Q:

# What is pitch circle diameter?

A:

Pitch circle diameter is a term used to describe the centerline diameter of a circular bolt spacing, the diameter of theoretical friction discs that would transmit the same velocity ratio as two meshing gears, or the diameter at which the thread tooth equals the thread spacing for screw threads. Context should be used to determine whether the term is being used to describe bolt spacing, gears or threads.

Know More

For bolt or screw spacing, pitch circle diameter or PCD, also called the bolt circle diameter or BDC, is the diameter of an imaginary circle passing through the center of bolts distributed around a component such as a wheel, hub or housing. Once the pitch circle diameter is established, one need only specify the number of holes or threads and dimensions of each hole or thread to describe the full bolt pattern.

For two meshing gears, the pitch circle diameter represents each of two imaginary friction discs that, when spun together without slippage, would result in the identical velocity ratio and gear ratio as the actual gears. The pitch circle diameter is thus an important geometrical term for engineers in describing the mechanical relationship of a gear set.

To accurately measure the pitch circle diameter or pitch diameter of a thread requires either an optical comparator measuring device or thread wires.

## Related Questions

• A:

Atmosphere is a term used in literature to describe the mood of a piece of writing, which is usually created by how the author describes the setting and background, as well as the characters and events within the story. The author creates his or her atmosphere in order to give the reader subconscious impressions about the narrative.

Filed Under:
• A:

Result oriented is a term used to describe an individual or organization that focuses on outcome rather than process used to produce a product or deliver a service. As such, a number of processes are used where the most effective and economical process is identified.

Filed Under:
• A:

Escape conditioning is the term used to describe a subject's or animal's avoidance of stimuli, usually as a result of negative experiences, which leads to the behavior. If a person had a bad experience while swimming in the ocean, for example, leaving or avoiding any situation that involved going into the ocean again is a form of escape conditioning.

Filed Under:
• A:

Centrifugal force is a term used to describe an imaginary concept that states that during circular motion people and objects are pulled outward from the center, which in fact is caused entirely by inertia. Examples of this inertial phenomenon include cargo swaying when a truck takes a turn and mud flying from a spinning wheel.