Key technical terms

Sep 26, 2019

Active safety: The (road-)handling technical equipment of a vehicle for the prevention of accidents, as opposed to èpassive safety.

Car2Car crashes: Crash test configurations with two vehicles instead of the more frequent constellation of vehicle against barrier or barrier against vehicle. In keeping with its safety philosophy of "Real-Life Safety", Mercedes-Benz has for many years examined the accident compatibility èof different road users in such Car2Car crash tests.

Crash test: Test in which the accident safety of a vehicle is examined during different types of collisions, e.g. head-on, side or rear impact and rollover tests.

Roof drop test: Mercedes-Benz in-house crash test that checks the rigidity of the roof, which is important in a rollover accident, for example. The vehicle body falls from a height of 50 centimetres and at a slight angle onto the roof structure, so that initially only one of the two A-pillars is stressed. In this load case, the test regulation only allows a defined plastic deformation in order to ensure the protective space.

Dummy: Life-size mannequin fitted with measuring technology, used in crash tests to record measurements. Based on the measured values, inferences about the injury risk of a person can be drawn.

Gravity (g): The acceleration experienced by a body on the earth's surface in free fall. 1 g = 9.81 m/s²

Euro NCAP (European New Car Assessment Programme): A consortium that has been conducting crash tests since 1997. At present, twelve institutions (ministries of transport, automobile clubs, insurance associations and research institutes) from eight European countries participate in this programme. New vehicles are assessed using a star-rating system. The test criteria are being advanced on a regular basis.

Compatibility: Relative vulnerability of different road users in Car2Car crashes. Smaller, lighter vehicles are at a physical disadvantage owing to the unequal mass ratio. In the event of a collision with a heavier vehicle, this can lead to high rates of deceleration. Mercedes-Benz always designs the body shell structure of large vehicles so that they are able to reduce the loads acting on smaller, lighter vehicles without compromising their own occupant protection.

Offset crash: Crash test configuration in which the vehicle only impacts an obstacle (vehicle or barrier) with part of its front section. Mercedes-Benz introduced the offset crash as a realistic in-house test method in 1979 on the basis of accident research findings. Today it is well established as a worldwide legal requirement. A distinction is made with regard to the percentage of overlap: for example, in a 50-percent offset crash, half of the vehicle strikes the other party involved in the accident (èsmall overlap test).

Passive safety: The constructional technical equipment of a vehicle for the mitigation of accident consequences, as opposed to èactive safety. The terms crash safety, accident safety and occupant protection also are used.

Post impact test: A special side impact configuration. The test vehicle is rammed sideways into a steel pillar on a test sled. The impact occurs at the head level of an adult dummy in the driver's seat. The resulting loads on e.g. the head, ribcage, abdomen, chest area and pelvis are measured and assessed.

"Real-Life Safety" philosophy: On its road to accident-free driving, Mercedes-Benz always takes its lead from what happens in real-life accidents, so as to protect all road users.

Rollover test: Crash test configuration in which the vehicle rolls over. The rollover test according to FMVSS208 is a legal requirement. The vehicle is mounted at an angle of 23° to the Y-axis on a sled, which is braked from 48.3 km/h. The vehicle is thrown off the sled and rolls over. In addition, Mercedes-Benz also uses inclined ramps to carry out rollover tests and a special ramp for a twisting somersault.

Sled test: In this crash simulation, a test sled is hydraulically or electrically accelerated and braked. A test object (vehicle body shell or assembly) is mounted on the sled and subjected to the forces arising during a real vehicle crash. Sled tests enable individual components or systems to be tested without destroying a vehicle.

Small overlap test: Crash test with a very small overlap (e.g. 25%), where only the width of passenger car's headlamp impacts an object head-on.

US NCAP (US New Car Assessment Programme): Manufacturer-independent crash test programme in the USA. Compared to the Euro NCAP, the crashes take place at different speeds against different barriers and from different angles. In addition, the programme differs in scope. Most crash tests in accordance with the US NCAP method are conducted by the National Highway Traffic Safety Administration (NHTSA), a US government agency. In C NCAP (China New Car Assessment Programme), a crash test programme modelled after the Euro NCAP is also in place in China.