Three body styles with pillars and boxes

The pillars on a

car A car, or an automobile, is a motor vehicle with wheels. Most definitions of cars state that they run primarily on roads, seat one to eight people, have four wheels, and mainly transport people rather than cargo. There are around one billio ...

with permanent roof body style (such as four-door

sedans A sedan (American English) or saloon (British English) is a passenger car in a three-box configuration with separate compartments for an engine, passengers, and cargo. The first recorded use of ''sedan'' in reference to an automobile body oc ...

) are the vertical or nearly vertical supports of its window area or

greenhouse A greenhouse is a structure that is designed to regulate the temperature and humidity of the environment inside. There are different types of greenhouses, but they all have large areas covered with transparent materials that let sunlight pass an ...

—designated respectively as the A, B, C and (in larger cars such as 4-door

station wagon A station wagon (American English, US, also wagon) or estate car (British English, UK, also estate) is an automotive Car body style, body-style variant of a Sedan (automobile), sedan with its roof extended rearward over a shared passenger/cargo ...

s and

sport utility vehicle A sport utility vehicle (SUV) is a car classification that combines elements of road-going passenger cars with features from off-road vehicles, such as raised ground clearance and four-wheel drive. There is no commonly agreed-upon definitio ...

s) D-pillar, moving from front to rear, in profile view.

Nomenclature

Car pillars are vertical or inclined components of an enclosed automobile's body that both support its roof and reinforce the torsional rigidity of the body. An alphabetical convention for designating a car's pillars has developed over time, used variously by the automotive press in describing and reviewing vehicles, insurance companies in identifying damaged components, and first-responder rescue teams to facilitate communication, as when using the jaws of life to cut their way into a wreck. The letters A, B, C, and D are used (in upper case): * The A-pillar is the forward-most pillar on a vehicle, supporting its roof at each corner of the windshield. * The B-pillar is located between a vehicle's front and rear side glass, where it serves as a structural support of its roof. * The C-pillar is the rearmost on two- and four-door sedans and hatchbacks. * The D-pillar is the rearmost pillar on larger four-door vehicles such as station wagons and full-sized SUVs. Posts for quarter windows (a smaller typically opening window on older vehicles between the front door window and windshield, and sometimes found in the rear, usually fixed) are not considered roof pillars.

Design

Body pillars are critical in providing strength to an automobile body. As the most costly body components to develop or re-tool, a vehicle's roof and door design are a major factor in meeting safety and crash standards. Before safety standards, pillars were typically thin. The design of body pillars has changed with regulations that provide roof crush protection. Standards in the United States were introduced in phases starting in 2009 that require enclosed passenger cars to be able to support from 1.5-times to 3.0-times the vehicle's unloaded weight on its roof while maintaining headroom (survival space) for occupants. This has meant designing thicker roof pillars that not only provide sufficient strength, but that also incorporate padding and accommodate

airbag An airbag is a vehicle occupant-restraint system using a bag designed to inflate in milliseconds during a collision and then deflate afterwards. It consists of an airbag cushion, a flexible fabric bag, an inflation module, and an impact sensor. ...

s. However, because thicker A-pillars can somewhat limit the driver's forward field of vision and thus create blind spots, some designs employ slimmer,

chamfer A chamfer ( ) is a transitional edge between two faces of an object. Sometimes defined as a form of bevel, it is often created at a 45° angle between two adjoining right-angled faces. Chamfers are frequently used in machining, carpentry, fur ...

ed A-pillars made of stronger

alloy steel Alloy steel is steel that is Alloy, alloyed with a variety of elements in amounts between 1.0% and 50% by weight, typically to improve its List of materials properties#Mechanical properties, mechanical properties. Types Alloy steels divide into ...

on each side of the windshield to help improve driver vision while still meeting safety standards and offering crash protection. One of the important design elements of modern cars is the A-pillar because its location and angle impact the shape of the front of the car and the overall shape of modern vehicles or what designers call "volume." For example, more forward positioned A-pillars provide for increased interior room and make for less angle and visual difference between the hood and windshield. This arrangement makes the side view of a car look aerodynamic. The A-pillars that are positioned further back on a vehicle are most often found on rear-wheel drive and SUV models. This arrangement provides a greater hood to windshield angle as well as achieving a bigger field of view for the driver, but at the disadvantage of encroaching on interior space. The center B-pillar on four-door sedans (also known as a "post") is typically a closed steel structure welded at the bottom to the car's

rocker panel A glossary of terms relating to automotive design. Some terms may be found at car classification. 0–9 ; One-box form: A categorization based on overall form design using rough rectangle volumes. In the case of the one-box, also called a m ...

and floorpan, as well as on the top to the roof rail or panel. This pillar provides structural support for the vehicle's roof panel and is designed for latching the front door and mounting the

hinge A hinge is a mechanical bearing that connects two solid objects, typically allowing only a limited angle of rotation between them. Two objects connected by an ideal hinge rotate relative to each other about a fixed axis of rotation, with all ...

s for the rear doors. As "perhaps the most complex of all the structures on the vehicle", the B-pillar may be a multi-layered assembly of various lengths and strengths. B-pillars also exist as integral elements of an automobile

unibody A vehicle frame, also historically known as its ''chassis'', is the main supporting structure of a motor vehicle to which all other components are attached, comparable to the skeleton of an organism. Until the 1930s, virtually every car had ...

on two-door sedans and hatchbacks, separating the front door from either fixed or movable glass of the second row of seating. Additional doors beyond four, such as on

limousine A limousine ( or ), or limo () for short, is a large, chauffeur-driven luxury vehicle with a partition between the driver compartment and the passenger compartment which can be operated mechanically by hand or by a button electronically. A luxu ...

s, will create corresponding B-pillars, numbered by order B1, B2, etc.. Closed vehicles without a B-pillar are widely called

hardtop A hardtop is a rigid form of automobile roof, typically metal, and integral to the vehicle's design, strength, and style. The term typically applies to a pillarless hardtop, a car body style without a B-pillar. The term "pillared hardtop" was ...

s and have been available in two- or four-door body styles, in sedan, coupe, and station wagon versions. Designs without a "B" pillar for roof support behind the front doors and rear side windows offer increased occupant visibility, while in turn requiring underbody strengthening to maintain structural rigidity. The need for stronger roof structures meant replacing the pillar-less designs with a rigid B-pillar such as the two-door

AMC Matador The AMC Matador is a series of mid- and full-size automobiles produced by American Motors Corporation (AMC) from 1971 through 1978 model years. Initially positioned as a mid-size family car, the Matador spanned two distinct generations: the fir ...

line. To continue capitalizing on the popularity of the design, General Motors attempted to broaden the definition of "hardtop" during the early 1970s to include models with a B-pillar, with the false rationale, "up to then, everybody thought a hardtop was a car without a center pillar." The "Colonnade" mid-sized General Motors models were so named because of their pillared structure designed to meet new rollover protection standards, but marketers attempted to promote them as if they were true hardtops. By the late 1970s (1978 being the last year of pillarless hardtop cars in the U.S. domestic market), the full-size

Chrysler Newport The Newport was a name used by Chrysler for both a hardtop body designation and also for its lowest priced model between 1961 and 1981. Chrysler first used the Newport name on a 1940 show car, of which five vehicles were produced. From 1950 to ...

and

New Yorker New Yorker may refer to: * A resident of New York: ** A resident of New York City and its suburbs *** List of people from New York City ** A resident of the New York (state), State of New York *** Demographics of New York (state) * ''The New Yor ...

were the last designs with opening front and rear side windows and no B-pillar. The C-pillar is the rearmost on two- and four-door sedans and hatchbacks, and has served as an opportunity for automobile designers "to introduce a little 'design flair' to what would otherwise be a fairly nondescript side view." Most conventional C-pillars are rearward sloping, but reverse-angled have been used to differentiate their designs. Because many modern cars are similar in side view, the designs of the C-pillar have "become an area for stylistic whimsy." Designs of the D-pillar typically found on station wagons and SUVs have also undergone a transition from function to more of a styling element. As crossover vehicles look similar, "the D-pillar is the only opportunity for any distinction."

References

External links

"Art of Automotive C Pillars"
��Flickr photo group created 26 July 2005; webpage accessed 26 June 2022. {{Automobile configuration Automotive body parts Automotive styling features Vehicle safety technologies sv:Kaross#A-stolpe

Nomenclature

Design

See also

References

External links