Lochkreise
Lochkreise refers to the circle on which the centers of holes for fasteners are located in a mounting pattern. It is a fundamental concept in mechanical engineering and is used for wheels, flanges, gears, pulleys, and machine beds. The circle is defined by its diameter, known as Lochkreismaß in German, and is commonly called the pitch circle diameter (PCD) in international contexts. The pattern is described by the number of holes and the diameter of the circle, often written as z × D, for example 5 × 114.3 mm or 4 × 100 mm.
The holes are typically evenly spaced around the circumference and lie on the same circle. The PCD
In practice, Lochkreise is used not only for wheels but for any mounting pattern requiring alignment of
In English, the term is bolt circle or pitch circle diameter (PCD). See also bolt pattern, PCD,