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Glossary of Terms P-Q A|B|C|D|E|F|G|H|I|J|K|L|M|N|O|P|Q|R|S|T|U|V|W|X|Y|Z PA - pressure angle PD - pitch diameter Pinion - When considering two sprockets or gears that run together the one with the smaller number of teeth is called the pinion. Pitch - In general terms, pitch is a measure of the size of the teeth of a sprocket or gear. It is the distance between two teeth at the pitch diameter. The larger the pitch, the larger the teeth. Several systems are used to designate pitch in gears, such as Diametral Pitch, Circular Pitch and Module. In describing sprockets a number (e.g. - 35, 120, 2040) designates the pitch, as well other defining dimensions of the sprocket and chain. Pitch Angle - is the angle between an element of a pitch cone and its axis. Pitch Diameter (PD) - is the diameter of the pitch circle. In parallel shaft gears, the pitch diameters can be determined directly from the center distance and the number of teeth by proportionality. Operating pitch diameter is the pitch diameter at which the gears operate. Pitch Diameter of a Sprocket - The circle traced by the path of the chain pin centers as the chain travels around the sprocket. Plain Bore - This term is used to indicate that the center hole in a sprocket or gear has no keyway, set screw(s), bushing or any other type of machined preparation for shaft mounting. Plain bores may be machined to a specified tolerance or a nominal tolerance. Plain bores are also referred to as mandrel bores or stock bores. Pressure Angle (PA) - is the angle between a tooth profile and the radial line at its pitch point. In involute teeth, pressure angle is often described also as the angle between the line of action and the line tangent to the pitch circle. Standard pressure angles are established in connection with standard gear-tooth proportions. Q.D.® - is a Registered Trademark of Emerson Electric Co., stands for Quick Detachable and refers to a split-tapered bushing system. |