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Example of Tribological Systems
Published in Kenneth C. Ludema, Oyelayo O. Ajayi, Friction, Wear, Lubrication, 2018
Kenneth C. Ludema, Oyelayo O. Ajayi
There are different types of gears depending on the location and orientation of the shafts, position and shape of the teeth. The following are examples of commonly used gears. Spur (straight) gear: This is the mostly used and analyzed type of gear. The teeth are straight and parallel to the axis of the shaft. Spur gears are used primarily to transmit power in gearbox.Helical gears: Are similar to spur gears but with teeth at some angle, called the helix angle, with respect to the shaft. Helical gears are often used instead of spur gears when quieter operation is needed. A helical gear can carry more load than a spur gear of the same size.Bevel gear: Are used to transmit power from one direction to another. For example, bevel gears are used to transmit power from an automotive engine at right angle to the wheels. Bevel gears often have spiral teeth, which are tapered in both thickness and height-spiral bevel gear. Sometimes the teeth are straight as in the straight bevel gears.Worm gear: The shaft is nonparallel and the worm which is more like a screw, drives the gear. The worm gears offer a large speed reduction with corresponding increase in torque. The teeth on worm gear can be angled or straight.
Application of an unstructured overset method for predicting the gear windage power losses
Published in Engineering Applications of Computational Fluid Mechanics, 2021
Y. Dai, L. Xu, X. Zhu, B. Ouyang
From a theoretical analytical point of view, Diab et al. (2004) employed a dimensionless and quasi-analysis approach, though the tip tangential speed was slower than 100 m/s, the theoretical data agreed well with the experimental values measured by spin-down tests. However, these derived formulas seem mostly to be valid for spur gears and Voeltzel et al. (2016) found that the helical angle and face width is influential to the generated windage losses in the case of helical gears. Soon after, another relevant work by Seetharaman and Kahraman (2009, 2010) also proposed a physics-based model to predict windage losses for a spur gear pair consisting of a pocketing power loss model of compressible fluid and a modification drag power losses model obtained from a previous churning losses model. However, the physics-based model developed by Seetharaman has a poor prediction of the windage power loss in terms of a single rotating spur/helical gear without considering the influence of the helical angle. Not only a spur or helical gear, but Wang et al. (2020) also established a power loss model for a high-speed heavy-load herringbone planetary transmission pair combining gear friction, windage behavior, and bearing friction. Zhu et al. (2020b) developed a quasi-analytical model to predict the windage power losses of an isolated spiral bevel gear. Furthermore, considering the windage behavior, Quiban et al. (2019) and Dai et al. (2020) respectively set up an analytical model to estimate the churning losses of a bevel gear. These models show higher accuracy in the air under the medium and low speed conditions.
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
Figure 1 shows a schematic diagram of a meshing pair in spiral bevel gears. The tooth surface of the spiral bevel gear is a complex surface. In the meshing transmission, the meshing area of the teeth is an ellipse instead of a circle or line. is the velocity vector of a pinion tooth, is the velocity vector of a gear tooth, and the angle between and is There is an angle between the entrainment speed and the minor axis of the contact ellipse and an angle between the sliding velocity and the minor axis.
An analysis model for predicting windage power loss of aviation spiral bevel gears under optimal injection jet layout
Published in Tribology Transactions, 2023
Linlin Li, Sanmin Wang, Linlin Liu
The boundary conditions arewhere, rz2 indicates the radius of element cylinder and is a function of local coordinate variable z2. According to the geometric relationship among the parameters of the gears on the back cone, as shown in Fig.16, there is: where, δB is the back cone angle of the spiral bevel gear.