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Power Transmission, Brakes and Cooling Systems
Published in Iqbal Husain, Electric and Hybrid Vehicles, 2021
The four principle types of gears are: spur, helical, bevel and worm gears. Almost all types of gears can be found in an automobile. Spur gears are the simplest of all types whose teeth connect in parallel to the axis of rotation. Power is transmitted to parallel shafts connected by the spur gear. Helical gears have teeth inclined to the axis of rotation, but transmit power between parallel shafts just like the spur gear. Bevel gears transmit power between shafts that intersect, but are not in parallel. The differential of an automobile uses bevel gears. Hypoid gears are a type of bevel gear whose teeth form circular arc and the shafts are nonintersecting. These gears connect shafts that are neither parallel, nor do they intersect such as in the final drive of the power train. The gear schematic in Figure 14.3 represents either a spur gear or a helical gear. This representation is used below to develop the gear input-output relationships.
Design and Kinematic Analysis of Gears
Published in Kevin Russell, Qiong Shen, Raj S. Sodhi, Kinematics and Dynamics of Mechanical Systems Implementation in MATLAB® and Simmechanics®, 2018
Kevin Russell, Qiong Shen, Raj S. Sodhi
The shaft angle is the sum of the pinion-pitch angle and the gear-pitch angle (Figure 8.25). The pitch angle is the angle of the cone upon which the bevel gear is constructed. The gear- and pinion-pitch angles are represented by the variables γpinion and γgear, respectively. The equations for γpinion and γgear can be expressed as tanγpinion=sin∑cos∑+NgearNpiniontanγgear=sin∑cos∑+NpinionNgear
Application Topics
Published in Q. Jane Wang, Dong Zhu, Interfacial Mechanics, 2019
Spiral bevel and hypoid gears are key components widely used for transmitting significant power and motion in various vehicles and engineering machineries. In comparison with straight bevel gears, they can better handle heavier torque loads at higher operating speeds. In engineering applications, operation of hypoid gears is usually smoother and quieter than that of straight and spiral bevel gears. However, as in all gear sets with nonparallel nonintersecting axes, high sliding usually takes place across the tooth flanks in hypoid gears. Therefore, hypoid gears often encounter various problems, such as low efficiency, possible high operating temperature, high churning loss, and excessive sliding wear.
A Mixed TEHL Model for the Prediction of Thermal Effect on Lubrication Performance in Spiral Bevel Gears
Published in Tribology Transactions, 2020
Daofei Wang, Si Ren, Ying Zhang, Wei Pu
Spiral bevel gears have many advantages, such as transmission stability, large carrying capacity, and space transmission capacity. They are widely used in heavy-duty trucks, construction machinery, and aircraft engines. The characteristics of the velocity vector on the meshing tooth surface in spiral bevel gears are very different from those of ordinary cylindrical gears and bearings. The velocity vectors of two surfaces commonly do not coincide with the main axes of the Hertzian contact zone, which may lead to high sliding speeds. Scuffing is a major failure mode for spiral bevel gears subjected to severe heat generation, in addition to ordinary failure forms like contact fatigue and wear. Therefore, it is of significant importance to study thermal effects on the lubrication performance and film breakdown in spiral bevel gears.
Effects of modification on the strength–weight ratio of standard bevel gears
Published in Mechanics Based Design of Structures and Machines, 2022
Several types of gears, such as bevel, noncircular, oblique, helical, spur, and hypoid gears, are used in motion transmission. Production and calculation standards have been developed for gears similar to those developed for other machine elements. Bevel gears are used in automotive, aerospace, construction, and other industries to transmit momentum through shafts positioned perpendicular to each other and have a changing module (Yang et al. 2010). Bevel gears are defined by an outer transverse and a normal module. They are preferred in systems wherein the rolling linear velocity does not exceed 5 m/s and the noise does not cause many problems. Contact rates are highly affected by production tolerance and assembly error. Therefore, bevel gears must be produced as a set. This is particularly important in vehicle differential gears (Ni et al. 2018; Childs 2014). Unlike majority of the other standardized machine elements, the purpose of modifications is to develop the standardized forms of gears. Modifications are performed to increase the strength–weight ratio, create high reliability, compact systems, and eliminate noise as well as vibration (Z. Wei 2004). Effective modifications require fast, efficient, and correct calculations. The modification process requires experimental tests and the prototypes are markedly expensive; hence, computer-aided design tools are required for these modifications (Wen, Du, and Zhai 2020; Mohammed et al. 2018). Repetitive contact pressure and tooth root bending stress occur in gear pairs during motion transmission (Karaveer et al. 2013). This pattern of repeated loading often causes cracks in the tooth root and pitting failure on the tooth surface (Maršálek and Moravec 2011; A. K. Singh and Dewangan 2015; Silori et al. 2015).
Tooth contact analysis of straight bevel gears in the function of the modification of number of teeth of the driving gear
Published in Australian Journal of Mechanical Engineering, 2022
Straight bevel gears are applied widely in machinery (in vehicles, tool machines, robots, for medical tools, etc.). They are used to connect shafts whose axes intersect in some angle; thus, the meshing surfaces form a cone on which teeth are shaped (Figures 1 & 2) (Argyris, Fuentes, and Litvin 2002; Dudás 2011; Dudás 1991; Erney 1983; Fuentes and Iserte 2011; Goldfarb, Trubachev, and Barmina 2018; Litvin and Fuentes 2004; Litvin 1972; Rohonyi 1980; Terplán 1975).