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Transmission
Published in Andrew Livesey, Practical Motorsport Engineering, 2019
Epicyclic gears are used in automatic gearboxes and Sturmey Archer bicycle hub gears. This is a type of gear arrangement where sun and planet gears run inside an annulus. This arrangement allows a range of ratios to be obtained from one gear set. In the diagram the inner gear is called the sun gear (1), the outer toothed part is the annulus gear (2), and the small gears between the sun gear and the annulus are called planet gears (3). Various ratios can be obtained from one set of epicyclic gears by locking each of the different sections in turn to the gearbox casing. For example, in an automatic gearbox the annulus can be held by a brake band so that the power is transmitted from the sun gear to the planet gears. In this case, the planet gears are turning, that is running around the inside of the annulus. If the carrier of the planet gears are held, the sun gear will rotate the planet gears on their spindles, which will turn the annulus. The latter gear ratio would be the lower.
Transmission System
Published in Andrew Livesey, Basic Motorsport Engineering, 2012
Epicyclic gears are used in automatic gearboxes and Sturmey Archer bicycle hub gears. This is a type of gear arrangement where sun and planet gears run inside an annulus. This arrangement allows a range of ratios to be obtained from one gear set. In Figure 8.17 the inner gear is called the sun gear (1), the outer toothed part is the annulus gear (2), and the small gears between the sun gear and the annulus are called planet gears (3). Various ratios can be obtained from one set of epicyclic gears, by locking each of the different sections in turn to the gearbox casing. For example, in an automatic gearbox the annulus can be held by a brake band so that the power is transmitted from the sun gear to the planet gears. In this case the planet gears are turning, that is running around the inside of the annulus. If the carrier of the planet gears is held, the sun gear will rotate the planet gears on their spindles, which will turn the annulus. The latter gear ratio would be the lower.
Industrial steam power in London, 1780–1805
Published in The International Journal for the History of Engineering & Technology, 2022
Everything changed for the future of steam power to industry in the years immediately after 1780, with the practicalisation of the application of both the Newcomen and Watt engines to rotary motion via the crank, or in Watt’s case the sun-and-planet gear he devised to avoid a patent (others simply ignored the patent, but Watt had good reason to avoid a court case).19 At first the application of rotary steam power was limited by the fact that the motion was not then sufficiently smooth for the two uses with the greatest potential, driving textile machinery and millstones in flour mills. It took some years of trial and error, plus technical development by both Boulton and Watt and other engine makers (who they often called ‘pirates’ as they sought to enforce their very restrictive patents and stifle competition), for many conservative mill owners to be won over, but by 1785 steam engines were being applied to drive directly grinding and turning machinery, as well as pumping water at industrial enterprises such as breweries. Often such engines were applied to both pumping and driving machinery at the same location.
Effects of tooth root cracks on vibration and dynamic transmission error responses of asymmetric gears: A comparative study
Published in Mechanics Based Design of Structures and Machines, 2023
Onur Can Kalay, Oğuz Doğan, Celalettin Yuce, Fatih Karpat
High load-carrying capacity and long fatigue life are demanded from modern transmission systems under harsh operating conditions. In this regard, tooth profile (i.e., asymmetry) and backup ratio stand out as two critical gear design parameters to achieve this end. The researchers have so far individually examined the influence of tooth asymmetry and backup ratio on the meshing stiffness and dynamic behavior (for example, vibration and TE). Besides, variations in gear dynamic response in the presence of major failure modes, such as wear and tooth root cracks, were investigated. For example, Liang, Zuo, and Pandey (2014) studied the dynamic behavior of a planetary gear set (sun or planet gear) in the presence of a tooth crack and then quantified TVMS reduction. As a result, it was concluded that TVMS reduced with an increment of the crack level. Meng, Shi, and Wang (2020) developed a 6-DOF dynamic model of a gear pair and calculated the meshing stiffness and dynamic displacement response in the presence of a tooth root crack. The researchers concluded that meshing stiffness reduced gradually with the increment of the crack length. It was also reported that the influence of tooth root cracks on the vibration signal became more pronounced as the crack length increased. Jiang and Liu (2020) evaluated the impact of tooth cracks on the helical gears’ meshing stiffness and DTE responses, considering three crack propagation scenarios. The research reported a decrease in the TVMS as the crack size propagated either in the directions of depth or length. Karpat, Yuce, and Doğan (2020) investigated the effects of drive-side pressure angle (tooth asymmetry) on the spur gears’ single-tooth stiffness and designed a special test rig to achieve this end. It was observed that the single-tooth stiffness could increase by approximately 38% as the drive-side pressure angle increases from 20° to 35°. In another example, Karpat et al. (2008) examined the influence of tooth asymmetry on the spur gear pairs’ dynamic characteristics (i.e., TVMS and static TE). Their study concluded that meshing stiffness could be improved by employing asymmetric profiled gears instead of standard designs. Doğan and Karpat (2019) developed a 4-DOF dynamic model and examined the influence of tooth asymmetry on the meshing stiffness and DTE responses of a cracked spur gear pair. To achieve this task, the researchers considered four different crack levels (20%-40%-60%-80%) and two drive-side pressure angles (αd = 20° and 35°). The findings of the research work revealed that as the crack level increased, TVMS decreased, and the impact of the fault on the DTE signal became more pronounced. As a supplementary finding, it was indicated that TVMS enhanced as the drive-side pressure angle increased. Recently, Mo et al. (2022) established an analytical model to evaluate the TVMS and TE of asymmetric gear pairs. The researchers validated their model by comparing its findings with those obtained through FEA simulations and further concluded that using an asymmetric tooth profile could increase the TVMS of a gear pair.