Helical Gears

Capabilities of Helical Gears

Helical gears are types of cylindrical gears that have a slanted teeth trace. They have a large contact ratio in comparison with spur gears and they are able to transmit greater force with less noise and vibration. One pair of helical gears possesses the same helix angle while the helix hand is opposite.

When the gear reference section is in normal plane, spur gear hobbing tool and machine could be used to manufacture helical gears with a slight tilt of the hobbing tool. The helical gear created by Vestavia can be grouped by the reference section of gears. Being in the transverse module or the rotating plane and the normal module or the normal plane. When the reference section is in rotating plane, the center distance is the same as in the case of spur gears as long as the module and the number of teeth are the same. This makes for easy substitution with spur gears. Spiral gears are used sometime in automotive transmissions after replacing the spur gears.

Characteristics of Helical Gears

Helical gears are also known as skew or dry fixed gears. They are set at an angle and as these gears are curved, angling makes their tooth shape into a helix segment. These gears can be meshed both in crossed and parallel orientations. With a parallel orientation, shafts are placed parallel to each other and this is a common kind of orientation. In the case of a crossed orientation, the shafts are non-parallel to each other and in this kind of a configuration, they function as skew gears.

Helical Gears have an edge over Spur Gears

The angled teeth of helical gears engage in a more gradual manner than those of the spur gears. They offer an advantage over spur gears as the leading edges of their teeth are not placed parallel to the rotational axis. This causes them to run in a smooth and a quiet manner. In the case of parallel helical gears, every teeth pair makes contact first at a single point at a side of the gear wheel. A moving contact curve then will grow slowly across the face of the tooth to a maximum. Before receding until the tooth breaks contact at one point on an opposite side. This offers an advantage over spur gears because in the case of the latter. The teeth will meet suddenly at a contact line across the whole width and this may lead to noise and stress. It has been observed that the spur gears make a typical whining sound at speeds that are high. For this particular reason, spur gears are mostly used in applications of low speed and in cases where noise control is not a big issue.

Advantage

A big advantage offered by spiral gears is through their torque capacity. By design, the spur gears are slightly weaker because their loads are transmitted over a set of fewer teeth. Helical gearing gets machined with teeth that are angled; they are then ground and hardened to obtain gear mesh of high efficiency. The gears will mesh gradually as the teeth are cut at angles. Teeth of every gear are in contact always with other gears, reducing the load on each tooth and creating smoother transition of forces from one tooth to another. This is the main reason why there is less wear, vibration and noise besides giving longer life.

Helical gears are always preferred in applications of high speed and in situations of large power transmission. They are also used in cases where noise abatement becomes an important factor. The problems created by helical gear come in the form of resultant thrusts along the gear axis that have to be accommodated by thrust bearings and a high degree of sliding friction between meshing teeth. This is taken care of by additives in the lubricants.

Types of Helical Gears

Helical gears are quite similar is use to spur gears when they are used on shafts which are parallel. When speeds exceed a thousand feet per minute, helical gears will always offer a smoother and a stronger running gear train. Stock gearing is usually furnished at a forty-five degree helix angle. The material types of helical gears that are made available. Steel, hardened steel, stainless steel, bronze, aluminum, phenol or non-metallic and nylon. The ground helical gears are superior in strength and they wear complete resistance, resulting in compact designs. The steel spiral gears have a larger contact ratio than their counterparts in spur gears. Resulting in effective reduction in both vibration and noise.

Capabilities of Helical Gears

Helical gears are types of cylindrical gears that have a slanted teeth trace. They have a large contact ratio in comparison with spur gears and they are able to transmit greater force with less noise and vibration. One pair of helical gears possesses the same helix angle while the helix hand is opposite.

Manufacturing Efficiency of Helical Gears

Helical gears can be described as parallel shaft gears for the purpose of manufacture and their mesh is in rolling contact almost in all cases. Resulting in higher efficiency that may range anywhere from 90.0% to 99.5%. These high-efficiency helical gears help in saving energy as they need less maintenance. And they last longer than spur and worm gears. Helical gears have helped many a manufacturer in going green. Various manufacturers who are replacing low-efficiency gear reducers with high-efficiency helical gears have ended up invariably with substantial savings.