A helical is a spur gear with an angle along the face to increase the gear contact ratio. The gear teeth are cut at angles
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the module of a helical gear is calculated in the same way of that of a spur gear: module=pitch diameter / no of teeth the module of a helical gear is calculated in the same way of that of a spur gear: module=pitch diameter / no of teeth
A bevel gear provides torque and rotation at 90 degrees, and a helical gear provides it at 180 degrees.
Double helical gear
Helical gears are similar to spur gear except it's teeth are slant. They have good load distribution, less noise and less wear compare to spur gear.
herring bone gear (Double helical ) doesn't axial thrust
Spur gears have straight teeth while helical gears have curved teeth. Generally, helical gears are usually quieter and smoother in operation, while spur gears are easier to make and much less expensive.Helical gears are stronger than spur gears.
The flow difference in gear compares because it spurs for 5 hours.
Planetary gears can be spur or helical gears.
A hobbing machine is used for cutting gear teeth in gear blanks and for cutting worm, spur, or helical gears.
External diameter / number of gear = pitch
herringbone gears are used when the speed requirement is even higher than that can be taken by the helical gears and they are even more noiseless and vibration free. This is because the bending moment that gets induced in the gear shaft of a helical gear is neutralised by another force acting against it in a herringbone gear.
It is called a gear tooth. There can be many types of teeth based on the gear design; such as spur, helical, straight bevel, spiral bevel, hypoid, and several others.