Types of Bevel Gears : Many mechanical systems have bevel gears, which are essential for transferring force and motion between intersecting shafts. These gears are appropriate for applications that require changes in direction, speed, or torque since they are made expressly to operate at angles other than parallel or perpendicular. In this article, we’ll look at the several types of bevel gears with uses, applications.
What is a Bevel Gear ?
Bevel Gears are a types of Gears which is used for transferring mechanical energy or shaft power which axes of the two shafts intersect and the tooth-bearing faces of the gears themselves are conically shaped.
It is cone-shaped gears that transmit motion between two intersecting axes. They are typically installed on shafts 90 degrees apart, but can be configured for almost any angle.
Bevel gears have two main shafts that cross with splines modelled as cones. These bevel gears are commonly used on shafts and are 90 degrees apart. The geometry of the overall design determines the classification of bevel gears. But first, let’s define a bevel gear.
These types of gears are often installed on shafts that are 90 degrees apart, although they can also be engineered to work at different angles. The pitch surface of bevel gears is a cone, which is referred to as a pitch cone. Bevel gears convert energy from linear to vertical power, making them extremely helpful in mechanical machinery.
Let is understand different types of Bevel gears with Image.
Types of Bevel Gear ?
Types of Bevel gears according to their geometry;
- Straight Gears
- Spiral bevel gears
- Zerol Gears
- Hypoid Gears
- Mitre Gears
# Straight Bevel Gears
Straight bevel gears are both the most basic and the most common type of bevel gear. True to their name, they resemble a spur gear and feature straight teeth, however they are conical rather than cylindrical.
Due to the same tooth form and the manner their teeth engage, they also have several characteristics in common with spur gears. A straight bevel gear has a conical pitch surface with teeth that are straight and taper to the apex.
Note : Teeth of this type of gears are straight and are cut along the axis on a cone.
# Spiral Bevel Gears
Spiral bevel gears are types of bevel gears which have curved teeth at a particular angle, causing tooth contact to be smooth and gradual.
Spiral Bevel gears are complex form of bevel gear. Spiral gear teeth are curved and oblique, as opposed to straight bevel gear teeth. This causes increased tooth overlap, promoting progressive engagement and disengagement upon tooth contact.
Because of the improved smoothness, there is less vibration and noise generated during operation. Spiral bevel gears also have higher load capabilities due to higher load sharing from more teeth in contact. Because of this, they can be smaller than straight bevel gears of the same capacity.
A spiral bevel gear is a bevel gear with helical teeth. This primarily applies in differentials for vehicles, where driving the wheels requires a 90-degree change in the drive direction from the drive shaft. Compared to typical straight-cut or spur-cut gear with straight teeth, the helical shape makes less vibration and noise.
This gear always be replaced in pairs i.e. both the left hand and right hand gears should be replaced together since the gears are manufactured and lapped in pairs.
# Zerol Bevel Gears
Zerol bevel gears are spiral bevel gears with a zero spiral angle in the centre of the face width. This is combination of advantages of straight and spiral bevel gears.
These bevel gears are a form of bevel gear that falls somewhere between straight and spiral bevel gears. Their teeth are slightly bent but not angled. These bevel gears are meant to mimic the characteristics of a straight bevel gear, but they are manufactured using a spiral bevel cutting method.
# hypoid Bevel gear
Hypoid bevel gears are types of bevel gears which are similar to spiral bevel gears, except the pitch surfaces are not conical and hyperbolic. The pinion can be positioned below or above the gear centre, allowing for larger pinion diameter, smoother mesh, and longer life. If the bevelled plate is built parallel to the rotating axis, the configuration resembles a worm drive. Hypoid gears were widely used in automotive rear axles.
It is a form of bevel gear in which the shaft axes are neither intersecting nor parallel. The offset is the distance between the two gear axes. Hypoid bevel gears have helical teeth, comparable to spiral bevel gears. A hypoid bevel gear with no offset is nothing more than a spiral bevel gear. The fabrication and shaping of hypoid gears is comparable to those of spiral bevel gears.
# Mitre Gears
Mitre gears are a types of bevel gears with an equal number of teeth. The shafts are at right angles, and the gears have matching pitch surfaces and angles, with a conically-shaped pitch surface.
Mitre gears are bevel gears that have a gear ratio of 1:1 when paired. This gear ratio results from the combination of two mitre gears with the same number of teeth. This type of bevel gear is employed in applications that simply require a change in the axis of rotation while keeping the speed constant.
The Geometry of Different Types of Bevel Gears
Citroen built a double-helical type of bevel gear for the Miejovice water power plant in 1927. The cylindrical gear tooth profile is a twisted form (i.e., a triangle wave installed on the circumference of a circle), whereas the bevel gear tooth profile is an octoid (i.e., a triangle wave put on the standard path of a sphere’s edge).
All conventional bevel gear manufacturers (including Heidenreich & Harbeck, Gleason, WMW Modul, and Klingelnberg) produce bevel gears with an alternative tooth form. It is critical to remember that for 5-axis assembled bevel gear sets, the same calculation/layout, including the standard production procedure, must be used.
Simplified showed bevel gears based on an analogous cylindrical gear in a standard section with an involute tooth form show a deviant tooth shape with lowered tooth strength by 45% with offset and 10-28% without offset. Furthermore, those “involute bevel gear configurations” produce greater noise.
Applications of Different types of Bevel Gears
Bevel gear is used in a wide range of applications, including locomotives, maritime applications, vehicles, printing presses, cooling towers, power plants, steel factories, railway track inspection devices, and so on.
- Bevel gears are used in differential drives, which can deliver energy to two axles rotating at different speeds, like as those on a cornering car.
- A hand drill’s basic function is to use bevel gears. When the drill handle is rotated vertically, the bevel gears convert the spinning of the chuck to a horizontal motion. The bevel gears in this system have the added benefit of increasing the rotation velocity of the chuck, making it possible to drill a variety of materials.
- A bevel gear planer’s gears allow for modest adjustment during construction and allow for some displacement based on deflection under operating powers without concentrating force on the end part of the tooth.
- Spiral bevel gears are critical components of rotorcraft driving systems. These components are required to perform under high loads, high speeds, and several load cycles. In this scenario, spiral bevel gears are used to convert a gas turbine shaft from horizontal to vertical output. Bevel gears are also used to lower velocity.
Advantages
- This gear allows you to adjust the operating angle.
- The number of teeth (effectively diameter) on each wheel can be varied to modify mechanical advantage. The ratio of teeth between the drive and driven wheels can be changed by increasing or decreasing the ratio of rotations between the two, which means that the rotational drive and torque of the second wheel can be changed in relation to the first, with speed increasing and torque decreasing, or speed decreasing and torque increasing.
Disadvantages of different types of bevel gears
- One wheel of such gear is meant to work only with its corresponding wheel.
- Mounting must be done exactly.
- The bearings on the shafts must be able to withstand high forces.
Conclusion for Different Types of Bevel Gears
In This article I have mention different types of bevel gears with image and their functions in details. If you have any doubt, don’t forget to comment.
Refrence: wikipedia
