These gearboxes have a unique construction, in that they have a steel shaft and a gear made of bronze (brass) or aluminum. The shell or body of the helical gearbox is made of cast iron or aluminum, which has good resistance to vibration.
Other components of helical gearboxes include bearings and shafts. In these gearboxes, the shaft can be directly connected to the existing electric motor.
NMRV Manual Helical Gearbox
The NMRV book worm gearbox is of interest to small and medium industries due to its low manufacturing cost, small dimensions and installation capability. These gearboxes are used in many cases, such as elevator gearboxes, elevator gearboxes, conveyor gearboxes, mixer gearboxes, etc.
The self-locking of helical gearboxes is one of the features of this type of industrial gearboxes, which is useful information about it in the blog of Sam Tehiz.
The most widely used helical gearbox in the market is the Chinese helical gearbox , which has received attention due to its reasonable price and acceptable quality. Chinese NMRV helical gearboxes can be offered from 1:75 to 1:100 conversion ratio, which have irreversibility in 1:30 to 1:60 ratios, which is very important in elevator gearboxes and inclined conveyor gearboxes.
Contact numbers: 66268920 – 66278904
Iranian helical gearbox (VF – MVF)
Iranian helical gearboxes have a Mardon in the upper part and a Berenchi gear in the lower part. These gearboxes are widely used in various industries due to their low manufacturing cost and diverse capabilities.
Iranian helical gearboxes are the most used as lifting gearboxes. Also, Iranian helical motor gearboxes are the best-selling and most widely used gearboxes produced in the country. Iranian VF series helical gearboxes have the ability to be coupled with a belt or chain due to the input of the shaft, and they have irreversible properties in the ratios of 1:40 to 1:60. Iranian helical gearboxes are widely used as elevator gearboxes, conveyor belt gearboxes , etc. Among the manufacturers of helical gearboxes is Isfahan Sahand Gearbox Company, which produces various types of helical gearboxes, which on the dedicated page of Sahand helical gearboxes . can be seen
Three main types of helical gearboxes
- Non-throttle : A helical gearbox with a straight worm. The toothed contact is a single moving point on the worm drive that results in the transmission bearing heavy loads and high wear.
- Monoglot : It has concave spiral teeth that wrap around the cochlea. This interaction results in contact with the line and carries heavier loads without excessive wear.
- Doglu : It is also known as cone or hourglass. It has concave teeth on both the worm gear and the helical gear. Being equipped with 2 throats increases the line contact area which allows for increased loading and less wear.
What is the correct way to lubricate the worm gear?
Helical gearboxes are used in a wide variety of applications due to their ability to reduce speed in a small enclosure and also due to their locking properties; But choosing the right fluid for worm gearbox lubrication requires more than choosing the right viscosity. Stay with us to talk about the effect of worm gearbox lubrication on its performance quality and the correct method of lubrication of this type of gearboxes.
The importance of worm gearbox lubrication
The following factors affect the efficiency of the helical gearbox:
- Snail lead angle
- sliding speed
- Quality, concentration, viscosity and amount of lubricant
- Quality Level
- Installation conditions
Most types of gearboxes , such as helical, bevel and spur, experience sliding and rotating contact when the teeth engage and mesh, but worm gearboxes mainly work with sliding contact between the gear and the worm wheel. This predominantly sliding contact results in significant friction and very high operating temperatures. Therefore, gearboxes mainly work under boundary lubrication conditions. The result of these factors is that worm gearboxes require lubricants that can operate under considerable heat and pressure, in addition to providing excellent lubricating properties.
At first glance, lubricants with extreme pressure (EP) additives seem to be suitable; But there’s a catch: EP additives often contain active sulfur or chlorine, both of which can damage yellow metals by softening them. (Most worm gears are made from a single piece of steel for the worm gear section and a bronze gear.) To reduce these harmful effects, some EP lubricants now use deactivated sulfur.
Types of recommended oils
In an effort to find an oil that can withstand the operating conditions of worm gear assemblies without reacting with the bronze gear, some manufacturers and worm gear lubrication specialists recommend the use of compound oils consisting of a mineral oil base with acid-free or acid tallow. They are made of grease and combined with anti-rust and oxidation.
Compound oils have better lubrication that reduces friction and wear. However, they have a temperature limit of approximately 80°C (176°F). Above this temperature, oxidation increases rapidly and acid products are produced which can damage the bronze gearbox.
Synthetic lubricants are another alternative that, although they have a higher initial cost, can significantly improve the efficiency and service life of worm gear assemblies. These oils for worm gearbox lubrication are usually divided into two categories: polyalphaolefin (PAO) and polyalkylene glycol (PAG) synthetic oils. PAOs have lower viscosity and higher viscosity index. Therefore, they can be used in a wider range of temperatures. Most of them have anti-wear additives. PAOs with EP additives are also available.
Similarly, PAGs have a high viscosity index and a wide operating temperature range. Also, compared to other types of oils, they have higher lubrication properties. PAGs contain antiwear additives, but unlike PAOs, synthetic PAG oils are not available with EP additives. The composition of PAGs is incompatible with paints, sealants and polycarbonates.
Use of improper or insufficient oil
Using the wrong type of oil for lubrication or insufficient lubrication are two of the most common causes of worm gear failure. In addition to choosing the right type of worm gear lubricant and lubrication, making sure that the worm gear has the right amount of lubricant is very important for proper operation. Lubrication of the worm gearbox is usually done by the splash method. Also, another unique feature of helical gearbox lubrication is that it plays an important role in determining the amount of lubrication required for installation.
Helical gearboxes are usually installed upside down, where the helical part is placed on top of the gearbox; But they can also be installed in the direction of the photo. To ensure proper lubrication in the downward direction, the gearbox assembly requires up to 50% more lubricant than in the upward direction.
Various types of gearboxes are used as speed reducers, such as helical gearboxes, hanging gearboxes , etc., in many industries and applications. Worm gearboxes also require unique lubrication requirements as they operate under harsh conditions. The helical gearbox has one of the simplest and most useful designs, but the lubrication of helical gearboxes is not as simple as their design and they require special oil and lubrication.
How long is the life of the helical gearbox?
Worm gearboxes usually have a long life and due to their special construction and wide range of applications, in many cases, these gearboxes are usually used for years. In addition, the simple design and few mechanical components reduce the maintenance cost. However, to maintain the useful life of the worm gear, oil changes and periodic cleaning are required. It is also necessary to test the quality of the no-load cycle to check the performance and condition of the mechanical components of the gearbox. If the gearbox is not selected correctly or the installation and initial settings of the gearbox are incorrect, it may cause high pressure and heat in the gearbox, which reduces its useful life. In addition, if they are used in certain environments such as environments with adverse weather conditions, they require more replacement and maintenance. In general, following the manufacturer’s instructions and proper maintenance can help maintain the useful life and improve the performance of the worm gear.