worm wheel gearbox

Worm gears are usually used when large velocity reductions are needed. The decrease ratio depends upon the number of starts of the worm and quantity of the teeth on the worm gear. But worm gears possess sliding contact which is noiseless but tends to produce heat and also have relatively low transmission efficiency.
As for the materials for production, in general, worm is made from hard metal while the worm gear is manufactured out of relatively soft metal such as aluminum bronze. That is since the number of the teeth on the worm gear is relatively high compared to worm with its number of begins being generally 1 to 4, by reducing the worm gear hardness, the friction on the worm teeth is reduced. Another feature of worm manufacturing may be the need of specialized machine for gear trimming and tooth grinding of worms. The worm equipment, however, may be made out of the hobbing machine used for spur gears. But because of the different tooth shape, it is not possible to cut several gears at once by stacking the gear blanks as can be done with spur gears.
The applications for worm gears include equipment boxes, fishing pole reels, guitar string tuning pegs, and where a delicate rate adjustment by utilizing a large speed reduction is needed. While you can rotate the worm equipment by worm, it is usually extremely hard to rotate worm utilizing the worm gear. This is called the self locking feature. The self locking feature cannot continually be assured and a separate method is recommended for true positive reverse prevention.
Also there is duplex worm gear type. When using these, it is possible to adjust backlash, as when the teeth put on necessitates backlash adjustment, without needing a change in the center distance. There aren’t too many producers who can create this kind of worm.
The worm gear is additionally called worm wheel in China.
A worm gear is a gear consisting of a shaft with a spiral thread that engages with and drives a toothed wheel. Worm gears are an old style of equipment, and a version of 1 of the six basic machines. Fundamentally, a worm equipment is certainly a screw butted up against what looks like a standard spur gear with somewhat angled and curved the teeth.
It changes the rotational movement by 90 degrees, and the plane of movement also changes because of the placement of the worm upon the worm wheel (or just “the wheel”). They are typically comprised of a steel worm and a brass wheel.
Worm Gear
Figure 1. Worm gear. Most worms (however, not all) are at underneath.
How Worm Gears Work
An electric engine or engine applies rotational power via to the worm. The worm rotates against the wheel, and the screw encounter pushes on one’s teeth of the wheel. The wheel is usually pushed against the load.
Worm Gear Uses
There are a few reasons why you might choose a worm gear over a standard gear.
The first one is the high reduction ratio. A worm equipment can have an enormous reduction ratio with little effort – all one should do is definitely add circumference to the wheel. Thus you can utilize it to either significantly increase torque or greatly reduce speed. It’ll typically consider multiple reductions of a typical gearset to attain the same reduction degree of a single worm equipment – which means users of worm gears possess fewer moving parts and fewer locations for failure.
A second reason to use a worm gear is the inability to reverse the path of power. Because of the friction between your worm and the wheel, it is virtually difficult for a wheel with drive applied to it to begin the worm moving.
On a standard equipment, the input and output can be switched independently once enough force is used. This necessitates adding a backstop to a standard gearbox, further raising the complication of the gear set.
Why Not to Use Worm Gears
There is one particularly glaring reason why one would not choose a worm gear more than a standard gear: lubrication. The movement between the worm and the wheel equipment faces is entirely sliding. There is absolutely no rolling component to the tooth get in touch with or interaction. This makes them relatively difficult to lubricate.
The lubricants required are usually very high viscosity (ISO 320 and better) and therefore are tough to filter, and the lubricants required are usually specialized in what they perform, requiring something to be on-site particularly for that kind of equipment.
Worm Gear Lubrication
The main problem with a worm gear is how it transfers power. It really is a boon and a curse at the same time. The spiral movement allows large sums of decrease in a comparatively little bit of space for what is required if a typical helical gear were used.
This spiral motion also causes an incredibly problematic condition to be the principal mode of power transfer. That is commonly known as sliding friction or sliding use.
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With an average gear set the power is transferred at the peak load point on the tooth (referred to as the apex or pitchline), at least in a rolling wear condition. Sliding takes place on either aspect of the apex, but the velocity is fairly low.
With a worm gear, sliding motion is the only transfer of power. As the worm slides across the tooth of the wheel, it gradually rubs off the lubricant film, until there is absolutely no lubricant film still left, and for that reason, the worm rubs at the steel of the wheel in a boundary lubrication regime. When the worm surface leaves the wheel surface area, it accumulates more lubricant, and begins the process over again on the next revolution.
The rolling friction on an average gear tooth requires small in the way of lubricant film to fill in the spaces and separate the two components. Because sliding happens on either aspect of the gear tooth apex, a slightly higher viscosity of lubricant than is usually strictly needed for rolling wear must overcome that load. The sliding takes place at a relatively low velocity.
The worm on a worm set gear turns, and while turning, it crushes against the strain that is imposed on the wheel. The only way to avoid the worm from touching the wheel is definitely to have a film thickness large enough to not have the entire tooth surface wiped off before that area of the worm has gone out of the strain zone.
This scenario takes a special sort of lubricant. Not just will it will have to be a relatively high viscosity lubricant (and the higher the load or temperature, the bigger the viscosity should be), it will need to have some way to help overcome the sliding condition present.
Read The Right Way to Lubricate Worm Gears to find out more on this topic.
Viscosity is the major factor in avoiding the worm from touching the wheel in a worm gear set. While the load and size of gearing determines the required lubricant, an ISO 460 or ISO 680 is rather common, and an ISO 1000 isn’t unheard of. If you’ve ever tried to filter this selection of viscosity, you know it really is problematic because it is likely that non-e of the filters or pumps you have on-site would be the proper size or rating to function properly.
Therefore, you would likely need to get a specific pump and filter for this kind of unit. A lubricant that viscous requires a sluggish operating pump to avoid the lubricant from activating the filter bypass. It will require a huge surface area filter to allow the lubricant to circulation through.
Lubricant Types to Look For
One lubricant type commonly used in combination with worm gears is mineral-based, compounded equipment oils. There are no additives that can be put into a lubricant that may make it conquer sliding wear indefinitely, but the natural or synthetic fatty additive mixture in compounded equipment oils results in great lubricity, providing an extra measure of protection from metal-to-metal contact.
Another lubricant type commonly used with worm gears is mineral-based, industrial extreme pressure (EP) gear oils. There are some problems with this type of lubricant in case you are using a worm gear with a yellow metal (brass) component. However, for those who have relatively low operating temperatures or no yellow metal present on the apparatus tooth surfaces, this lubricant is effective.
Polyalphaolefin (PAO) equipment lubricants work well in worm gear applications because they naturally possess good lubricity properties. With a PAO gear oil, it is necessary to view the additive package, because these can have EP additives. A standard-duty antiwear (AW) fortified gear oil will typically be acceptable, but be sure the properties are appropriate for most metals.
The author recommends to closely view the use metals in oil evaluation testing to ensure that the AW package isn’t so reactive concerning cause significant leaching from the brass. The effect should be far less than what will be seen with EP also in a worst-case situation for AW reactivity, nonetheless it can arrive in metals examining. If you need a lubricant that can manage higher- or lower-than-typical temperature ranges, the right PAO-based product is likely available.
Polyalkylene glycols (PAG), a fourth type of lubricant, are becoming more prevalent. These lubricants have exceptional lubricity properties, and don’t support the waxes that cause low-temperature problems with many mineral lubricants, making them a great low-temperature choice. Caution should be taken when working with PAG oils because they’re not appropriate for mineral oils, and some seals and paints.
Metallurgy of Worm Gears
The most common worm gears are made with a brass wheel and a steel worm. That is because the brass wheel is typically easier to replace than the worm itself. The wheel is manufactured out of brass since it is designed to be sacrificial.
When the two surfaces come into contact, the worm is marginally safe from wear since the wheel is softer, and for that reason, most of the wear occurs on the wheel. Oil evaluation reports on this kind of unit more often than not show some degree of copper and low degrees of iron – consequently of the sacrificial wheel.
This brass wheel throws another problem in to the lubrication equation for worm gears. If a sulfur-phosphorous EP gear oil is put into the sump of a worm equipment with a brass wheel, and the temperature is high enough, the EP additive will activate. In normal metal gears, this activation produces a thin coating of oxidation on the surface that helps to protect the apparatus tooth from shock loads and additional extreme mechanical conditions.
On the brass surface area however, the activation of the EP additive results in significant corrosion from the sulfur. In a brief timeframe, you can drop a substantial portion of the load surface of the wheel and cause major damage.
Other Materials
Some of the less common materials found in worm gear models include:
Steel worm and steel worm wheel – This application does not have the EP problems of brass gearing, but there is no room for mistake built into a gearbox such as this. Repairs on worm gear sets with this combination of metal are typically more costly and more time eating than with a brass/steel worm equipment set. This is since the material transfer connected with failure makes both worm and the wheel unusable in the rebuild.
Brass worm and brass worm wheel – This program is most likely within moderate to light load circumstances because the brass can only keep up to a lower quantity of load. Lubricant selection upon this metal mixture is flexible due to the lighter load, but one must still consider the additive restrictions regarding EP due to the yellow metal.
Plastic on metal, on plastic, and other similar combinations – That is typically within relatively light load applications, such as robotics and auto components. The lubricant selection depends upon the plastic in use, because many plastic varieties respond to the hydrocarbons in regular lubricant, and therefore will demand silicon-based or other nonreactive lubricants.
Although a worm gear will will have a few complications compared to a standard gear set, it can certainly be a highly effective and reliable device. With a little focus on set up and lubricant selection, worm gears can provide reliable service along with any other kind of gear set.
A worm drive is one particular worm gear set mechanism in which a worm meshes with a worm equipment. Even it is basic, there are two important elements: worm and worm gear. (They are also known as the worm and worm wheel) The worm and worm wheel is important motion control component providing large velocity reductions. It can reduce the rotational quickness or raise the torque output. The worm drive motion advantage is they can transfer motion in right angle. It also has an interesting home: the worm or worm shaft can simply turn the gear, but the gear can not turn the worm. This worm drive self-locking feature let the worm gear has a brake function in conveyor systems or lifting systems.
An Launch to Worm Gearbox
The most crucial applications of worm gears can be used in worm gear box. A worm gearbox is named a worm decrease gearbox, worm equipment reducer or a worm drive gearbox. It consists of worm gears, shafts, bearings, and box frames.
The worm gear, shafts, bearings load are supported by the box shell. So, the gearbox housing will need to have sufficient hardness. Or else, it will lead to lower tranny quality. As the worm gearbox comes with a durable, transmission ratio, little size, self-locking capability, and simple structure, it is often used across a wide variety of industries: Rotary table or turntable, material dosing systems, car feed machinery, stacking machine, belt conveyors, farm choosing lorries and more automation industry.
How to Select High Efficient Worm Gearbox?
The worm gear production process is also relatively simple. Nevertheless, there is a low transmission performance problem if you don’t understand the how to select the worm gearbox. 3 basic point to choose high worm gear efficiency that you need to know:
1) Helix angle. The worm equipment drive efficiency mostly depend on the helix angle of the worm. Generally, multiple thread worms and gears is definitely more efficient than one thread worms. Proper thread worms can increase efficiency.
2) Lubrication. To choose a brand lubricating oil can be an essential factor to boost worm gearbox efficiency. As the proper lubrication can decrease worm equipment action friction and warmth.
3) Material selection and Gear Production Technology. For worm shaft, the material ought to be hardened metal. The worm gear material should be aluminium bronze. By reducing the worm gear hardness, the friction on the worm teeth is reduced. In worm manufacturing, to use the specialized machine for gear trimming and tooth grinding of worms can also increase worm gearbox efficiency.
From a large transmission gearbox power to an even small worm gearbox load, you can choose one from an array of worm reducer that precisely fits your application requirements.
Worm Gear Package Assembly:
1) You can complete the set up in six various ways.
2) The installation must be solid and reliable.
3) Make sure to examine the connection between the motor and the worm gear reducer.
4) You must make use of flexible cables and wiring for a manual installation.
With the help of the most advanced science and drive technology, we have developed several unique “square package” designed from high-quality aluminium die casting with a lovely appearance. The modular worm gearbox design series: worm drive gearbox, parallel shaft gearbox, bevel helical gearbox, spiral bevel gearbox, coaxial gearbox, correct angle gearbox. An NMRV series gearbox is certainly a typical worm gearbox with a bronze worm equipment and a worm. Our Helical gearbox product line consists of four universal series (R/S/K/F) and a step-less rate variation UDL series. Their structure and function are similar to an NMRV worm gearbox.
Worm gears are made of a worm and a gear (sometimes known as a worm wheel), with nonparallel, nonintersecting shafts oriented 90 degrees to one another. The worm is certainly analogous to a screw with a V-type thread, and the gear is usually analogous to a spur gear. The worm is normally the generating component, with the worm’s thread advancing the teeth of the gear.
Just like a ball screw, the worm in a worm gear may have an individual start or multiple starts – and therefore there are multiple threads, or helicies, on the worm. For a single-start worm, each complete switch (360 degrees) of the worm advances the gear by one tooth. So a gear with 24 teeth provides a gear reduced amount of 24:1. For a multi-begin worm, the apparatus reduction equals the amount of teeth on the gear, divided by the number of starts on the worm. (That is different from most other types of gears, where the gear reduction is definitely a function of the diameters of both components.)
The worm in a worm gear assembly can have one start (thread) or multiple starts.
Picture credit: Kohara Gear Market Company, Ltd.
The meshing of the worm and the apparatus is a mixture of sliding and rolling actions, but sliding contact dominates at high reduction ratios. This sliding action causes friction and high temperature, which limits the performance of worm gears to 30 to 50 percent. In order to minimize friction (and for that reason, temperature), the worm and equipment are constructed with dissimilar metals – for instance, the worm could be made of hardened metal and the gear made of bronze or aluminum.
Although the sliding contact reduces efficiency, it provides extremely quiet operation. (The use of dissimilar metals for the worm and gear also plays a part in quiet operation.) This makes worm gears ideal for use where noise should be minimized, such as in elevators. Furthermore, the utilization of a softer materials for the gear means that it could absorb shock loads, like those skilled in heavy equipment or crushing devices.
The primary benefit of worm gears is their ability to provide high reduction ratios and correspondingly high torque multiplication. They can also be used as rate reducers in low- to medium-swiftness applications. And, because their reduction ratio is based on the number of gear teeth only, they are more compact than other styles of gears. Like fine-pitch lead screws, worm gears are usually self-locking, which makes them perfect for hoisting and lifting applications.
A worm gear reducer is one type of reduction gear container which contains a worm pinion insight, an output worm equipment, and includes a right angle result orientation. This kind of reduction gear container is generally used to have a rated motor rate and create a low speed result with higher torque worth based on the decrease ratio. They often can resolve space-saving problems because the worm gear reducer is among the sleekest decrease gearboxes available due to the little diameter of its result gear.
worm gear reducerWorm gear reducers are also a popular type of swiftness reducer because they provide the greatest speed decrease in the smallest package. With a higher ratio of speed reduction and high torque output multiplier, it’s unsurprising that lots of power transmission systems utilize a worm equipment reducer. Some of the most typical applications for worm gears are available in tuning instruments, medical testing equipment, elevators, protection gates, and conveyor belts.
Torque Transmission provides two sizes of worm equipment reducer, the SW-1 and the SW-5 and both are available in a range of ratios. The SW-1 ratios include 3.5:1 to 60:1 and the SW-5 ratios include 5:1 to 100:1. Both these options are produced with durable compression-molded glass-fill polyester housings for a durable, long lasting, light weight speed reducer that’s also compact, non-corrosive, and nonmetallic.
Features
Our worm gear reducers offer an option of a solid or hollow result shaft and show an adjustable mounting position. Both the SW-1 and the SW-5, nevertheless, can withstand shock loading better than other decrease gearbox designs, making them ideal for demanding applications.
Rugged compression-molded glass-fill polyester housing
Light weight and compact
Non corrosive
Non metallic
Range of ratios
SW-1, 3.5:1 to 60:1
SW-5, 5:1 to 100:1
Grease Lubrication
Solid or Hollow output shaft
Adjustable mounting position
Overview
Technical Info
Low friction coefficient on the gearing for high efficiency.
Powered by long-lasting worm gears.
Minimal speed fluctuation with low noise and low vibration.
Lightweight and compact in accordance with its high load capacity.
Compact design
Compact design is among the key terms of the typical gearboxes of the BJ-Series. Further optimisation may be accomplished by using adapted gearboxes or special gearboxes.
Low noise
Our worm gearboxes and actuators are extremely quiet. This is due to the very soft working of the worm equipment combined with the use of cast iron and high precision on component manufacturing and assembly. In connection with our precision gearboxes, we consider extra care of any sound that can be interpreted as a murmur from the gear. So the general noise level of our gearbox is usually reduced to a complete minimum.
Angle gearboxes
On the worm gearbox the input shaft and output shaft are perpendicular to one another. This often proves to be a decisive benefit making the incorporation of the gearbox substantially simpler and more compact.The worm gearbox can be an angle gear. This is often an edge for incorporation into constructions.
Strong bearings in solid housing
The output shaft of the BJ worm gearbox is very firmly embedded in the gear house and is perfect for direct suspension for wheels, movable arms and other areas rather than having to build a separate suspension.
Self locking
For larger equipment ratios, BJ-Gear’s worm gearboxes provides a self-locking impact, which in many situations can be used as brake or as extra security. Also spindle gearboxes with a trapezoidal spindle are self-locking, making them perfect for a wide selection of solutions.

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