Worm gears are usually used when large swiftness reductions are needed. The reduction ratio depends upon the number of starts of the worm and number of teeth on the worm equipment. But worm gears have sliding get in touch with which is peaceful but will produce heat and also have relatively low transmission effectiveness.
For the materials for production, in general, worm is made from hard metal as the worm gear is manufactured out of relatively soft steel such as aluminum bronze. This is since the number of the teeth on the worm gear is relatively high compared to worm using its number of starts being generally 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 specialized machine for gear cutting and tooth grinding of worms. The worm gear, on the other hand, may be made out of the hobbing machine used for spur gears. But because of the various tooth shape, it is not possible to cut a number of gears at once by stacking the apparatus blanks as can be done with spur gears.
The applications for worm gears include equipment boxes, angling pole reels, guitar string tuning pegs, and where a delicate velocity adjustment by utilizing a huge speed reduction is needed. While you can rotate the worm equipment by worm, it is normally not possible to rotate worm by using the worm gear. This is called the self locking feature. The self locking feature cannot continually be assured and another method is recommended for accurate positive reverse prevention.
Also there is duplex worm gear type. When working with these, it is possible to change backlash, as when one’s teeth put on necessitates backlash adjustment, without requiring a change in the center distance. There aren’t too many producers who can generate this kind of worm.
The worm equipment is additionally called worm wheel in China.
A worm equipment 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 gear, and a edition of 1 of the six simple machines. Essentially, a worm gear can be a screw butted up against what appears like a typical spur gear with slightly angled and curved teeth.
It changes the rotational motion by 90 degrees, and the plane of motion also changes because of the placement of the worm upon the worm wheel (or simply “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 the bottom.
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 definitely pushed against the load.
Worm Gear Uses
There are some reasons why one would select a worm gear more than a standard gear.
The first one may be the high reduction ratio. A worm equipment can have an enormous reduction ratio with small effort – all one should do is add circumference to the wheel. Hence you can utilize it to either greatly increase torque or greatly reduce speed. It’ll typically take multiple reductions of a conventional gearset to attain the same reduction level of a single worm equipment – meaning users of worm gears possess fewer shifting parts and fewer areas for failure.
A second reason to employ a worm gear may be the inability to reverse the path of power. Due to the friction between the worm and the wheel, it really is virtually impossible for a wheel with pressure applied to it to start the worm moving.
On a standard gear, the input and output could be switched independently once enough force is applied. This necessitates adding a backstop to a standard gearbox, further increasing the complication of the apparatus 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 movement between the worm and the wheel equipment faces is completely sliding. There is absolutely no rolling element of the tooth contact or conversation. This makes them fairly difficult to lubricate.
The lubricants required are often very high viscosity (ISO 320 and higher) and therefore are tough to filter, and the lubricants required are usually specialized in what they perform, requiring something to be on-site specifically for that kind of equipment.
Worm Gear Lubrication
The main problem with a worm gear is how it transfers power. It is a boon and a curse simultaneously. The spiral movement allows huge amounts of decrease in a comparatively little bit of space for what is required if a standard helical equipment 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 put on.
New call-to-action
With a typical gear set the energy is transferred at the peak load stage 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 may be the only transfer of power. As the worm slides over the tooth of the wheel, it slowly rubs off the lubricant film, until there is no lubricant film remaining, and as a result, the worm rubs at the metallic of the wheel in a boundary lubrication regime. When the worm surface leaves the wheel surface, it picks up more lubricant, and begins the process over again on another revolution.
The rolling friction on a typical gear tooth requires little in the form of lubricant film to complete the spaces and separate the two components. Because sliding happens on either side of the gear tooth apex, a somewhat higher viscosity of lubricant than can be strictly needed for rolling wear is required to overcome that load. The sliding occurs at a relatively low velocity.
The worm on a worm set gear turns, and while turning, it crushes against the load that’s imposed on the wheel. The only method to prevent the worm from touching the wheel can be to get a film thickness huge enough to not have the entire tooth surface wiped off before that part of the worm has gone out of the strain zone.
This scenario takes a special kind of lubricant. Not only will it will have to be a comparatively high viscosity lubricant (and the higher the load or temperature, the higher the viscosity must be), it must have some way to help get over the sliding condition present.
Read The Right Method to Lubricate Worm Gears to find out more on this topic.
Viscosity may be the major aspect in preventing 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 fairly common, and an ISO 1000 isn’t unheard of. If you’ve ever tried to filter this range of viscosity, you understand it is problematic because it is probable that none of the filters or pumps you possess on-site would be the appropriate size or ranking to function properly.
Therefore, you would likely need to get a particular pump and filter for this kind of unit. A lubricant that viscous takes a slow operating pump to prevent 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 consider
One lubricant type commonly used with worm gears is mineral-based, compounded equipment oils. There are no additives that can be put into a lubricant that can 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 measure of 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 type of lubricant in case you are using a worm equipment with a yellow metallic (brass) component. However, in case you have fairly low operating temps or no yellow metal present on the apparatus tooth areas, this lubricant works well.
Polyalphaolefin (PAO) gear lubricants work well in worm gear applications because they naturally possess great lubricity properties. With a PAO gear oil, it’s important to view the additive bundle, because these can have EP additives. A standard-duty antiwear (AW) fortified gear oil will typically become acceptable, but check that the properties are compatible with most metals.
The author recommends to closely view the put on metals in oil evaluation testing to ensure that the AW bundle isn’t so reactive concerning trigger significant leaching from the brass. The effect should be far less than what would be noticed with EP also in a worst-case scenario for AW reactivity, nonetheless it can show up in metals assessment. If you need a lubricant that may deal with higher- or lower-than-typical temperatures, a suitable PAO-based product is likely available.
Polyalkylene glycols (PAG), a fourth kind of lubricant, are getting more prevalent. These lubricants have superb lubricity properties, , nor contain the waxes that cause low-temperature problems with many mineral lubricants, making them a great low-temperature choice. Caution must be taken when working with PAG oils because they’re not appropriate for mineral oils, plus some seals and paints.
Metallurgy of Worm Gears
The most common worm gears are created with a brass wheel and a steel worm. This is since the brass wheel is normally easier to replace compared to the worm itself. The wheel is manufactured out of brass since it was created to be sacrificial.
When the two surfaces come into contact, the worm is marginally secure from wear since the wheel is softer, and therefore, most of the wear occurs on the wheel. Oil evaluation reports on this type of unit almost always show some degree of copper and low levels of iron – consequently of the sacrificial wheel.
This brass wheel throws another problem into the lubrication equation for worm gears. If a sulfur-phosphorous EP gear oil is placed into the sump of a worm equipment with a brass wheel, and the temperature can be high enough, the EP additive will activate. In regular metal gears, this activation creates a thin layer of oxidation on the top that helps to protect the gear tooth from shock loads and other extreme mechanical conditions.
On the brass surface however, the activation of the EP additive outcomes in significant corrosion from the sulfur. In a brief amount of time, you can drop a significant portion of the strain 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 software does not have the EP problems of brass gearing, but there is absolutely no room for mistake included in a gearbox like this. Repairs on worm equipment sets with this mixture of metal are usually 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 app is most likely found in moderate to light load circumstances because the brass can only hold up to a lesser quantity of load. Lubricant selection on this metal mixture 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, upon plastic, and other similar combinations – That is typically within relatively light load applications, such as robotics and automotive components. The lubricant selection depends on the plastic used, because many plastic types 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 couple of complications compared to a typical gear set, it can easily be an effective and reliable device. With a little attention to setup and lubricant selection, worm gears can provide reliable service and also any other type of gear set.
A worm drive is one particular worm gear set mechanism when a worm meshes with a worm gear. Even it is simple, there are two essential components: worm and worm gear. (They are also called the worm and worm wheel) The worm and worm wheel is important motion control element providing large swiftness reductions. It can reduce the rotational speed or increase the torque output. The worm drive motion advantage is that they can transfer movement in right angle. In addition, it has an interesting property: the worm or worm shaft can simply turn the apparatus, but the gear cannot turn the worm. This worm drive self-locking feature let the worm gear has a brake function in conveyor systems or lifting systems.
An Introduction to Worm Gearbox
The most crucial applications of worm gears can be used in worm gear box. A worm gearbox is named a worm reduction gearbox, worm gear reducer or a worm drive gearbox. It consists of worm gears, shafts, bearings, and box frames.
The worm equipment, shafts, bearings load are supported by the box shell. So, the gearbox housing must have sufficient hardness. Otherwise, it will result in lower tranny quality. As the worm gearbox includes a durable, transmitting ratio, small size, self-locking ability, and simple framework, it is often used across a wide selection of industries: Rotary table or turntable, materials dosing systems, auto feed machinery, stacking machine, belt conveyors, farm selecting lorries and more automation industry.
How to Select High Efficient Worm Gearbox?
The worm gear manufacturing process can be relatively simple. However, there exists a low transmission effectiveness problem if you don’t understand the how to choose the worm gearbox. 3 basic indicate choose high worm gear efficiency that you need to know:
1) Helix position. The worm equipment drive efficiency mostly rely on the helix angle of the worm. Usually, multiple thread worms and gears can be more efficient than one thread worms. Proper thread worms can increase effectiveness.
2) Lubrication. To choose a brand lubricating essential oil is an essential factor to boost worm gearbox effectiveness. As the proper lubrication can reduce worm gear action friction and warmth.
3) Material selection and Gear Manufacturing Technology. For worm shaft, the material should be hardened metal. The worm gear material should be aluminium bronze. By reducing the worm equipment hardness, the friction on the worm teeth is reduced. In worm manufacturing, to use the specific machine for gear cutting and tooth grinding of worms can also increase worm gearbox performance.
From a big transmission gearbox power to a straight 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 may complete the installation in six different ways.
2) The installation must be solid and reliable.
3) Make sure to examine the connection between your motor and the worm equipment reducer.
4) You must make use of flexible cables and wiring for a manual set up.
With the help of the most advanced science and drive technology, we’ve developed several unique “square package” designed from high-quality aluminium die casting with a beautiful 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 definitely a typical worm gearbox with a bronze worm equipment and a worm. Our Helical gearbox products consists of four universal series (R/S/K/F) and a step-less quickness variation UDL series. Their structure and function are similar to an NMRV worm gearbox.
Worm gears are constructed of a worm and a equipment (sometimes known as a worm wheel), with non-parallel, nonintersecting shafts oriented 90 degrees to each other. The worm can be analogous to a screw with a V-type thread, and the gear can be analogous to a spur equipment. The worm is typically the driving component, with the worm’s thread advancing the teeth of the gear.
Such as a ball screw, the worm in a worm gear might 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 change (360 degrees) of the worm advances the gear by one tooth. So a gear with 24 teeth provides a gear reduction of 24:1. For a multi-begin worm, the apparatus reduction equals the amount of teeth on the apparatus, divided by the number of begins on the worm. (This is different from almost every other types of gears, where in fact 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 actions causes friction and temperature, which limits the effectiveness of worm gears to 30 to 50 percent. In order to minimize friction (and for that reason, heat), the worm and gear are made from dissimilar metals – for example, the worm could be made of hardened steel and the gear made of bronze or aluminum.
Although the sliding contact decreases efficiency, it provides extremely quiet operation. (The usage of dissimilar metals for the worm and equipment also plays a part in quiet procedure.) This makes worm gears suitable for use where sound should be minimized, such as in elevators. In addition, the use of a softer material for the apparatus means that it could absorb shock loads, like those experienced in heavy equipment or crushing machines.
The primary advantage of worm gears is their ability to provide high reduction ratios and correspondingly high torque multiplication. They can also be used as swiftness reducers in low- to medium-speed applications. And, because their reduction ratio is based on the number of gear teeth by itself, they are smaller sized than other styles of gears. Like fine-pitch business lead screws, worm gears are typically self-locking, making them perfect for hoisting and lifting applications.
A worm equipment reducer is one type of reduction gear package which includes a worm pinion insight, an output worm equipment, and includes a right angle result orientation. This type of reduction gear package is generally used to take a rated motor swiftness and create a low speed output with higher torque worth based on the decrease 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 equipment reducers are also a favorite type of quickness reducer because they provide the greatest speed decrease in the smallest package. With a higher ratio of speed decrease and high torque result multiplier, it’s unsurprising that many power transmission systems make use of a worm equipment reducer. Some of the most common applications for worm gears can be found in tuning instruments, medical screening equipment, elevators, security gates, and conveyor belts.
Torque Transmission offers two sizes of worm equipment reducer, the SW-1 and the SW-5 and both are available in a variety 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 up polyester housings for a durable, long lasting, light weight speed reducer that is also compact, non-corrosive, and nonmetallic.
Features
Our worm equipment reducers offer a choice of a solid or hollow output shaft and feature an adjustable mounting position. Both the SW-1 and the SW-5, however, can endure shock loading much better than other reduction gearbox styles, making them well suited 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
Overview
Technical Info
Low friction coefficient on the gearing for high efficiency.
Powered by long-lasting 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 among the key phrases of the standard gearboxes of the BJ-Series. Further optimisation can be achieved by using adapted gearboxes or unique gearboxes.
Low noise
Our worm gearboxes and actuators are extremely quiet. This is due to the very clean operating of the worm gear combined with the use of cast iron and high precision on element manufacturing and assembly. Regarding the our precision gearboxes, we take extra treatment of any sound which can be interpreted as a murmur from the gear. Therefore the general noise level of our gearbox can be reduced to an absolute 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 advantage producing the incorporation of the gearbox considerably simpler and smaller sized.The worm gearbox is an angle gear. This is an edge for incorporation into constructions.
Solid bearings in solid housing
The output shaft of the BJ worm gearbox is quite firmly embedded in the gear house and is perfect for immediate suspension for wheels, movable arms and other areas rather than needing to build a separate suspension.
Self locking
For larger gear ratios, BJ-Gear’s worm gearboxes provides a self-locking impact, which in many situations can be used as brake or as extra protection. Also spindle gearboxes with a trapezoidal spindle are self-locking, making them ideal for a wide selection of solutions.

You can find out more info about worm wheel gearbox on our website.