Gears are used in all types of machinery. They can be as small as 3mm diameter to 11m diameter. They are used to transmit rotary motion from one shaft to another by means of toothed wheels, which are in direct mesh with each other. In contrast, chain wheels transmit motion from one wheel to another by means of chain connection. They are called sprockets. Gears are used for power transmission as in automobile gearbox and in control elements.
Spur gears:
Spur gears are the most commonly used gears, are used to transmit motion between parallel shafts. These impose load on bearings. Its teeth are straight and parallel to the axis. These can be either internal type or external type. An external spur gear of infinite radius, called as rack. Rack has straight-sided tooth (for involute tooth profile gears).
Helical gears:
In helical gears, the tooth profile in transverse plane gets gradually rotated along the helix angle as we move along the axis. The hand of the helix determines whether it is a right handed helical gear or a left handed helical gear. Helical gears can be external or internal type. However, internal helical gears are not very common in external helical gears, the hands of the mating gears are of opposite hands, whereas for internal helical gear meshing with external gear, they are of the same hand. The mating gear should always have the same helix angle.
Sometimes double helical gears are also used where they have both right handed and left handed helical teeth on each gear. Normally there is a gap between the two helices. However, there are gears which have no gap between the helices double helical gear are also called chevron gears. Single helical gear impose both radial and thrust load on bearings. Double helical gear normally impose radial loads as the thrust loads due to opposite helices are in the opposite directions and, therefore, they cancel out. The spur gears can be considered as a special case of gears with helix angle equal to zero.
Spur gears:
Spur gears are the most commonly used gears, are used to transmit motion between parallel shafts. These impose load on bearings. Its teeth are straight and parallel to the axis. These can be either internal type or external type. An external spur gear of infinite radius, called as rack. Rack has straight-sided tooth (for involute tooth profile gears).
Helical gears:
In helical gears, the tooth profile in transverse plane gets gradually rotated along the helix angle as we move along the axis. The hand of the helix determines whether it is a right handed helical gear or a left handed helical gear. Helical gears can be external or internal type. However, internal helical gears are not very common in external helical gears, the hands of the mating gears are of opposite hands, whereas for internal helical gear meshing with external gear, they are of the same hand. The mating gear should always have the same helix angle.
Sometimes double helical gears are also used where they have both right handed and left handed helical teeth on each gear. Normally there is a gap between the two helices. However, there are gears which have no gap between the helices double helical gear are also called chevron gears. Single helical gear impose both radial and thrust load on bearings. Double helical gear normally impose radial loads as the thrust loads due to opposite helices are in the opposite directions and, therefore, they cancel out. The spur gears can be considered as a special case of gears with helix angle equal to zero.
4 comments:
Gear cutting tool design and production requires much specialized knowledge
i agree with dave that the designing and production of gear cutting tools require specialized knowledge...
we are the reputed Gear Cutters manufacturer in the market...
good explanation and We are specializing in the design and manufacturing of distinct categories of gears, these gears are manufactured with stringent quality norms followed globally. We are manufacturing Helical Gear, Spiral Bevel Gear, Bevel Gear, Worm Gear, and Spur Gear. For more information please visit http://www.globalautomotive-industry.com/products-services/gears/ms-pinak-industries-an-iso-9001-2008-company/?postTabs=0
Thanks for your blog spot, we learn about gear hobs which are used for power transmission as in auomobiles.
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