Pillar (car)

Pillars are the vertical or near vertical supports of a car's window area or greenhouse—designated respectively as the A, B, C or (in larger cars) D-pillar, moving from the front to rear, in profile view.

The consistent alphabetical designation of a car's pillars provides a common reference for design discussion and critical communication. As an example, rescue teams employ pillar nomenclature to facilitate communication when cutting wrecked vehicles, as when using the jaws of life.

In American and British English, the pillars are sometimes referred to as posts (A-post, B-post etc.).

Design

In the case of the B (or center) pillar on four-door sedans, the pillar is typically a closed steel structure welded at the bottom to the car's rocker panel and floorpan, as well as on the top to the roof rail or panel. This pillar provides structural support the vehicle's roof panel, as well as designed for latching the front door and mounting the hinges for the rear doors.

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. Some designs employ slimmer, chamfered windscreen pillars, A pillars, to help improve driver vision (thus reducing blind spots) through the use of stronger alloy steel in these components. As "perhaps the most complex of all the structures on the vehicle", the center or B-pillar may be a multi-layered assembly of various lengths and strengths.