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Glossary of Terms M-N-O 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 MD - mounting distance MH - max. hub (maximum allowable hub diameter) MOD - module, the pitch of a metric gear Mandrel 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. Mandrel bores may be machined to a specified tolerance or a nominal tolerance. Mandrel bores are also referred to as plain bores or stock bores. Milled-To-Match - This is a process of machining the ends of gear racks so that they may be mounted end-to-end with pitches running continuously across sections. A pinion may run across multiple sections of milled-to-match racks without interruption. Gear rack ends are normally sawed and may not be mounted this way without additional processing. Miter Gears - are mating bevel gears with equal numbers of teeth with axes, usually at right angles. Module (MOD) - the ratio of the pitch diameter in millimeters to the number of teeth; a measurement of gear pitch expressed in metric Maximum Allowable Hub Diameter (Max. Hub) - the maximum diameter that will clear below the sidebars of a chain when wrapped around a sprocket. If the hub diameter required for an application exceeds the max. hub of the desired sprocket a chain-recess style hub can be used. This is a hub which is below max. hub diameter at the sprocket face, then steps up to a larger diameter at a distance from the face that allows chain sidebar clearance. The larger diameter hub area is used for installation of set screws or oversized bushings. Mounting Distance (MD) - is the distance, for assembling bevel gears or hypoid gears, from the crossing point of the axes to a location surface of a gear, which may be at either back or front. OD - outside diameter Operating Pitch Diameters - are the pitch diameters determined from the numbers of teeth and the center distance at which gears operate. Outside Diameter (OD) - the diameter of the circle which contains the tops of the teeth of an external gear or sprocket. |