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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.
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
As mentioned in Section 8.2, helical gears can be used to transmit motion between parallel and nonparallel shafts (also called crossed shafts) that do not intersect.* It was also noted in that section that helical gears have a greater load-bearing capacity and wear resistance, quieter and smoother operation than spur gears. These advantages are the result of the teeth of a helical gear lying at an angle (labeled the helix angle in Figure 8.15) with respect to the gear’s center axis. This angled tooth profile increases the contact between mating gear teeth for greater load distribution (resulting in the advantages given).†
Gears and Gear Trains
Published in Eric Constans, Karl B. Dyer, Introduction to Mechanism Design, 2018
Like spur gears, helical gears can transmit motion between parallel axes. The teeth of a helical gear are set at an angle, called the helix angle. A common value for the helix angle is 45° as shown in Figure 8.2. Because of the helix angle, the teeth engage gradually (and therefore quietly) instead of suddenly, as in the case of spur gears. All forward gears in a manual transmission are helical, which is the main reason that manual transmissions are almost inaudible at highway speeds. Helical gears have more teeth in contact than spur gears; this distributes the load more evenly and makes helical gears, on average, stronger than spur gears.
Numerical Modeling of Churning Power Loss of Gear System Based on Moving Particle Method
Published in Tribology Transactions, 2020
Dong Guo, Fangchao Chen, Jiao Liu, Yawen Wang, Xi Wang
In this article, the influence of gear geometry parameters and operating conditions on gear pair churning losses was studied by orthogonal simulation analysis. The primary factor influencing the churning losses was rotation speed, and the churning losses increased with increasing rotation speed. The churning losses increased as the depth of oil immersion increased due to the collision and friction of the gear pair with the oil, resulting in greater power loss. The churning losses decreased as the oil temperature increased due to the effect of viscosity and density of the oil on the churning losses. The factors affecting the gear pair parameters were tooth width and helix angle. An increase in the helix angle caused the linear velocity of the gear to increase.
Dynamic characteristic prediction of multistage gear-cylinder transmission system
Published in Journal of the Chinese Institute of Engineers, 2019
Yu-Jiang Wang, Tian-Cheng Ouyang, Ming-Zhang Pan, Hui Chen
As a matter of fact, the larger the helix angle is, the longer the meshing line; therefore, the gear transmission is more smooth. Nevertheless, a larger helix angle would lead to an excessive axial force. It can be seen in Figure 11(a)that the meshing stiffness decreases with the increase in pressure angle similar to that seen in Figure 10(a), but the variation is not obvious. The variation of natural frequency with helix angle is described in Figure 11(b), but the changes in the first three orders of natural frequencies are extremely small.
Enhancement of surface temperature distribution of solar receiver tube using coil winding
Published in International Journal of Ambient Energy, 2020
The helix angle is defined as the angle between any helix and an axial line on its right, circular cylinder or cone. In this paper, the helix angle is 82°. The pitch of a helical coil is defined as the distance from centre to centre of two adjacent coils. The pitch for this case is calculated as 68.5 mm. Here, from the equation of total length of wounded coil it is found to be 6.2 m. The properly designed helical coil used for wounding the straight solar receiver tube in this experiment is shown in Figure 1.