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Gear-Cutting Machines and Operations
Published in Helmi Youssef, Hassan El-Hofy, Traditional Machining Technology, 2020
Gears are machine elements that transmit power and rotary motion from one shaft to another. An advantage they have over friction and belt drives is that they are positive in their action, a feature that most of the machine tools require, as exact speed ratios are sometimes essential. Thread cutting and indexing movements in gear cutting are typical examples, which require synchronized rotary and linear movements without any slip. As drive elements, gears are specifically used to Change the speed of rotationChange the direction of rotationIncrease or reduce the magnitude of speed and torqueConvert rotational movement into linear, or vice versa (rack and pinion drive)Change angular orientation (bevel gears)Offset the location of rotating movement (helical gears and worm gear sets)
Tolerancing
Published in Ken Morling, Stéphane Danjou, Geometric and Engineering Drawing, 2022
If the two tolerance intervals overlap each other so that the internal mating part could be smaller or larger than the external mating part, then this is a transition fit. Depending on the actual sizes of the two mating parts, it can result in a very small clearance or in a small interference. Transition fits are used when accurate location is required. Examples are machine elements on a shaft such as gears, pulleys and bearings.
Bearings
Published in Keith L. Richards, Design Engineer's Sourcebook, 2017
A bearing is a machine element that allows one part to bear on another part, and allows easy movement between the two parts. A bearing constrains relative motion and reduces friction between moving parts. The design of the bearing may provide axial movement of the part or rotational around a fixed axis.
Objects as Carriers of Engineering Knowledge
Published in Engineering Studies, 2022
The notion of schematic design chunk encompasses a range of narrower concepts familiar to designers in different fields. Engineers make use of the concept of ‘machine element’ for generic elements that are used in multiple machines, such as bearings. They also use the far more abstract concept of ‘solution principle’ for how a part of a machine can carry out a particular function, for example diesel engines and electric motors are different solution principles to provide propulsion. We want the notion of schematic design chunk to cover both solution principles and concrete embodiments of them, thus both the idea of a ball bearing, and knowledge of the characteristics of a particular ball bearing supplied by a particular manufacturer.