"Pitch circle diameter" redirects here. For the effective distance between gears, see Pitch circle diameter (gears).
Drawing of 5-hole (left) and 4-hole (right) pitch circles
A bolt circle diameter or pitch circle diameter (PCD), sometimes simply called bolt circle or pitch circle, is a common term for when a number of screw holes for bolts are evenly distributed with their centers along an imaginary circle with a given diameter.
An example of use is mounting of car rims, where the bolt circle is one of several factors that determine whether a set of rims will fit a car. For example, a bolt circle of 5×130 or 5-130 indicates that a rim is to be attached to the car via 5 screws evenly spaced along a circle with a diameter of 130 millimeters.[1] Other common uses for bolt circles are for indicating mounting for sim racing and real-world car steering wheels, or in the industry for mounting of servomotors or for specifying the bolt pattern of a flange. Attachment of chain rings for bicycle cranksets are also specified by a bolt circle.[2]
Examples
Racing wheels
On steering wheels for cars utilizing bolt circles, this usually measures 6×70mm.[3] Some racing wheels attach to the car via a quick release hub,[4] and this hub then usually has a corresponding bolt circle of 6×70mm. Example of other less used patterns include: 3×1.75in (44.45mm), 5×2.75in (69.85mm), 6×74mm and 6×2.75in (69.85mm).[3]
Servomotors
Industrial servomotors and gearboxes, with standardised flange mountings for interchangeability.
Servomotors in the industry are often mounted via a flange-like coupling to give the shortest possible leverage for high-torque uses. Industrial servomotors often use standardised mounting patterns, of which one example is a bolt circle of 4×130mm diameter (approximately corresponds to a square pattern of 91.9mm × 91.9mm).
The mounting pattern of most car rims are described using bolt patterns, and this pattern is one of many factors which determine whether a rim will fit a given car. Here, the bolt circle indicates the number of wheel nuts and associated hub bolts (or alternatively just wheel bolts).[5][6]
An example of a bolt circle is 5×100 which indicates 5 nuts placed on a circle with a diameter of 100mm. Some of the most common bolt circle diameters on modern cars are 100mm, 112mm and 114.3mm.[citation needed] The bolt circle of a car is one of several parameters that must be checked before buying new rims to make sure they will fit the car (along with wheel offset, hub diameter, and finally the diameter and width of the rim and tire). Over the years, over 30 different bolt circles patterns have been used by car manufacturers,[7] most of which are not compatible with each other.
A flange is a protruded ridge, lip or rim, either external or internal, that serves to increase strength ; for easy attachment/transfer of contact force with another object ; or for stabilizing and guiding the movements of a machine or its parts. Flanges are often attached using bolts in the pattern of a bolt circle.
A spoke is one of some number of rods radiating from the center of a wheel, connecting the hub with the round traction surface.
A bicycle wheel is a wheel, most commonly a wire wheel, designed for a bicycle. A pair is often called a wheelset, especially in the context of ready built "off the shelf" performance-oriented wheels.
The crankset or chainset is the component of a bicycle drivetrain that converts the reciprocating motion of the rider's legs into rotational motion used to drive the chain or belt, which in turn drives the rear wheel. It consists of one or more sprockets, also called chainrings or chainwheels attached to the cranks, arms, or crankarms to which the pedals attach. It is connected to the rider by the pedals, to the bicycle frame by the bottom bracket, and to the rear sprocket, cassette or freewheel via the chain.
A hubcap or hub cap is a decorative disk on an automobile wheel that covers at minimum the central portion of the wheel, called the hub. An automobile hubcap is used to cover the wheel hub and the wheel fasteners to reduce the accumulation of dirt and moisture. It also has the function of decorating the car.
A steering wheel is a type of steering control in vehicles.
The wheel size for a motor vehicle or similar wheel has a number of parameters.
Wheelbuilding is the process of assembling wire wheels. The components of a wire wheel are the rim, spokes, nipples, and hub.
On a bicycle, the cassette or cluster is the set of multiple sprockets that attaches to the hub on the rear wheel. A cogset works with a rear derailleur to provide multiple gear ratios to the rider. Cassettes come in two varieties, freewheels or cassettes, of which cassettes are a newer development. Although cassettes and freewheels perform the same function and look almost the same when installed, they have important mechanical differences and are not interchangeable.
The rim is the "outer edge of a wheel, holding the tire". It makes up the outer circular design of the wheel on which the inside edge of the tire is mounted on vehicles such as automobiles. For example, on a bicycle wheel the rim is a large hoop attached to the outer ends of the spokes of the wheel that holds the tire and tube. In cross-section, the rim is deep in the center and shallow at the outer edges, thus forming a "U" shape that supports the bead of the tire casing.
A lug nut or wheel nut is a fastener, specifically a nut, used to secure a wheel on a vehicle. Typically, lug nuts are found on automobiles, trucks (lorries), and other large vehicles using rubber tires.
Wire wheels, wire-spoked wheels, tension-spoked wheels, or "suspension" wheels are wheels whose rims connect to their hubs by wire spokes. Although these wires are considerably stiffer than a similar diameter wire rope, they function mechanically the same as tensioned flexible wires, keeping the rim true while supporting applied loads. The term suspension wheel should not be confused with vehicle suspension.
The ISO metric screw thread is the most commonly used type of general-purpose screw thread worldwide. They were one of the first international standards agreed when the International Organization for Standardization (ISO) was set up in 1947.
Wheel studs are the threaded fasteners that hold on the wheels of many automobiles. They are semi-permanently mounted directly to the vehicle hub, usually through the brake drum or brake disk. Lug nuts are fastened onto the wheel stud to secure the wheel. When a wheel is removed for tire changes etc., the stud remains in the hub.
The steel wheel of a steam locomotive and other older types of rolling stock were usually fitted with a steel tire or tyre to provide a replaceable wearing element on a costly wheel.
A screw and a bolt are similar types of fastener typically made of metal and characterized by a helical ridge, called a male thread.
TETRIX Robotics consists of two robotic kits by Pitsco Education. The two sets are the TETRIX MAX building system and the TETRIX PRIME building system. They are intended to be used as educational robotics and for competitions such as the FIRST Tech Challenge.
A centerlock wheel is a type of automobile wheel in which the wheel is fastened to the axle using a single, central nut, instead of the more common ring of 4 or 5 lug nuts or bolts.
A direct-drive simulator steering wheel is a simulator steering wheel with a direct-drive mechanism between the drive and output, i.e. without gearing, and is used similarly as with other simulator steering wheels for providing torque feedback so that the driver, through movement in the steering wheel, gets an interface for sensing what is happening to the car in the simulator. It is an example of human-machine interaction in driving simulators, racing simulators and racing video games, and is an example of haptic technology
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.
