Helical Gear

What is a Helical Gear?

Helical gears are the mechanical components that transmit motion and power between two parallel shafts. They are called helical gears because the teeth on the gear are inclined at an angle to the face of the gear rather than being perpendicular to it. This design allows the gears to mesh smoothly and quietly, making them ideal for many applications.

Helical gears are grouped into two classes based on whether the reference section of the gears is in the rotating plane (transverse module) or the normal plane (normal module). If the reference section is in the rotational plane, the center distance is similar to spur gears as long as the module and number of teeth are the same. This enables simple spur gear switching. However, they necessitate specialized hobbing cutters and grinding stones in this situation, resulting in greater production costs.

Helical Gear Diagram

The diagram of the left-hand helical gear and right-hand helical gear is shown below:

Specifications of Helical Gears

Helical gears are mechanical components with various specifications that determine their size, shape, and performance characteristics. Some of the main specifications of helical gears include the following:

• Pitch: The pitch of a helical gear refers to the distance between the teeth on the gear. The pitch is usually measured in millimeters or inches, which determines the size and spacing of the teeth on the gear.

• Diameter: The diameter of a helical gear is the distance across the gear from one edge of the teeth to the opposite edge. The diameter is typically measured in millimeters or inches, determining the gear’s overall size.

• The number of teeth: The number of teeth on a helical gear determines the number of points of contact between the gear and the teeth of the mating gear. A larger number of teeth can provide more contact points and a smoother, more efficient operation.

• Helix angle: The helix angle of a helical gear is the angle at which the teeth are inclined relative to the face of the gear. The helix angle can vary but is typically between 15 and 45 degrees.

• Material: Helical gears are typically made from metal, such as steel or aluminum, but can also be made from other materials, such as plastic or composite materials. The choice of material can affect the gears’ strength, durability, and cost.

Overall, the specifications of a helical gear determine its size, shape, and performance characteristics and can vary depending on the application and operating conditions.

Types of Helical Gears

There are several different types of helical gears, which can be distinguished based on the angle of the teeth, the direction of the helix, and the arrangement of the gears. Some common types of helical gears include:

1. Single helical gears: Single helical gears have teeth inclined at an angle to the face of the gear. The angle of the teeth can vary but is typically between 15 and 45 degrees. Single helical gears can be used in pairs, with one gear meshing with the other, to transmit motion and power between parallel shafts.

2. Double helical gears: Double helical gears, also known as herringbone gears, have teeth inclined in opposite directions on opposite sides of the gear. This allows the gears to mesh smoothly and quietly, reducing the axial thrust forces generated by single helical gears.

3. Spiral bevel gears are helical gears that transmit motion and power between non-parallel shafts. The teeth on spiral bevel gears are inclined at an angle to the face of the gear, and the gears are arranged at an angle to each other. This allows them to transmit motion and power at an angle, making them suitable for applications where the shafts are not aligned.

4. Hypoid gears: Hypoid gears are spiral bevel gears with teeth that are offset from the center of the gear. This allows the gears to have a higher gear ratio and a larger contact area between the teeth, which increases their load-carrying capacity and efficiency. Hypoid gears are often used in automotive transmissions.

Overall, there are several different types of helical gears, each suited for different applications and operating conditions.

Helical Gearbox Working Principle

Helical gears are becoming more popular as power transmission gears since they can sustain bigger loads due to their reduced dynamic load and lower noise and vibration levels than spur gears. A helical gearbox includes a set of helical gears. Helical gears are a type of cylindrical gear having a slanted tooth trace. They have a greater contact level, less vibration, are quieter, and can transfer bigger loads than spur gears. The helix angle of a pair of helical gears is the same, but the helix hand is on the other side. 

When the reference component of the gear is in standard form, the spur gear hobbing tool and hobbing machine can manufacture helical gears by tilting the hobbing instrument. Because of the teeth twist, their creation has the drawback of more difficult construction.

Application of Helical Gears

Helical gears are mechanical components that transmit motion and power between two parallel shafts. They are called helical gears because the teeth on the gear are inclined at an angle to the face of the gear rather than being perpendicular to it. This design allows the gears to mesh smoothly and quietly, making them ideal for many applications.

Some common applications for helical gears include:

• Automotive transmissions: Helical gears are often used in automotive transmissions to transmit power from the engine to the drive wheels.
• Industrial machinery: Helical gears are commonly used in industrial machinery, such as conveyor belts, mixers, and pumps, to transmit motion and power between different machine components.
• Aerospace: Helical gears are used in many aerospace applications, such as aircraft landing gear and satellite control systems.
• Robotics: Helical gears are often used in robotics applications to provide precise, smooth motion and power transmission between different robot parts.

Helical gears are versatile components widely used in many applications where smooth, quiet motion and power transmission are important.

Advantages of Helical Gears

Helical gears have several advantages over other types of gears, including:

• Smooth and quiet operation: Because the teeth on helical gears are inclined at an angle to the face of the gear, they mesh smoothly and quietly, which makes them ideal for use in applications where noise reduction is important.

• High load capacity: Helical gears have a high load capacity, which means they can transmit high amounts of torque and power without failing. This makes them suitable for use in applications where high loads are present.

• Higher efficiency: Helical gears are more efficient than other gears, such as spur gears, because the inclined teeth allow for a more gradual transfer of power from one gear to the other. This reduces the amount of power lost as heat and increases the system’s overall efficiency.

• Versatility: Helical gears can be used in various applications, from automotive transmissions to industrial machinery and robotics. This versatility makes them a popular choice for many different types of applications.

Overall, the smooth and quiet operation, high load capacity, high efficiency, and versatility of helical gears make them a popular choice for many applications.

Disadvantages of Helical Gears

While helical gears have many advantages, they also have disadvantages compared to other gears. Some of the main disadvantages of helical gears include the following:

• More complex manufacturing process: The inclined teeth on helical gears make them more difficult to manufacture than other gears, such as spur gears. This complexity can make them more expensive to produce and sometimes limit availability.

• Limited sizes: Because of the complex manufacturing process, helical gears are typically only available in a limited range of sizes. This can make it difficult to find the right size gear for a specific application.

• The limited angle of contact: The angle of contact between the teeth on helical gears is limited, which can reduce their load-carrying capacity compared to other types of gears.

• High axial thrust: The inclined teeth on helical gears can generate a high axial thrust force, which the bearings and other components in the system must accommodate. This can make it necessary to use special bearings or other components to support the gears, which can add to the cost and complexity of the system.

While helical gears have many advantages, their complex manufacturing process, limited range of sizes, angle of contact, and high axial thrust can make them less suitable for some applications compared to other types of gears.

Important GATE Notes
Steel	Zero Force Member In A Truss
Difference between Machine and Mechanism	Transverse Loading
Geometric Design Of Highways	Void Pointers in C
Macaulay’s Method	Impact Load
Impulse An Momentum	Uniformly Varying Load