Worm Gearbox Repairs - Highfield Gears

Worm Gearbox Repairs

Of the many gear units we can repair here at Highfield Gears, worm gear units are one of our specialities. Since our founding in 1927, the experts here have been repairing, reconditioning and upgrading gearboxes of this nature and can solve virtually every problem that could occur thanks to our range of in-house equipment. From gear cutting and gear grinding to our fitting bays, load test facilities and CNC machines, we have everything available to help deliver a cost-effective solution for your business.

WHAT IS A WORM GEARBOX?
BENEFITS OF WORM GEARBOX
WHY WORM GEARBOX REPAIR IS A COST-EFFECTIVE SOLUTION

We’re passionate about power transmissions and gearbox repairs for worm gearboxes, bevel gearboxes, bevel helical gearboxes, the list goes on. We believe that it is a much more efficient solution than merely buying a brand new one, which can cost thousands. We funnel this passion into ensuring your once broken worm, bevel, helical, bevel helical gearbox is repaired and back to its original strength. We’ll use great care and precision and mix that with speed and efficiency so that downtime is reduced and you have a gear unit that is operating at optimum capacity.

As well as these types of gearboxes, we can also repair a range of other industrial gearboxes such as double helical gearboxes, extruder gearboxes, planetary gearboxes and spur gearboxes. We also have the in-house equipment to manufacture a series of gear spares and pieces such as worm gears, helical gears, spur gears, bevel gears, double helical gears and many more.

If you have a worm gearbox, bevel gearbox, helical gearbox, bevel helical gearbox that requires a repair then please get in touch for a chat with our team here at Highfield Gears by phone on 01484 531 010 or online. We are based in Huddersfield so if you’re located in the nearby towns and cities of Sheffield, Barnsley, Doncaster or you operate in another major town or city in the UK or Europe we’d be delighted to help you.

What Is a Worm Gearbox?

In its most basic form, these types of gear units are constructed of a worm and a gear with a non-parallel, non-intersecting shaft that is positioned at a 90-degree angle to each other. Typically, the worm shaft is the driving component and the worm thread advances the teeth of the gear. A worm gear unit will have single or multiple states because of the multiple threads and helices found on the worm.

A key feature of worm gear units is the use of different materials because the meshing of the worm and gear slides in operation which can cause a huge amount of friction and heat. To ensure there is a reduction in this kind of activity both the worm and the gear have to be made of different materials. For instance, you could have a bronze alloy wheel and a worm piece made of a hardened carbon steel alloy.

At Highfield Gears, we offer a wide range of worm gearbox configurations. Their modular design results in countless different combinations when it comes to gear housings, mountings, connections, shaft designs and oil treatments. Thankfully, our team has worked with a series of worm gear units that have these combinations and can repair and improve each and everyone, using quality materials, to their exacting standards regardless of configuration. We ensure that all the worm wheels and gears we repair, no matter the gearbox size, are fitted with precision seals, to prevent dust or water from entering, and are able to recommend a safe lubricant such as synthetic oil to ensure smooth running.

How Do Worm Gears Work?

A worm gear is an old style of gear, unlike, for example, the more advanced components that power a planetary gearbox. As a result, they operate in a very simple way. When the solid shaft, which is made into a spiral shape, rotates 90 degrees it changes the position of the wheel.

The teeth of the worm wheel (wheel for short) are pulled through each spiral until they come out the other end. The efficiency of worm gears comes from their simplicity. They only have two components, both of which are solidly made and rarely break. Worm gears can have what’s known as different ‘starts’. This term refers to the threads in the shaft, the more threads there are, the quicker the teeth can be pulled through. If you have an application that needs to work at high speed, such as a drill, then you’d want more threads.

What Is A Worm Gear Used For?

There are two main reasons why you would choose to use a worm gearbox over a standard one. They are: 

  1. The high reduction ratio: You’re able to increase torque or greatly reduce speed very easily with these gearboxes. A worm gear can have a high reduction ratio without causing too much trouble. To achieve it, you simply add another circumference to the wheel. The result of this is that you typically rely on fewer moving parts while still achieving your objectives because the ratios can be dialled up quickly and easily. 
  2. Inability to reverse: A second reason is that a worm cannot reverse the direction of power. It’s nearly impossible for a wheel with force applied to it to move the worm. This provides peace of mind and is unlike a normal gearbox which can be turned independently if enough force is applied.

What Is Gear Efficiency?

Gear efficiency can seem like a complicated topic but it's important in figuring out how efficient your gearbox is.

To calculate the efficiency of your gearbox you must first divide output shaft power by input shaft power (you can calculate the output shaft power by taking the power losses away from the input power). Then, times that number by 100 to get a final percentage. Below is the equation.

EQUATION: Gear Efficiency = (output shaft power/input shaft power) x 100

One of the best ways to keep efficiency high is to make sure you have the best wear protection (i.e. lubrication) for your gears. The best way of doing this is by switching to synthetic lubricants. In fact, with worm gearboxes, in particular, efficiency can be improved greatly by changing lubrication because it has a high sliding friction percentage which can cause issues.

Getting good efficiency levels is key to making sure you’re not spending thousands of pounds on gear repairs.

Are Worm Gears Efficient?

Not really, no, their sliding action (which pulls the teeth through the spirals) can cause high levels of friction and heat which keeps efficiency levels between 30-50%. While inefficient, it does mean that worm gears are extremely quiet. This means they can be used in applications while near silence is paramount, such as a lift.

Worm gear efficiency depends on the speed-reduction ratio. The higher ratio units have smaller gear teeth, which result in more surface contact between the wheel and worm. All in all, though, the lack of efficiency is made up for in the fact that you only need to maintain a handful of parts to enjoy all the benefits from this type of transmission unit.

Benefits Of Worm Gearbox

The primary benefit of worm gearboxes is their ability to provide high reduction ratios and high torque multiplication and can be used as speed reducers in low to medium speed applications and machinery. What follows are some other important benefits of these types of gearboxes.

Compact, Simple Design With Maximum Strength

They are more compact than other gears because the aforementioned reduction ratio is based on the gear teeth alone. This compact design means they can be fitted in smaller places such as lift shafts or help absorb shock loads from heavy equipment such as crushing machines.

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Low Noise Operation

This series of gearboxes are extremely quiet due to the smooth running of the worm combined with our high precision component manufacturing of other components such as the worm wheel, housing and flanges. Low noise operation is a key feature and we ensure we remove any noise that could be misconstrued as a murmur from this series of gearboxes.

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Angle Gearboxes

As we mentioned, because the input shaft and output shaft are perpendicular to each other it makes the incorporation of the gearbox into machinery considerably easier and more compact. Having an angle gearbox is an advantage for several industries such as the steel and manufacturing sector.

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Good Bearing Strength In Solid Housing

The mounting options on the gearbox mean the output shaft is firmly embedded in the gearbox casing making it incredibly sturdy and ideal to power wheels and movable arms and saves you having to build a separate suspension.

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Self Locking Modern Design

Larger worm gearboxes have a self-locking effect and can be used as a brake in emergencies, this offers an extra layer of security for businesses.

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Why Worm Gearbox Repair Is A Cost-Effective Solution

Repairing worm gearboxes is far more cost-efficient and effective than simply replacing it entirely. Our experts often encourage customers to consider a repair as opposed to replacement, not only is it cheaper but when you purchase a new worm gearbox you usually have to re-engineer it to fit your application or material as its footprint may be different - all this could cost you even more money in the long run.

We have a wide range of options available to use including re-working individual components or re-cutting, engineering, milling and boring new parts. Our worm gear experts have years of engineering drawings and can manufacture worm gear parts from a range of competitors which saves you a great deal of time and money.

We’re confident that for 90% of the time of problems, repairing your worm gearbox is the best option. This is because we make and manufacture everything in-house rather than wait for a 3rd party to create and ship the part to us. Making everything in house allows us to track the quality throughout ensuring they hit our standards every time. Everything that we do is documented and reported on, pictures are taken and explanations are given as to why we do what we do.

Why Are Worm Gears Made Of Bronze?

They are made of bronze, or other metals such as brass and copper, to reduce wear. Because worm gears are used to reduce speed and increase torque, the strength and resilience are increased by using bronze. Another reason they are made out of bronze is that it reduces the levels of heat and friction. This is especially true if the worm wheel is made out of aluminium or steel. Combine all this with the right synthetic lubrication and you have a pretty long-lasting transmission unit on your hands.

Are Worm Gears Self-locking?

Are Worm Gears Self-locking?

Yes. Self-locking in worm gearboxes can occur when it is static (i.e. not moving) or dynamic (i.e. moving). Generally, though, self-locking happens when the gear isn’t moving. If the coefficient of friction between the worm and the gear is greater than the tangent found in the worm’s lead angle, the gear will not reverse and will self-lock.

This is often described using the term ‘non-backdrivability’ and is associated with large reduction ratios, and the ability to hold output positions without consuming energy.

The fact that all this works, in theory, should not be relied upon where safety is concerned. It is important to make sure that your company has real, practical safety procedures in place to prevent sheared gears or broken gearboxes. This is because any sort of unexpected shock or vibration could cause the coefficient to dramatically drop (to, for example, 0.08), causing an unlocking.

Are Worm Gears Reversible?

Are Worm Gears Reversible?

As we’ve just touched on, the large reduction ratios mean that the worm gears’ direction of transmission (i.e. its input shaft vs output shaft) is not reversible. The lack of reversibility is because of the greater friction involved between the worm and the worm wheel. Those contact points are extremely pressurised and will not budge.

In some instances, there are reverse worm drives. To achieve this, the angle of the teeth must be greater than the angle to the axis. If this is achieved, the worm can then be driven by the wheel.

If You Need Worm Gearbox Repair Services Get In Touch

Our worm gearbox repair service is thorough, draws on decades of experience and involves cutting-edge technology – all this makes us confident we can help you. So, if you have a worm gearbox that is need of repair, reconditioning or upgrade and are based in the UK in areas such as Sheffield, Manchester, Aberdeen, Cardiff or further afield in Europe be sure to get in touch with us for a chat here at Highfield Gears on 01484 531 010 – we look forward to hearing from you.