The Definitive Guide to Right Angle Gearboxes

Welcome to the W.C. Branham Right Angle Gearbox Guide. We hope you find the information unbiased and insightful. Our goal is to help you understand the variety of applications for right angle gearboxes/drives, how to choose the right gearbox for your unique application, how to choose the appropriate supplier/manufacturer, and how to maintain, repair, or replace your right angle gearboxes. 

Please feel free to click any of the links below to jump straight to the section you desire:

1. What is a Right Angle Gearbox?

2. Types of Right Angle Gearboxes

3. Selecting the Appropriate Gearbox for Your Application

4. Selecting the Appropriate Gearbox Supplier

5. How to Extend the Life of Your Gearboxes

6. When to Repair vs. Replace Gearboxes

If you're short on time, you can download this guide as a PDF by clicking the link below.

What is a Right Angle Gearbox?

A right angle gearbox is one in which the input shaft and the output shaft meet at a 90^o angle. This configuration allows for torque to be transmitted from one axis to a perpendicular axis—using rotation to transfer power.

Right angle gearboxes are used in numerous types of mechanical designs, including automotive transmissions and industrial applications. Gearboxes are ideal in these settings because they are compact, efficient, reliable, and durable.

At Branham, we manufacture a wide range of helical, worm gear, and spiral bevel gearboxes. Don’t worry, we’ll discuss the options later in this guide.

Types of Right Angle Gearboxes

While there are sub-varieties within these main categories, there are 4 main types of gearboxes:

1. Worm

2. Bevel

3. Helical

4. Planetary

Worm Gearboxes

A worm gear set actually looks a lot like it sounds—there's a worm that drives a gear. The worm, a shaft with a spiral thread, engages with and drives the gear. This design enables control over rotational direction, helps regulate speed and adds higher torque transmission. 

There are many sub-varieties of worm gears, including single-throated, non-throated, and double-throated.

• Non-throated. Instead of a continuous thread, this style has a single moving point that contacts the gear. The minimal contact makes this type of worm drive most vulnerable to wear and tear from high unit load.

• Single-throated. This variation can withstand high unit loads with less wear. Its concave helix wraps around the worm, making continuous contact with the gear.

• Double-throated (called hourglass or cone). This style can withstand the highest unit loads without excessive wear and tear, because it has concave teeth on both the worm and the gear, doubling the contact area.

Worm drives can be designed with right-hand or left-hand gearing, allowing them to turn either clockwise or counterclockwise. With an internal helical gear, both parts must be the same hand. With external helical gears that function in parallel, the hands must be opposite.

Worm gears are used in low to moderate-horsepower applications. They offer low initial cost, high ratios, and high output torque in a small package. You should consider using worm gears in these situations:

• A high ratio is needed in a compact package. Worm gears can have a low number of threads, so higher ratios can be accomplished with fewer gears.

• Quiet operation is required. The sliding action of worm gears is quieter than other gear types.

• When back driving is not desirable. Since worm gears only work in one direction, their self-locking characteristics aid braking and avoid back driving.

Worm gears are less efficient than most other gear combinations. Their typical efficiency ranges from 50-90%, depending on gear ratio, lead angle, and friction factor. For comparison, helical gears range from 94-98% efficiency, while the efficiency of spiral bevel gears ranges from 95-99%.

Branham manufactures three types of right angle (worm drive) gearboxes (hollow bore single shaft, hollow bore double shaft, and hollow bore only), and each model can be spec’d in numerous bore sizes and gear ratios.

Bevel Gearboxes

Years ago, it was expensive and very difficult to make spiral bevel gearboxes. And while the precision necessary to craft such beautiful and intricate pieces is still tricky, with the right attention to design and fabrication, it's much more doable.

A bevel gearbox, as its name suggests, contains two interlocking bevel gears. On a standard gear, the pitch surface (that carries the teeth) is cylindrical. On a bevel gear, the pitch face is conical. The angle formed by the pitch face and the axis on which it’s mounted is called the pitch angle. Often, bevel gears work at right angles, but they can be designed to function at any pitch angle. A hand drill is an example of a tool that uses a 90^o bevel gear.

Bevel gears are classified by their geometry, and each type of bevel gear offers its own specialty or advantage. Here is a list of bevel gear examples:

• Straight Bevel Gear. On a straight bevel gear, the teeth are straight but they taper toward the apex of the cone-shaped surface. This is the most common type of bevel gear. It functions well, but the operation can be noisy, especially at high speeds or under heavy loads.

• Spiral Bevel Gear. On a spiral bevel gear, the teeth are curved and set in a spiral so they contact their counterparts more gradually. This smoother operation eliminates the noise (and higher risk of tooth breakage) of a straight bevel gear.

  
• Zerol® Bevel Gear. A zerol® bevel gear also has curved teeth, but they are not angled in a spiral, so the teeth align with the axis.

• Hypoid Bevel Gear. On a hypoid bevel gear, the pitch angle is hyperbolic instead of conical and the pinion can be offset—either below or above the gear center.

By nature, bevel gear design is highly complex—even intricate. So it takes meticulous planning to design and manufacture to achieve the desired operational result.

The many advantages of bevel gear design include:

• Bevel gears are on-plane. The input and output shafts are at a perfect right angle to each other, not offset vertically. The alternative, a hollow bore helical gearbox, cannot provide this direct transfer of power at a right angle in the same plane. This allows a spiral bevel gearbox to simply turn a corner to deliver the power you need where you need it.

• Bevel gears are precise. With less than half of a degree of backlash, there is little torque or power wasted in the slop of the gearbox. This is a feature of the intricate spiral bevel gear design which has to be made to very exacting specifications.

• Bevel gears can easily be made into a three-way coupling. Power can be transmitted left, right, or in both directions with the same shafts. This makes for a handy way to split the power from one motor to operate several things at once, saving on motor cost and maintenance.

• Bevel gears have a long life. Because of the tight tolerances in a spiral bevel gear design, there is very little wear between the teeth. This gives them a very long operating cycle with minimal maintenance other than basic lubrication.

Helical Gearboxes

This design produces greater thrust and radial loads and operates at lower temperatures, so it is extra efficient and lasts a long time. Helical gearboxes operate smoothly, quietly, and efficiently. They are a good choice for high-horsepower industrial applications such as packaging, cutting, and labeling, but they’re most commonly used in transmissions.

Other benefits of helical gearbox design include:

• Helical gears can bear greater loads. As mentioned, helical gears are similar to spur gears but with the gear teeth produced at an angle to the axis of the gear. This allows helical gears to bear more load than spur gears and operate more quietly.

• Helical gears are more versatile. They can be used in both parallel (in-line) as well as right angle configurations. They’re also produced with the gear tooth helix direction in both right and left hand orientations. (Keep in mind, helical gear sets used in parallel must use one right and one left hand gear.)

• Helical gears offer greater range. When used in parallel, multiple helical gears may be used to offer a wide range of gear ratios and distances between input/output shafts.

• Helical gear sets offer more flexibility compared to standard spur gears. For example, when used in right angles, you can use either two right hand or two left gears depending on the desired output rotation direction.

• Right angle helical gearboxes can have a greater range of gear diameters. This helps helical gearboxes achieve various ratios as well as distance between input/output shafts. 

• Right angle helical gearboxes provide non-intersecting shafts. This means the input/output shafts are offset from one another at a distance determined by the gear diameters. Offset shafts can extend in both directions—offering the opportunity to connect multiple gearboxes or accessories to the shaft.

Fun fact: Here at Branham, we pioneered right angle hollow bore helical gearboxes. Learn more about that design and helical gearboxes in our article, “Helical or Spiral Bevel: Commonly Used Gearboxes in Packaging Machinery”.

Planetary Gearboxes

An age-old design, the planetary gearbox got its name because the different gears move together like planets. A center gear turns, moving multiple gears around it, mirroring the gravitational pull of planets in our solar system.

Planetary gearboxes have multiple benefits: Because the torque is divided over 3 gears at equal dimensions, the torque is almost 3x higher than typical gearboxes. They’re also compact and therefore have a low mass inertia.

Keep in mind, not every solution requires a cookie-cutter gearbox—in fact, many applications have unique challenges that just can’t be satisfied by one of the basic options. If you have custom needs, please don’t hesitate to give us the specs and we can explore custom solutions together!

Selecting the Appropriate Gearbox for Your Application

Within the world of gearboxes, there are so many configurations that choosing the right product for your particular mechanical design can be challenging. Nowadays, custom gearboxes are more and more common, chiefly because manufacturing to specification is easier than ever, with newer machine tools as well as design and automation software. 

So, when determining the right angle gearbox that will work best for your mechanical design, it’s important to identify the key aspects of your design and application. That should be an easy task using our Gearbox Selection Checklist. Click below to check it out!

In addition to the checklist questions, there are four important factors to consider when choosing your gearbox design:

1. Size

2. Performance Capability

3. Mounting Requirements

4. Environmental Conditions

Size

Some of the most common mistakes made in the engineering design process have to do with improper sizing. Our standard-size right angle gearboxes range from 2.87 to 6.6 inches tall. A more compact option is the MICROGEAR series (the smallest of which is under 1.5 cubic inches). We know that it's best to find an exact fit, which is why we specialize in custom design products, too. 

Check out this video on right angle gearbox sizing from our very own VP of Engineering and General Manager, Chad Randleman.

As Chad stated, the three areas you need to consider when sizing a right angle gearbox are:

1. Required Torque for the Application. Along with the required output torque, you’ll need to know what’s required for your application in terms of RPM and shaft rotation. IAS Gearboxes are available in both left- and right-hand rotation, which determines the output shaft rotation in relation to the input.

2. Radial or Axial Loading of the Application. If you have radial or axial loading applied to your gearbox shaft, you’ll want to account for that and support the shafting externally using bearing blocks.

3. Duty Cycle of the Application. For light to moderate duty applications, gearboxes would be considered lubricated and lubed for life. For more severe duty applications, it’s advised that you put them on a regular maintenance schedule for relubrication.

Performance Capability

What are your horsepower and input speed requirements? What about target output speed or torque? Consider load support—you’ll need bearing blocks to support overhung, axial, or external moment loads; otherwise, the load could shift to the internal gears, pushing them out of alignment.

Reliability is crucial for any industrial equipment, but most of all when machinery is operating under high-speed, high-torque conditions. For these applications, a high-speed right angle gearbox is often the best design choice to ensure cost-effective, long-lasting, safe performance.

High-speed automation is common in applications such as packaging, bottling lines, and other food processing operations, pulp and paper manufacturing, heavy manufacturing such as cement or steel, and mining. And locations such as car washes, food, and beverage operations, or medical facilities typically use high-speed roll-up doors.

The gearbox you choose will affect operational efficiency, reliability, overall performance, and long-term cost. Before you make any design decisions, you’ll need to ask yourself a lot of questions. It’s best to start at the beginning: how the gearbox will be used. That will help you consider vital details such as:

• Output speed required, as well as the input speed

• The desired gear ratio (1:1, 2:1, 3:2, etc.)

• Duty cycle frequency including starts and stops required

• Environmental characteristics (washdown, caustic chemicals, and extreme temperatures can affect gearbox performance and life)

For some types of applications, you will also want to specify the acceptable amount of backlash (space between two meshing gears). This assures optimal lubrication, so the gears won’t lock up.

For more information on high-speed right angle gearboxes, click here.

Mounting Requirements

If your application demands a right angle gearbox, it’s important to know if your design calls for a left-hand or right-hand rotation.

The main differentiation between the right-hand and left-hand versions of right angle gearboxes is the rotation of the gear drives.

For example, if the A-Bore is rotated clockwise, the B-Bore would rotate clockwise with a right-hand configured gearbox and counter-clockwise with a left-hand configured gearbox.

With many standard types and sizes available, and the ability for specialty shaft configurations, ensuring the right angle gearbox for your application is key. Having multiple mounting options also helps simplify your design considerations.

Environmental Conditions

Will your gearbox have to withstand shock, vibration, or wet washdown conditions? Your gearbox may need corrosion-resistant materials or plating, or you may want to spec stainless steel shafts and housing.

You may be wondering, what are the best applications for stainless steel gearboxes?

• Food processing

• Beverage bottling

• Meat packing

• Pharmaceutical or medical device manufacturing

• Chemical processing

• Packaging equipment

• Marine industries

• Any wash-down application

Some operations require that gearboxes be lubricated with H1 or H2 food-grade grease. With stainless steel gearboxes, that doesn’t limit your design options.

Speaking of lubrication, the five common right angle gear drive lubrication options to remember for proper installation and maintenance depending on your particular operating conditions are:

1. Gearing Type

2. Loading

3. Gear Speed

4. Materials Compatibility

5. Ambient Temperature

Keep in mind, there’s also always the option of building a custom gearbox for stainless systems.

Custom

Custom and standard gearing aren’t mutually exclusive. Where fully custom gearboxes aren’t a feasible option (for example, quantities aren’t high enough), choosing a manufacturer with built-to-order gearboxes from standard modular subcomponents might be a wise choice. Look for manufacturers that employ the latest CAD software, CAM software, and machine tools to streamline post-processing work and reduce one-off costs.

After you’ve chosen a gearbox, it is advised to discuss your application with the manufacturer or their technical representative. Once installed, perform several test runs to replicate typical operating scenarios. If unusually high heat, noise, or stress is present, repeat the gear-selection process or contact your representative for assistance. You'll find that they are willing to assist you in making a successful installation for your application.

Selecting the Appropriate Gearbox Supplier

If you’re in the market for a right angle gearbox, you need to find a high quality gearbox supplier. But how can you determine whether someone is the “right” gearbox supplier?

Obviously, the first thing you’re going to do is confirm whether they manufacture the type of right angle gearbox you’re looking for. While you're at it, take note of their product selection. Do they offer multiple types of gearboxes? If so, that could mean they’re more flexible in their capabilities.

To make this a bit easier, refer again to our Gearbox Selection Checklist. If the supplier can check these boxes, they’re worth exploring further. 

It’s also important to see if they offer any custom gearbox solutions. Even if the application you’re working on today doesn’t need it, you may need a custom gearbox down the line! 

Pro tip: When visiting their website, try to see who they’ve worked with in the past and what they’ve accomplished. If the work they’ve done in the past lines up with the requirements of your application, they might be the right gearbox supplier for you. Be sure to also check their reviews online, if they have any!

How to Extend the Life of Your Gearboxes

The nature of automation and the laws of physics dictate that all moving parts wear out over time, and your right angle gearbox is no exception. Industrial settings are demanding and unforgiving. High speeds, high temperatures, wash down requirements, and other factors take their toll.

Right angle gearboxes require less maintenance than many other industrial components, but less maintenance doesn’t mean "no maintenance." Developing problems can damage seals, bearings, bolts, and other internal components or even cause the entire gearbox to fail. You can prevent untimely problems and extend right angle gearbox service life with a few simple precautions including preventative maintenance, ensuring the right product is selected during the design process, and implementing custom products when necessary. 

Check out this blog post for more information on maximizing the service life of your right angle gearbox.

When to Repair vs. Replace Gearboxes

Wear and tear is a fact of life for machinery operating in industrial settings that feature high temperatures, high speeds, outdoor dirt, or harsh washdowns. Nothing lasts forever, and even the highest quality components eventually break down.

Right angle gearboxes, in general, are low-maintenance. But if something goes wrong, how can you tell if you’re looking at gearbox repair versus replacement?

The sooner you detect emerging problems, the better your chances of a less costly repair instead of an untimely, expensive gearbox failure. Developing problems can also push gearbox components out of spec, which weakens performance and speeds further damage. 

Here are some signs to look for and steps you can take to troubleshoot gearbox problems.

• Overheating

• Leaks

• Misalignment

• Noise

• Unexpected Loads

Keep in mind that preventative maintenance is the most affordable approach to gearbox longevity. The time you spend now can keep operations running smoothly and save you both time and money later on. Here are some tips to help keep your gearboxes running smoothly.

• Regular inspection can uncover problems that lead to damaged seals as well as internal bearings, bolts, and so on. Look for grease leakage and any signs of wear on gears.

• Double-check alignment.

• Check for signs of heat buildup.

• Regularly clean the gearbox to help prevent possible contamination. Never use solvents to clean the exterior or any internal parts. Make sure the gearbox is properly lubricated.

We hope you found this guide to be helpful. It all boils down to understanding the requirements of your unique application, paired with an understanding of your right angle gearbox options. This video covers FAQs we get about gearboxes.

If you need any help, please don’t hesitate to contact the Branham team. We’ve been helping customers find solutions to their unique challenges for almost 40 years and look forward to the opportunity to serve you. 

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