Worm gears are often used when large acceleration reductions are needed. The reduction ratio depends upon the number of begins of the worm and quantity of the teeth on the worm equipment. But worm gears possess sliding get in touch with which is silent but tends to produce heat and also have relatively low transmitting efficiency.
As for the materials for creation, in general, worm is made of hard metal while the worm gear is manufactured out of relatively soft metal such as for example aluminum bronze. That is since the number of tooth on the worm equipment is relatively high in comparison to worm with its number of begins being usually 1 to 4, by reducing the worm gear hardness, the friction on the worm teeth is reduced. Another characteristic of worm manufacturing is the need of specific machine for gear cutting and tooth grinding of worms. The worm gear, on the other hand, may be made with the hobbing machine used for spur gears. But due to the different tooth shape, it isn’t possible to cut many gears at once by stacking the gear blanks as can be done with spur gears.
The applications for worm gears include equipment boxes, angling pole reels, guitar string tuning pegs, and in which a delicate swiftness adjustment by utilizing a sizable speed reduction is necessary. While you can rotate the worm equipment by worm, it is usually not possible to rotate worm by using the worm gear. That is called the personal locking feature. The self locking feature cannot continually be assured and another method is recommended for true positive reverse prevention.
Also there exists duplex worm gear type. When using these, you’ll be able to modify 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 type of worm.
The worm equipment is more commonly called worm wheel in China.
A worm gear is a gear comprising a shaft with a spiral thread that engages with and drives a toothed wheel. Worm gears are an old style of equipment, and a edition of 1 of the six simple machines. Essentially, a worm equipment can be a screw butted up against what looks like a standard spur gear with somewhat angled and curved tooth.
It changes the rotational movement by 90 degrees, and the plane of movement also changes because of the placement of the worm on the worm wheel (or simply “the wheel”). They are typically comprised of a metal worm and a brass wheel.
Worm Gear
Figure 1. Worm equipment. Most worms (but not all) are at the bottom.
How Worm Gears Work
An electric electric motor or engine applies rotational power via to the worm. The worm rotates against the wheel, and the screw face pushes on the teeth of the wheel. The wheel is definitely pushed against the load.
Worm Gear Uses
There are some reasons why one would 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 small effort – all one must do can be add circumference to the wheel. Hence you can use it to either greatly increase torque or greatly reduce speed. It will typically take multiple reductions of a typical gearset to attain the same reduction level of a one worm gear – meaning users of worm gears possess fewer shifting parts and fewer places 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 really is virtually impossible for a wheel with pressure used to it to start 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 select a worm gear over a standard gear: lubrication. The motion between the worm and the wheel equipment faces is completely sliding. There is no rolling component to the tooth contact or conversation. This makes them relatively difficult to lubricate.
The lubricants required are often high viscosity (ISO 320 and higher) and thus are hard to filter, and the lubricants required are usually specialized in what they perform, requiring something to be on-site specifically for that type of equipment.
Worm Gear Lubrication
The main problem with a worm gear is how it transfers power. It is a boon and a curse at the same time. The spiral movement allows huge amounts of reduction in a comparatively little bit of space for what is required if a standard helical gear were used.
This spiral motion also causes an incredibly problematic condition to be the primary mode of power transfer. This is often called sliding friction or sliding wear.
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With an average gear set the energy is transferred at the peak load point on the tooth (known as the apex or pitchline), at least in a rolling wear condition. Sliding happens on either side of the apex, but the velocity is relatively low.
With a worm gear, sliding motion may be the only transfer of power. As the worm slides across the tooth of the wheel, it slowly 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 area leaves the wheel surface, it accumulates more lubricant, and starts the process once more on the next revolution.
The rolling friction on a typical gear tooth requires little in the way of lubricant film to fill in the spaces and separate the two components. Because sliding happens on either aspect of the apparatus tooth apex, a somewhat higher viscosity of lubricant than is certainly strictly necessary for rolling wear must overcome that load. The sliding occurs at a relatively low velocity.
The worm on a worm set gear turns, even though turning, it crushes against the strain that’s imposed on the wheel. The only way to prevent the worm from touching the wheel is definitely to have a film thickness huge enough never to have the entire tooth surface wiped off before that portion of the worm has gone out of the load zone.
This scenario requires a special kind of lubricant. Not just will it will have to be a relatively high viscosity lubricant (and the higher the strain or temperature, the higher the viscosity must be), it must have some way to help conquer the sliding condition present.
Read The Right Way to Lubricate Worm Gears for more information on this topic.
Viscosity is the major factor in stopping the worm from touching the wheel in a worm equipment set. While the load and size of gearing determines the mandatory lubricant, an ISO 460 or ISO 680 is rather common, and an ISO 1000 is not unheard of. If you have ever really tried to filter this selection of viscosity, you understand it is problematic because it is likely that non-e of the filters or pumps you have got on-site will be the appropriate 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 takes a slower operating pump to prevent the lubricant from activating the filter bypass. It will require a huge surface area filter to allow the lubricant to movement through.
Lubricant Types to Look For
One lubricant type commonly used with worm gears is mineral-based, compounded gear oils. There are no additives that can be put into a lubricant that may make it overcome sliding wear indefinitely, but the natural or synthetic fatty additive combination in compounded gear oils results in great lubricity, providing an extra way of measuring protection from metal-to-metal get in touch with.
Another lubricant type commonly used with worm gears is mineral-based, industrial extreme pressure (EP) gear oils. There are several problems with this kind of lubricant in case you are using a worm equipment with a yellow steel (brass) component. However, for those who have relatively low operating temps or no yellow metal present on the gear tooth surfaces, this lubricant is effective.
Polyalphaolefin (PAO) equipment lubricants work very well in worm equipment applications because they naturally have good lubricity properties. With a PAO gear oil, it is necessary to view the additive bundle, because these can have EP additives. A standard-duty antiwear (AW) fortified gear essential oil will typically end up being acceptable, but check that the properties are compatible with most metals.
The writer recommends to closely view the put on metals in oil analysis testing to ensure that the AW package isn’t so reactive as to trigger significant leaching from the brass. The effect should be much less than what will be noticed with EP even in a worst-case situation for AW reactivity, nonetheless it can arrive in metals testing. If you need a lubricant that can deal with higher- or lower-than-typical temps, a suitable PAO-based product is likely available.
Polyalkylene glycols (PAG), a fourth type of lubricant, are getting more prevalent. These lubricants have superb lubricity properties, and do not contain the waxes that trigger low-temperature issues with many mineral lubricants, making them an excellent low-temperature choice. Caution should be taken when using PAG oils because they are not appropriate for mineral oils, and some seals and paints.
Metallurgy of Worm Gears
The most typical worm gears are made with a brass wheel and a steel worm. This is because the brass wheel is typically easier to replace compared to the worm itself. The wheel is manufactured out of brass since it is designed to be sacrificial.
When the two surfaces enter into contact, the worm is marginally safe from wear because the wheel is softer, and therefore, most of the wear occurs on the wheel. Oil analysis reports on this kind of unit more often than not show some level of copper and low degrees of iron – as a result of the sacrificial wheel.
This brass wheel throws another problem into the lubrication equation for worm gears. If a sulfur-phosphorous EP gear essential oil is put into the sump of a worm gear with a brass wheel, and the temperature is usually high enough, the EP additive will activate. In regular steel gears, this activation creates a thin level of oxidation on the surface that helps to protect the apparatus tooth from shock loads and other 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 shed a substantial portion of the load surface of the wheel and cause major damage.
Other Materials
Some of the less common materials within worm gear sets include:
Steel worm and steel worm wheel – This program does not have the EP problems of brass gearing, but there is absolutely no room for error built into a gearbox like this. Repairs on worm equipment sets with this combination of metal are usually more costly and additional time eating than with a brass/steel worm gear set. This is because 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 found in moderate to light load situations because the brass can only hold up to a lower quantity of load. Lubricant selection on this metal combination is flexible due to the lighter load, but one must still consider the additive restrictions regarding EP because of the yellow metal.
Plastic on metal, on plastic, and other similar combinations – This is typically found in relatively light load applications, such as for example robotics and automotive components. The lubricant selection depends upon the plastic used, because many plastic varieties react to the hydrocarbons in regular lubricant, and thus will require silicon-based or other nonreactive lubricants.
Although a worm gear will always have a couple of complications compared to a standard gear set, it can easily be a highly effective and reliable device. With a little focus on set up and lubricant selection, worm gears can offer reliable service and also any other kind of gear set.
A worm drive is one simple worm gear set system in which a worm meshes with a worm gear. Even it is simple, 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 essential motion control element providing large swiftness reductions. It can decrease the rotational quickness or increase the torque output. The worm drive movement advantage is they can transfer movement in right angle. It also has an interesting home: the worm or worm shaft can certainly turn the gear, however the gear can not really turn the worm. This worm drive self-locking feature let the worm gear includes a brake function in conveyor systems or lifting systems.
An Intro to Worm Gearbox
The most important applications of worm gears is utilized in worm gear box. A worm gearbox is called a worm decrease gearbox, worm gear 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 container shell. So, the gearbox housing must have sufficient hardness. Otherwise, it will result in lower tranny quality. As the worm gearbox has a durable, transmitting ratio, small size, self-locking capability, and simple framework, it is used across a wide variety of industries: Rotary desk or turntable, materials dosing systems, auto feed machinery, stacking machine, belt conveyors, farm choosing lorries and more automation sector.
How to Select High Efficient Worm Gearbox?
The worm gear production process is also relatively simple. However, there is a low transmission effectiveness problem if you don’t know the how to choose the worm gearbox. 3 basic point to choose high worm gear efficiency that you should know:
1) Helix angle. The worm equipment drive efficiency mostly rely on the helix position of the worm. Usually, multiple thread worms and gears can be more efficient than one thread worms. Proper thread worms can increase efficiency.
2) Lubrication. To select a brand lubricating oil is an essential factor to improve worm gearbox efficiency. As the proper lubrication can decrease worm gear action friction and heat.
3) Material selection and Gear Manufacturing Technology. For worm shaft, the material should be hardened metal. The worm gear material ought to be aluminium bronze. By reducing the worm equipment hardness, the friction on the worm tooth is reduced. In worm manufacturing, to use the specific machine for gear reducing and tooth grinding of worms can also increase worm gearbox performance.
From a sizable transmission gearbox capacity to an even small worm gearbox load, you can choose one from a wide variety 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 should be solid and reliable.
3) Ensure that you check the connection between the motor and the worm gear reducer.
4) You must make use of flexible cables and wiring for a manual set up.
With the help of the innovative science and drive technology, we’ve developed several unique “square box” designed from high-quality aluminium die casting with a beautiful appearance. The modular worm gearbox style series: worm drive gearbox, parallel shaft gearbox, bevel helical gearbox, spiral bevel gearbox, coaxial gearbox, correct angle gearbox. An NMRV series gearbox can be a standard worm gearbox with a bronze worm equipment and a worm. Our Helical gearbox product line comprises of four universal series (R/S/K/F) and a step-less swiftness variation UDL series. Their structure and function act like an NMRV worm gearbox.
Worm gears are made of a worm and a equipment (sometimes referred to as a worm wheel), with nonparallel, nonintersecting shafts oriented 90 degrees to one another. The worm is analogous to a screw with a V-type thread, and the gear is definitely analogous to a spur equipment. The worm is typically the driving component, with the worm’s thread advancing the teeth of the gear.
Just like a ball screw, the worm in a worm gear might have an individual start or multiple starts – meaning that there are multiple threads, or helicies, on the worm. For a single-start worm, each full change (360 degrees) of the worm increases the equipment by one tooth. So a gear with 24 teeth will provide a gear reduced amount of 24:1. For a multi-begin worm, the gear reduction equals the amount of teeth on the gear, divided by the amount of starts on the worm. (This is different from most other types of gears, where in fact the gear reduction can be a function of the diameters of both components.)
The worm in a worm gear assembly can have one start (thread) or multiple starts.
Image credit: Kohara Gear Sector 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 heat, which limits the efficiency of worm gears to 30 to 50 percent. In order to minimize friction (and for that reason, temperature), the worm and gear are constructed with dissimilar metals – for example, the worm may be produced of hardened steel and the gear made of bronze or aluminum.
Although the sliding contact decreases efficiency, it provides very quiet operation. (The usage of dissimilar metals for the worm and equipment also contributes to quiet operation.) This makes worm gears ideal for use where noise should be minimized, such as for example in elevators. In addition, the utilization of a softer materials for the gear means that it could absorb shock loads, like those experienced in heavy equipment or crushing machines.
The primary benefit of worm gears is their capability to provide high reduction ratios and correspondingly high torque multiplication. They can also be used as acceleration reducers in low- to medium-acceleration applications. And, because their decrease ratio is based on the number of gear teeth only, they are smaller sized than other types of gears. Like fine-pitch business lead screws, worm gears are usually self-locking, making them ideal for hoisting and lifting applications.
A worm gear reducer is one kind of reduction gear container which includes a worm pinion input, an output worm gear, and features a right angle output orientation. This type of reduction gear container is generally used to take a rated motor acceleration and produce a low speed output with higher torque value based on the reduction ratio. They often can solve space-saving problems since the worm gear reducer is among the sleekest decrease gearboxes available due to the small diameter of its output gear.
worm gear reducerWorm gear reducers are also a popular type of rate reducer because they provide the greatest speed reduction in the smallest package. With a higher ratio of speed decrease and high torque result multiplier, it’s unsurprising that lots of power transmission systems utilize a worm gear reducer. Some of the most typical applications for worm gears can be found in tuning instruments, medical examining equipment, elevators, security gates, and conveyor belts.
Torque Transmission offers two sizes of worm gear 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 of these options are manufactured with tough compression-molded glass-fill polyester housings for a long lasting, long lasting, light-weight speed reducer that’s also compact, noncorrosive, and nonmetallic.
Our worm gear reducers offer an option of a good or hollow result shaft and show an adjustable mounting position. Both the SW-1 and the SW-5, nevertheless, can endure shock loading much better than other decrease gearbox designs, making them ideal for demanding applications.
Rugged compression-molded glass-fill up 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
Technical Info
Low friction coefficient on the gearing for high efficiency.
Powered by long-enduring worm gears.
Minimum speed fluctuation with low noise and low vibration.
Lightweight and compact in accordance with its high load capacity.
Compact design
Compact design is one of the key words of the standard 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 smooth operating of the worm gear combined with the use of cast iron and high precision on component manufacturing and assembly. In connection with our precision gearboxes, we consider extra treatment of any sound that can be interpreted as a murmur from the apparatus. Therefore the general noise level of our gearbox can be reduced to a complete minimum.
Angle gearboxes
On the worm gearbox the input shaft and output shaft are perpendicular to one another. This frequently proves to be a decisive advantage making the incorporation of the gearbox substantially simpler and smaller sized.The worm gearbox is an angle gear. This is an advantage 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 well suited for immediate suspension for wheels, movable arms and other areas rather than having to create a separate suspension.
Self locking
For larger equipment ratios, BJ-Gear’s worm gearboxes will provide 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 ideal for an array of solutions.

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