head flying through the side window glass