Double helical gear provide enough relief copy. between two identical helicial gears having opposite hand of helix. it is easy to fabricate and cheaper.
but in case of herringbone gear, no such gap . thus two identical helical gears with opposite hand of helix touched each other. although both gears used interchangeably, they are not exactly same. so let’s look into the basic differences between double helical gear and herringbone gear.
What is herringbone gear?
Herringbone gears are a combination of double helical gears. with the two helicals arranged on opposite sides of the hand. The teeth of a herringbone gear arranged at an angle with the helix angle. with no gap between the right and left helix. and appear in the shape of the letter “V.”
What are the advantages of herringbone gears ？
Since this structure has more than two teeth meshing with each other . at the same time, this has the advantage of smooth power transmission. The angled teeth of the herringbone gear help generate axial force and heat. which is proportional to the size of the tangent of the helix.
The angle of the helix to the axis of rotation is 45 degrees. but a larger helix angle provides higher speeds. The setting of the two teeth of the herringbone gear counteracts the thrust forces exerted on each other. providing the advantage of smooth operation even at higher speeds.
Herringbone gears are more expensive compared to other gears . due to their special construction, which makes them difficult to manufacture. and the arrangement of the teeth increases manufacturing costs. It helps provide smoother and quieter operation and offer high speeds.
What is a double helical gear?
A double helical gear combines two oppositely oriented helical gears of the same helix angle. so that the opposing thrust forces cancel each other out. To overcome axial thrust, double helical gears sometimes counteract or nullify the forces. The entire face divided into two equal halves with the same helix angle but opposite hands. The axial thrusts opposed. and the forces contained in the gear rather than transmitted to the bearing.
What are the advantages double helical gears ？
Double helical gears have a large number of teeth which helps in the reduction of heat build-up. hence they can last longer. Double helical gears have fewer parts in comparison to worms gearbox. And better at cutting curves compared to spur gears.
It as using two spiral-shaped surfaces on a single gear. which makes them stronger than the normal ones. And simple and easy to use, making them an economical choice for most applications.
More efficient because of the way they transfer power between the input and output shafts. and It provides a significant amount of power to the output shaft. with less mechanical energy required at the input.
The Difference Between Double Helical Gears and Herringbone Gears
In helical gears the tooth shape cut at an angle to the gear axis in a helical form on a cylindrical gear blank. It reduces wear, vibration and noise by gradually fitting instead of abruptly meshing and disengaging the teeth.
However, there is a difference between herringbone gear and double helical gear. It has a pair of paired helical gears that generate axial thrust. that is eventually transferred to the bearings.
Which requires large and expensive bearings. To eliminate this thrust on the bearings. Same-axis helical gears. One has a left-helix and the other a right-helix.When connecting two helical gears, a small clearance sometimes maintained between them. The main basis is the presence or absence of this intermediate clearance.
Although double helical gears and herringbone gears are often used interchangeably. they are not identical.Difference Between Herringbone Gear and Double Helical Gear.
However, they serve the same purpose and provide similar benefits compared to single helical gears. In the case of double helical gears. There is sufficient backlash clearance , between two identical helical gears with opposite helical hands.
In the case of herringbone gears, no such clearance is provided. Therefore, the two identical helical gears have opposite helical hands . that physically contact each other.Possible overlap complicates their production. Cutting gear teeth requires specialized equipment.
Single helical gears provided axial force in both cases. It’s backwards. As a result, the synthetic thrust becomes zero.
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