Boltcirkel

Boltcirkel is a term used in engineering and mechanics to describe the diameter of an imaginary circle upon which the bolt holes of a wheel, hub, or flange are centered. It is a crucial measurement for ensuring that components fit together correctly. The bolt circle diameter is typically specified in millimeters (mm) or inches. It is often abbreviated as PCD (Pitch Circle Diameter) or BCD.

To determine the bolt circle diameter, one measures the distance between the centerlines of two opposing bolt holes. If there is an odd number of bolt holes, the measurement is taken from the center of one bolt hole to the center of another, and then the distance from that second hole to the center of the next hole is measured. Geometric calculations are then used to find the diameter of the circle that passes through the center of all bolt holes. This measurement is critical for automotive wheels, where it must match the bolt pattern of the vehicle's hub. Similarly, it is important for pipe flanges, brake rotors, and other rotating components. An incorrect bolt circle diameter will prevent a secure and proper fit, potentially leading to vibrations, uneven wear, or even catastrophic failure.