Gear
![Iron gears, [[Han dynasty](https://upload.wikimedia.org/wikipedia/commons/7/73/Han_Iron_Gears_%289947881746%29.jpg)
The smaller member of a pair of meshing gears is often called pinion. Most commonly, gears and gear trains can be used to trade torque for rotational speed between two axles or other rotating parts and/or to change the axis of rotation and/or to invert the sense of rotation. A gear may also be used to transmit linear force and/or linear motion to a rack, a straight bar with a row of compatible teeth.
Gears are among the most common mechanical parts. They come in a great variety of shapes and materials, and are used for many different functions and applications. Diameters may range from a few μm in micromachines, to a few mm in watches and toys to over 10 metres in some mining equipment. Other types of parts that are somewhat similar in shape and function to gears include the sprocket, which is meant to engage with a link chain instead of another gear, and the timing pulley, meant to engage a timing belt. Most gears are round and have equal teeth, designed to operate as smoothly as possible; but there are several applications for non-circular gears, and the Geneva drive has an extremely uneven operation, by design.
Gears can be seen are instances of the basic lever "machine". When a small gear drives a larger one, the mechanical advantage of this ideal lever causes the torque ''T'' to increase but the rotational speed ''ω'' to decrease. The opposite effect is obtained when a large gear drives a small one. The changes are proportional to the ''gear ratio'' ''r'', the ratio of the tooth counts. namely, ''T''2/''T''1 = ''r'' = ''N''2/''N''1'', and ''ω''2/''ω''1 = 1/''r'' = ''N''1/''N''2''. Depending on the geometry of the pair, the sense of rotation may also be inverted (from clockwise to anti-clockwise , or vice-versa).
Most vehicles have a transmission or "gearbox" containing a set of gears that can be meshed in multiple configurations. The gearbox lets the operator vary the torque that is applied to the wheels without changing the engine's speed. Gearboxes are used also in many other machines, such as lathes and conveyor belts. In all those cases, terms like "first gear", "high gear", and "reverse gear" refer to the overall torque ratios of different meshing configurations, rather than to specific physical gears. These terms may be applied even when the vehicle does not actually contain gears, as in a continuously variable transmission. Provided by Wikipedia
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41by Yassin, G., Ade, P. A. R., Calderon, C., Challinor, A. D., Dunlop, L., Gear, W. K., Goldie, D. J., Grainge, K. J. B., Griffin, M. J., Jones, M. E., Lasenby, A. N., Maffei, B., Mauskopf, P. D., Melhuish, S. J., Orlando, A., Piccirillo, L., Pisano, G., Taylor, A. C., Withington, S.Contributors: “...Gear, W. K....”
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42by Church, S., Ade, P.A.R., Bock, J.J., Bowden, M., Carlstrom, J.E., Ganga, K., Gear, W.K., Hinderks, J., Hu, W., Keating, B.G., Kovac, J., Lange, A.E., Leitch, E., Mallie, O.E., Melhuish, S.J., Murphy, J.Anthony, Rusholme, B., O'Sullivan, Créidhe, Piccirillo, L., Pryke, C., Taylor, A., Thompson, K.Get access
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43by Maffei, B., Ade, Peter A. R., Calderon, C., Challinor, A. D., De Bernardis, P., Dunlop, L., Gear, Walter Kieran, Giraud-Héraud, Y., Goldie, D. J., Grainge, K. J.B., Isaak, K. G., Johnson, B., Jones, M. E., Lasenby, A. N., Mauskopf, Philip Daniel, Melhuish, S. J., Orlando, A., Piccirillo, L., Pisano, G., Taylor, A., Withington, S., Yassin, G.Get access
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44by Maffei, B., Ade, P.A.R., Calderon, C., Challinor, A.D., De Bernardis, P., Dunlop, L., Gear, W.K., Giraud-Héraud, Y., Goldie, D.J., Grainge, K.J.B., Isaak, K.G., Johnson, B., Jones, M.E., Lasenby, A.N., Mauskopf, P.D., Melhuish, S.J., Orlando, A., Piccirillo, L., Pisano, G., Taylor, A.C., Withington, S., Yassin, G.Get access
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45by Maffei, B., Ade, P.A.R., Calderon, C., Challinor, A.D., de Bernardis, P., Dunlop, L., Gear, W.K., Giraud-Héraud, Y., Goldie, D.J., Grainge, K.J.B., Isaak, K.G., Johnson, B., Jones, M.E., Lasenby, A.N., Mauskopf, P.D., Melhuish, S.J., Orlando, A., Piccirillo, L., Pisano, G., Taylor, A.C., Withington, S., Yassin, G.Get access
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46by Maffei, B., Ade, P.A.R., Calderon, C., Challinor, A.D., de Bernardis, P., Dunlop, L., Gear, W.K., Giraud-Héraud, Y., Goldie, D.J., Grainge, K.J.B., Isaak, K.G., Johnson, B., Jones, M.E., Lasenby, A.N., Mauskopf, P.D., Melhuish, S.J., Orlando, A., Piccirillo, L., Pisano, G., Taylor, A.C., Withington, S., Yassin, G.Get access
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47by Maffei B., Ade P. A. R., Calderon C., Challinor A. D., De Bernardis P., Dunlop L., Gear W. K., Giraud-Heraud Y., Goldie D. J., Grainge K. J. B., Isaak K. G., Johnson B., Jones M. E., Lasenby A. N., Mauskopf P. D., Melhuish S. J., Orlando A., Piccirillo L., Pisano G., Taylor A. C., Withington S., Yassin G.Contributors: “...Gear, W. K....”
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48by Maffei, B., Ade, P.A.R., Calderon, C., Challinor, A.D., de Bernardis, P., Dunlop, L., Gear, W.K., Giraud-Héraud, Y., Goldie, D.J., Grainge, K.J.B., Isaak, K.G., Johnson, B., Jones, M.E., Lasenby, A.N., Mauskopf, P.D., Melhuish, S.J., Orlando, A., Piccirillo, L., Pisano, G., Taylor, A.C., Withington, S., Yassin, G.Get access
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49by Maffei, B., Ade, P.A.R., Calderon, C., Challinor, A.D., de Bernardis, P., Dunlop, L., Gear, W.K., Giraud-Héraud, Y., Goldie, D.J., Grainge, K.J.B., Isaak, K.G., Johnson, B., Jones, M.E., Lasenby, A.N., Mauskopf, P.D., Melhuish, S.J., Orlando, A., Piccirillo, L., Pisano, G., Taylor, A.C., Withington, S., Yassin, G.Get access
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50by Maffei, B., Ade, P.A.R., Calderon, C., Challinor, A.D., de Bernardis, P., Dunlop, L., Gear, W.K., Giraud-Héraud, Y., Goldie, D.J., Grainge, K.J.B., Isaak, K.G., Johnson, B., Jones, M.E., Lasenby, A.N., Mauskopf, P.D., Melhuish, S.J., Orlando, A., Piccirillo, L., Pisano, G., Taylor, A.C., Withington, S., Yassin, G.Get access
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51by Maffei, B., Ade, P. A R, Calderon, C., Challinor, A. D., De Bernardis, P., Dunlop, L., Gear, W. K., Giraud-Héraud, Y., Goldie, D. J., Grainge, K. J B, Isaak, K. G., Johnson, B., Jones, M. E., Lasenby, A. N., Mauskopf, P. D., Melhuish, S. J., Orlando, A., Piccirillo, L., Pisano, G., Taylor, A. C., Withington, S., Yassin, G.Get access
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52by Chris B Thaxter, Ross-Smith, Viola H, Clark, Jacquie A, Nigel A, Conway, Greg J, Masden, Elizabeth, Wade, Helen M, Leat, Eliza H K, Gear, Sheila C, Marsh, Mike, Booth, Chris, Furness, Robert W, Votier, Steve C, Burton, Niall H K, C B Thaxter, V H, J A Clark, N A Conway, Masden, E., . G J Burton, N H KGet access
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53by Bowden, M, Taylor, A N, Ganga, K, Ade, P A R, Bock, J J, Cahill, G, Carlstrom, J E, Church, S E, Gear, W K, Hinderks, J R, Hu, W, Keating, B G, Kovács, J, Lange, A E, Leitch, E M, Mallie, O E, Melhuish, S J, Murphy, J A, Piccirillo, L, Pryke, C L, Rusholme, B A, O'Sullivan, C, Thompson, KGet access
Published 2003
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54by Bowden, M., Taylor, A. N., Ganga, K. M., Ade, P. A. R., Bock, J. J., Cahill, G., Carlstrom, J. E., Church, S. E., Gear, W. K., Hinderks, J. R., Hu, W., Keating, B. G., Kovac, J., Lange, A . E., Leitch, E. M., Mallie, O. E., Melhuish, S. J., Murphy, J. A., Piccirillo, L., Pryke, C., Rusholme, B. A., O'Sullivan, C., Thompson, K.Get access
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55by Bowden, M., Taylor, A.N., Ganga, K., Ade, P.A.R., Bock, J.J., Cahill, G., Carlstrom, J.E., Church, S., Gear, W.K., Hinderks, J.R., Hu, W., Keating, B.G., Kovac, J., Lange, A.E., Leitch, E.M., Maffei, B., Mallie, O.E., Melhuish, S.J., Murphy, J.Anthony, Pisano, G., Piccirillo, L., Pryke, C., Rusholme, B., O'Sullivan, Créidhe, Thompson, K.Get access
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56by Bowden, M., Taylor, A. N., Ganga, K. M., Ade, P. A. R., Bock, J. J., Cahill, G., Carlstrom, J. E., Church, S. E., Gear, W. K., Hinderks, J. R., Hu, W., Keating, B. G., Kovac, J., Lange, A . E., Leitch, E. M., Mallie, O. E., Melhuish, S. J., Murphy, J. A., Piccirillo, L., Pryke, C., Rusholme, B. A., O'Sullivan, C., Thompson, K.Get access
Published in Monthly Notices of the Royal Astronomical Society (2003)
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57by Ade, P., Bock, J., Bowden, M., Brown, M. L., Cahill, G., Carlstrom, J. E., Castro, P. G., Church, S., Culverhouse, T., Friedman, R., Ganga, K., Gear, W. K., Hinderks, J., Kovac, J., Lange, A. E., Leitch, E., Melhuish, S. J., Murphy, J. A., Orlando, A., Schwarz, R., O'Sullivan, C., Piccirillo, L., Pryke, C., Rajguru, N., Rusholme, B., Taylor, A. N., Thompson, K. L., Wu, E. Y. S., Zemcov, M.Get access
Published in The Astrophysical Journal (2008)
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58by Ade, P., Bock, J., Bowden, M., Brown, M. L., Cahill, G., Carlstrom, J. E., Castro, P. G., Church, S., Culverhouse, T., Friedman, R., Ganga, K., Gear, W. K., Hinderks, J., Kovac, J., Lange, A. E., Leitch, E., Melhuish, S. J., Murphy, J. A., Orlando, A., Schwarz, R., O'Sullivan, C., Piccirillo, L., Pryke, C., Rajguru, N., Rusholme, B., Taylor, A. N., Thompson, K. L., Wu, E. Y. S., Zemcov, M.Get access
Published in The Astrophysical Journal (2008)
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59by Ade, P., Bock, J., Bowden, M., Brown, M. L., Cahill, V., Carlstrom, J. E., Castro, P. G., Church, S., Culverhouse, T., Friedman, R., Ganga, K., Gear, W. K., Hinderks, J., Kovac, J., Lange, A. E., Leitch, E. M., Melhuish, S. J., Murphy, J. A., Orlando, A., Schwarz, R., O'Sullivan, C., Piccirillo, L., Pryke, C., Rajguru, N., Rusholme, B., Taylor, A. N., Thompson, K. L., Wu, E. Y. S., Zemcov, M.Get access
Published in The Astrophysical Journal (2008)
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60by Ade, P., Bock, J., Bowden, M., Brown, M. L., Cahill, G., Carlstrom, J. E., Castro, P. G., Church, S., Culverhouse, T., Friedman, R., Ganga, K., Gear, W. K., Hinderks, J., Kovac, John M, Lange, A. E., Leitch, E., Melhuish, S. J., Murphy, J. A., Orlando, A., Schwarz, R., O’Sullivan, C., Piccirillo, L., Pryke, C., Rajguru, N., Rusholme, B., Taylor, A. N., Thompson, K. L., Wu, E. Y. S., Zemcov, M.Get access
Published in The Astrophysical Journal (2008)
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