Gearboxes with axes that are not parallel and do not intersect are known as hypoid gearboxes. Some types of spiral bevel gearboxes are hypoid gearboxes.
These types of gearboxes are used when the included angle is square and the axes are reasonably close together. The hypoid gear is thought to represent a middle ground between a worm gear machine and a bevel gear.
Well, in this reading, we’ll explore what a hypoid gearbox is, its applications, parts, diagram, and how it works. We’ll also explore its advantages and disadvantages.
Let’s begin!
What is Hypoid Gear?
Hypoid gearboxes are gearboxes having axes that are non-intersecting and not parallel. They are known to be a subcategory of spiral bevel gearboxes.
Similar to spiral bevel gearboxes, hypoid gearboxes vary in that their axes are not parallel and do not cross. Hypoid gears have axes that are offset from one another.
Instead of having the conical geometry of a spiral bevel gear, the hypoid gear’s fundamental geometry is hyperbolic.
The pinion diameter of a hypoid gearbox can be greater than that of a bevel gear pinion because the pinion’s spiral angle is greater than the gear’s spiral angle.
Because of the increased contact area and improved tooth strength, higher gear ratios (up to 200:1) may be employed, and more torque can be delivered. Bearings can be utilised on both sides of the gear to add extra stiffness because the shafts of hypoid gears do not cross.
There is some sliding along the teeth due to the different spiral angles of the pinion and the crown (larger gear), but it is consistent both longitudinally and in the direction of the tooth profile.
Related: What are Gears? Their Types, Diagram and How it Works
Applications
Below are the applications of hypoid gearboxes:
- The system is used in differentials of rear-wheel drive cars, trucks, and robotic arms.
- They can also utilize larger gears to enhance contact surface area and reduce wear and tear.
- Hypoid gearboxes reduce friction and energy loss, improving power transmission efficiency.
- They are commonly used in the automotive industry, particularly in rear axles for large trucks.
- The below-center offset in the system allows the driveshaft to be located lower in the vehicle, reducing interference with interior space.
- Hypoid gearboxes are generally used when speed exceeds 1000 RPM but are also suitable for lower-speed applications requiring smooth running or quiet operation.
- Finally, they are often used in the output stage in multi-stage gears for lower speeds and high torques.
Parts and Diagram
How Do Hypoid Gearboxes Work?
They are cone-shaped gears that transfer motion between shafts that do not intersect, much like spiral bevel gears. The bigger gear shaft, known as the hypoid gear side, is offset from the smaller gear shaft, known as the hypoid pinion side.
When the pinion shaft and big gear shaft are properly offset, they can pass one another without interfering, allowing the shafts to be firmly supported on both ends.
A conical surface and a line-contacting surface of revolution make up its pitch surface (an inscribed cone may be used as a replacement, although it has point-contacts).
In general, hypoid gears may achieve more speed reduction than bevel gears. Compared to bevel gears of the same size, its greater contact ratio is suitable for a gearbox of larger loads.
The perfect meshing of the system also makes it possible to further reduce vibration and noise. The manufacturing process is more challenging, though, and the meshing is quite intricate.
As previously stated, one set of hypoid gears may provide a very large speed decrease. Hypoid gear drives often offer the following benefits over worm gear drives with comparable high-speed reduction.
It is possible to heat treat the pinion and gear, which increases stiffness and makes the unit smaller. also, smaller capacity motors are the result of increased efficiency and less slippage.
There is less space required because of the tiny offset between the pinion and gear as compared to the worm.
Advantages
Below are the benefits of a hypoid gearbox:
- Increases machine design flexibility by allowing axis extension in both directions and adjustable axis height.
- Broadens pinion diameter due to larger spiral angle of pinion than gear, enhancing tooth strength and lifetime.
- Reduces the number of teeth due to a high contact ratio, allowing for a higher speed ratio than a bevel gear.
- Ensures satisfactory lubrication conditions due to sliding characteristics at all points.
Disadvantages
The disadvantages of a hypoid gear include complex design, lower efficiency level than a planetary gearbox, and not being suitable for fast speeds.
Related: What is Gear Teeth? its Diagram and Types
FAQs
What is a hypoid gear?
Hypoid gears are a unique category of spiral bevel gears that are used to transmit rotational power between two shafts at right angles. Invented by Ernest Wildhaber in the early 1920s, hypoid gears were used predominantly in the drive trains of heavy trucks.
What is the main benefit of a hypoid gear?
The main purpose for using these gearboxes is the bevel pinion can work with a larger spiral angle due to the axis offset. This increases the total number of gear teeth engaged.
This in turn means that hypoid gearboxes can transmit more torque in the same space compared to simple spiral gearing.
What are the disadvantages of hypoid gears?
One potential disadvantage of hypoid bevel gears is that they are more complex to manufacture than straight bevel gears, which can lead to higher manufacturing costs. Additionally, the offset shape of the teeth means that they require specialized lubrication to prevent excessive wear.
In which cases hypoid gear is used?
A hypoid gear is used when the included angle is square and the distance between axes is relatively small. The hypoid gear is viewed as an intermediate between a bevel gear and a worm gear machine.
What are the applications of hypoid gears?
Hypoid gears are normally used in right-angle drives associated with the axles of automobiles. Tooth actions combine the rolling action characteristic of spiral-bevel gears with a degree of sliding, which makes this type of gear critical from the point of view of surface loading.
