Using gear lubricant when servicing an angle grinder

General symptoms

Before a complete malfunction, the angle grinder signals the beginning of a malfunction.

Pay attention to the work of your assistant: you should be careful if:

• The brushes began to spark too much;
• The coffee grinder becomes hot during operation;
• The motor hums inside the housing when the tool is turned on;
• The vibration of the body has become much greater when performing work;
• Inside the slot of the grinding device;
• You can hear the bearing creaking when rotating or periodically jamming when the rotor shaft rotates;
• The angle grinder is smoky or has an unusual burning odor.

How to disassemble an angle grinder

How to disassemble an angle grinder? It's not such a complicated process. This does not require special knowledge, but everything must be done carefully and with caution. Every owner needs to know how to disassemble any working tool, because periodically it needs internal cleaning from dirt and dust, and its service life depends on this.

Nowadays on the market you can choose different types of grinders, which differ in operating parameters, size, and quality. Manufacturers are also different. Whatever model of grinding machine you buy, they all have the same model for assembling parts.

Disassembling the angle grinder will require few tools; you just need a regular screwdriver or a reversible one with a ratchet mechanism.

Reasons for strong vibrations of the grinder

The source of this problem may be:

• Poor quality of the cutting or grinding wheel, their uneven wear.
• Contamination of mechanisms or severe wear of the mechanical part - bearings, shaft seat.
• Brushes are dirty.

If your grinder stops working, if it makes noise, vibrates a lot or overheats, it is recommended to contact a service center, which will not only fix the current problem, but also diagnose all components of the tool.

Why does the grinder spark strongly in the area of ​​the brushes?

During normal operation, a small, uniform spark is observed inside the housing. If it is too strong, the brushes must be replaced. The problem occurs in the following situations:

• Damage to the armature winding - an interturn short circuit has occurred or a section of the winding has broken.
• Loss of contact between the winding and the collector plates.
• Violation of insulation between the collector lamellas.
• Severely worn “grinder” bearings , which provoke the beating of the angle grinder’s armature, causing the brushes to spark and burn strongly.
• Using brushes whose characteristics do not correspond to the speed and voltage in the network.
• Motor overheating due to continuous operation for too long.

Why does the grinder heat up?

The electric motor overheats in the following cases:

• Incorrect operating mode. As a result of too high loads, the motor windings burn out.
• Destruction of armature bearings. The result is difficulty in operating the engine and, as a result, overheating.
• Clogged ventilation ducts through which air flows to the electric motor, acting as a cooler.
• Closing the turns of the stator and rotor windings.

The angle grinder gearbox overheats due to lack of lubrication or its poor quality.

Diagnostics of the electrical part of an angle grinder

As mentioned above, most often an angle grinder refuses to work due to breakdowns of the electrical part of the unit. To correctly diagnose the electrical circuits of a tool, electrical equipment repair technicians use a special device - a tester.

If you press the start button of the unit and it does not work, then in 90% of cases the cause of the breakdown is not so serious that you cannot repair the angle grinder yourself.

Experts advise adhering to the basic rule of repairing power tools: moving from simple to complex.

The first step is to check the electrical cable and the plug at its end. If it is collapsible, then unscrew it and check the reliability of the contacts. Otherwise, you will have to disassemble the angle grinder (remove the casing of the device) and “ring” the cable with a tester, and also make sure that the current is suitable for the contacts of the “Start” button. If the device shows a break, the cable should be replaced with a new one.

The situation when current flows to the button, but does not pass further (when in the on position), indicates a malfunction of the switch. The button cannot be repaired. It needs to be replaced with a new one, but first mark the contacts you are removing so that you can connect them correctly in the future. If the contacts are connected incorrectly, the motor winding may burn out.

If during the check it turns out that both the cable and the start button are in good condition, but no current is supplied to the brushes, then it is necessary to clean the contact plates of the brush holders. If this procedure is ineffective, it is recommended to replace the brushes. Next, if everything is fine with the brushes and current is flowing to them, you should check the rotor and stator for shorts and breaks.

Checking the motor armature

The electric motor rotor may have the following malfunctions: interturn short circuit and broken conductors at the lamella contacts. You can check the armature of an angle grinder with a multimeter: the device is switched to the resistance change mode, the value is set to 200 Ohms, and the resistance between two adjacent lamellas is measured using probes. Thus, it is necessary to check all pairs of lamellas. If the resistance values ​​are the same, then the rotor winding is not damaged. Detection of other resistance values ​​during “ringing”, as well as detection of an open circuit, indicates a malfunction in this coil. In this case, the angle grinder's anchor will need to be repaired.

Typically, conductor rupture occurs at the junction with the winding. Inspect the places where the coils are connected to the lamellas, make sure that the contacts are soldered securely.

If you do not have a measuring device, you can check the rotor using a 12 V light bulb and a battery for this purpose. The power should be between 30-40 W. The test is done as follows: apply 12 V voltage from the battery to the plug of the angle grinder, connect a light bulb to the gap in one wire, and start rotating the angle grinder spindle. If the winding is in good condition, the light will burn evenly, without blinking. With an interturn short circuit, the degree of incandescence of the light bulb filament will change. In this case, repairing the angle grinder's anchor with your own hands will be difficult, since the armature winding scheme is quite complex, and the process itself requires special equipment and knowledge. Therefore, it is recommended to entrust this operation to specialists. But the best way out of the situation would be to replace the anchor on the angle grinder with a new one.

Prevention, maintenance, diagnostics

Carrying out prevention of angle grinders significantly reduces the likelihood of sudden failure of a power tool. Ultimately, the costs of repair work are reduced, and the grinder’s resource indicators increase. It is necessary to carry out the following maintenance work regularly, approximately once a year (depending on the intensity of use of the grinder):

• brush assembly;
• remove the gear housing cover;
• disconnect the gearbox housing together with the rotor from the electrical part of the angle grinder;
• Remove the rotor shaft from the gear housing bearing after removing the drive gear.

Clean all interior and exterior surfaces.

Check the wear of the graphite brushes. If necessary, replace them following the following procedure:

• clean the brush holders;
• clean the collector lamellas;
• install new brushes.

The brush assembly located on the body of the Makita GA9020 angle grinder provides convenient replacement of brushes. Photo VseInstruments.ru

Determination of gearbox defects.

• visually check the wear of the tooth profile and the presence of chips;
• checking the shaft for play in the plain bearing or needle bearing;
• checking the remaining ball bearings for play and presence of lubricant;
• on shafts and gears with keyed connections, check the wear of the keys and grooves under them;
• if necessary, replace the sliding bushing, bearings, and lubricant.

Inspection of rotor parts.

• carry out an external inspection of the rotor and stator windings for the presence of darkened areas and damage to the varnish coating, which indirectly indicates the presence of an interturn short circuit and overheating;
• check the rotor bearings for play and presence of lubricant;
• Inspect the commutator surface for wear and other damage.

The gearbox on the grinder is heating up. One of the possible reasons.

Inspect the wiring for insulation damage. Check the status of the contacts.

Reassemble in reverse order.

Check for a few minutes at idle speed.

Maintenance work on the angle grinder will not take much time; timely preventative maintenance will delay costly repairs.

The grinder is warming itself. We find out the reason and repair it ourselves.

Bearing wear (Lepse)

In the following video, the author completely disassembles a Lepse brand grinder made in Russia (electrical machine-building plant in Kirov) in order to determine the absence of spindle rotation with a normally operating electric motor. In this case, a complete analysis of all disassembled parts is performed. Even high-quality Soviet bearings after 10 years of operation have slight wear, determined manually by the amount of play. For a detailed description of actions in such cases, see the article at the link “Replacing bearings in an angle grinder gearbox.” In the case of the Lepse model grinder, play in the front rotor bearing requires replacing it. After replacing a defective bearing with a new one, it must be lubricated, just like all other bearings of the angle grinder.

READ What can be made from a broken grinder

How to change

The presented video describes the complete technological process of disassembling, identifying defective parts, replacing them and subsequent assembly of the Makita model angle grinder. This technology contains general repair principles for angle grinders of any model. When disassembling the gearbox, damage to the housing was discovered, making normal operation impossible. by replacing it with new housing with an installed fixing mechanism. In addition, worn brushes were replaced.

Backlash (CROWN, Bosch)

Increased play not only of the rotor, but also of the spindle can cause an emergency.

grinder from the following video had increased spindle play. The author drew attention to the strong end runout of the working tool. Working in such conditions can lead to the destruction of, for example, a cutting wheel, which will create an unsafe situation for the person working with the angle grinder and the people around him. The author replaced the bearing using a puller.

In the next video, the spindle play is noticeably larger. This is due to the wear of both bearing units - the ball bearing located in the housing cover and the plain bearing located in the gear housing. Lack of lubrication - this is the conclusion the author draws by analyzing the defects. It should be noted the method by which the plain bearing is removed from the housing. A calibrated rod (in this case, a drill guide) creates pressure on the grease, which tightly fills the cavity of the inner diameter of the sliding sleeve. After loading, the lubricant penetrates into the gap between the bushing and the body and squeezes the bushing out of the seat.

By analogy with the previous two, in the next video there is spindle play in a Bosch model angle grinder. This shows that no special tool is required to eliminate the defect. It is possible to remove and replace rolling and sliding bearings without the use of pullers; only available means are used, including a latch that matches the diameter.

Why won't the grinder turn on?

Most angle grinder problems are related to the electrical part. The tool may not turn on for the following reasons:

• the cable is damaged or the plug is faulty;
• the start button is faulty;
• severe wear of the brushes or lack of contact between them and the cable;
• failure of the rotor or stator windings is the most serious reason why the “ grinder ” does not start.

It is advisable to solve problems with an electric motor in a specialized workshop that employs qualified specialists and has modern diagnostic equipment and repair tools.

Stages of the lubrication process

Lubrication can be done in special workshops or independently. When performing lubrication on your own, you must remember that a lubricant that does not match the brand of the tool can cause tool failure. The process of processing with new lubricants implies the complete removal of the old lubricant layer. The parts and walls of the housing must not contain remnants of the old coating.

Stages of lubrication of an angle machine gearbox:

• disassemble the grinder;
• wash the sides and cavities of the gearbox with kerosene or a solution of kerosene and gasoline;
• dry the washed parts;
• mix new lubricant;
• coat bearings and cavities;
• assemble the tool.

When applying, the question arises: how much lubrication is required? Applying a large amount of lubricant will cause excess volume to leak out during operation. If the content is low, the operation of the gearbox will be difficult and will lead to rapid failure. Consequently, such a volume of material is placed in the housing that the gear teeth are hidden under the surface of the applied layer. The approximate coverage of angle grinder gearboxes is less than ½ the volume of the entire gearbox.

The main malfunctions of an angle grinder and their causes

According to statistics, most cases of angle grinder failure are associated with the electrical part of the device. Some damage may be minor, which allows you to repair the angle grinder yourself. But, for example, if the motor windings burn out, only a specialist can repair an angle grinder.

Grinder won't turn on

The reasons that the angle grinder does not turn on may be the following:

• the electrical plug is faulty;
• the electrical cable is faulty;
• the start button is broken;
• the contact between the power cable and the button is broken;
• break in the contact wire of the electric brush;
• severe wear of electric brushes;
• failure of the rotor or stator windings.

The angle grinder does not develop speed

The reasons why the angle grinder does not gain momentum can be different.

1. Damage to the speed control unit. To check this version, you need to connect the device’s motor directly, bypassing the regulator, and check the operation of the device.
2. Failure of the electrical cable due to constant kinks or mechanical damage. Because of this, the damaged wire begins to heat up under load, and engine speed drops.
3. Collector contamination with dust. Contaminants must be removed with alcohol.
4. Problems with brushes. They may be worn out or have a short contact wire as shown in the following photo.

Although the brush is half worn out, it is still fully functional. In this case, a short contact wire prevents the spring from pressing the electrode to the collector. This situation may also be the reason why the angle grinder stopped working normally.

Bulgarian sparkles

If you notice strong sparking when you turn on the angle grinder in the place where the collector is located, then the reasons for this trouble may be the following.

Damage to the armature winding: break of one or more sections of the winding, interturn short circuit. With such breakdowns, increased noise appears, engine speed drops and brushes burn.

The grinder smokes and heats up

Any power tool can fail over time. This usually happens due to violation of the rules of its operation. The Bulgarian is no exception . If you have such a problem, do not panic and immediately call a technician, because in most cases you can fix the problem yourself.

To do this, you need to know the basics of electrical engineering and understand a little about the design of grinding machines. Next we will look at how to repair an angle grinder with your own hands.

Spindle lock button

If the button falls off, then you cannot use such an angle grinder.

Since the spindle can spontaneously fall onto the gear and block it during operation.

The fixation block consists of a spindle with a rubber ring, a spring and a plastic button.

• To replace the button, disassemble the gearbox .
• Remove the spindle from the housing.
• Place the spring on the button from the inside.
• Insert the spindle into the gear housing from the inside and the button from the outside. Press until you hear a click.
• Assemble the gearbox.

DEWALT D28136 why the gearbox gets hot / which angle grinder to buy review

How to determine if an angle grinder's armature is faulty

Signs of a broken armature angle grinder are: increased sparking of the brushes on the motor commutator, vibration of the motor at low speeds, rotation of the working shaft in different directions. If such symptoms are present, you should stop using the tool - this is dangerous. Suspicions can be easily verified using simple tests.

Visual inspection from outside

Troubleshooting should begin with a visual inspection of the angle grinder:

1. Carry out a general inspection of the instrument.
2. Pay attention to the integrity of the power cord and the presence of voltage in the outlet.
3. Using a voltage indicator, make sure that current is flowing to the motor commutator and the start button.

Inspection of the device from the inside

If everything is in order with the power supply, but the angle grinder does not work, you will have to open the case to gain access to the motor. As a rule, disassembly is not difficult. But you need to follow simple rules that will help you avoid troubles during reassembly:

1. Be sure to disconnect the device from the mains before disassembling.
2. Remove the working disk and protective cover from the spindle.
3. Open the case in a well-lit place, on a clean table surface.
4. Remember the location of all parts and assemblies before disassembling. It is recommended to sketch or photograph the internal structure of the device.
5. Place screws and fastening screws in a separate place so that they do not get lost.

How to extend the service life of an angle grinder

If you follow all the rules and recommendations when working with an angle grinder, you can be sure that such a power tool will last much longer than its warranty period.

During the Soviet era, angle grinders were made in Bulgaria. Therefore, the angle grinder began to be called the grinder. Currently, there are many companies producing angle grinders of various models. But the basic elements are the same. After familiarizing yourself with the device, possible breakdowns and diagnostics of the tool, you can repair an angle grinder of any modification with your own hands.

Construction and purpose of the grinder

The grinder is designed for grinding and cutting various materials. Basic elements of an angle grinder An angle grinder consists of the following elements:

1. The flat aluminum alloy gear housing allows for better heat dissipation.
2. Carbon brushes.
3. Handle attachment.
4. Electronic soft start system. Prevents jerking when turning on and reduces starting loads on the engine.
5. Quick-release protective cover.
6. Ball bearings.
7. Electric motor.
8. Grinder switch.

We offer a large selection of bearing products –

Getting high-quality lubricant with your own hands

If you want to use a good lubricant composition for an angle grinder gearbox, but there is no possibility of purchasing it, then you should make it yourself using lubricant for CV joints. Do not forget that the material used must have good adhesion.

The composition must adhere firmly to the rubbing elements. The composition for CV joints is characterized by increased adhesion and the ability to work at high temperature loads.

To prepare the mixture, a composition for the CV joint and MS-20 oil are taken to enhance the required viscosity and density. Using a homemade mixer, the composition is mixed with a small supply of oil (drop by drop).

You can also obtain material from a mixture of lubricants Tsiatim-221 and TAD-17. The main component is Tsiatim.

Mechanical breakdowns and their elimination

Mechanical failures of angle grinders include the following.

1. Worn motor armature bearings. Typically, when the bearings wear out, you may experience strong vibration while the machine is operating. In addition, grinding and other noises may be heard. Sooner or later, the bearing will collapse, and the spilled balls will fall on the gears of the gearbox. If this happens, then in addition to the bearing, the gears will also have to be replaced. Of course, it is better not to wait for this problem, but to replace it at the first sign of bearing failure. How to get to this part of the angle grinder was described above.
2. Worn ball bearing or plain bearing of the gearbox. As in the previous case, when you turn on the device, vibration will be felt and noise will be heard that is unusual for the normal operation of an angle grinder. To prevent further damage to the gearbox, it is necessary to replace the faulty part.
3. Reducer gear wear. Gears wear out quickly due to insufficient lubrication. For the same reason, the gearbox heats up. It is necessary to monitor the condition of the lubricant inside the gearbox and change it if necessary. How to disassemble the gearbox was described above. You need to use lubricant specially designed for angle grinder gearboxes, and you can buy it at points where this tool is sold. If for any reason the teeth of at least one gear are broken, then the entire set of gears (a pair) needs to be replaced.

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Industrial gearboxes are one of the most commonly used equipment. However, their active use can lead to wear of parts and subsequently disrupt the technical characteristics of the unit. The main signs of problems with the gearbox are extraneous noise, vibration, oil leakage, heating or freezing of the housing. How to fix all problems with minimal costs?

If, when inspecting the gearbox, we noticed that oil is leaking from it, the input shaft does not rotate, and it itself makes sounds that are unusual for it - this is a clear sign of problems. We identify the 6 most common root causes of gearbox problems and offer methods to combat them.

In what cases can you save an anchor and restore it yourself?

If damage to the armature is determined with guaranteed accuracy, the part must be removed from the electric motor. Disassembling the motor must be done with special care, after removing the brushes and disconnecting the power terminals. The rotor is removed along with the support bearings and the motor cooling impeller; they form a single whole with it.

If most of the wiring in the armature is damaged and the balancing is disrupted as a result of overheating, it is better to replace it entirely. An imbalance is indicated by increased vibration and an uneven hum when the mechanism operates.

How to rewind an anchor - step-by-step instructions

If the balancing of the armature is not disturbed, and the problem is only in damaged windings, then such an armature can be restored independently by rewinding the coils. Rewinding a rotor at home requires a lot of patience and accuracy.

The technician must have skills in working with a soldering iron and instruments for diagnosing electrical circuits. If you are unsure of your abilities, it is better to take the engine to a workshop for repairs or replace the entire armature yourself.

To rewind the anchor yourself you will need:

• wire for a new winding. A copper core with a diameter exactly matching the old conductor is used;
• dielectric paper for insulating the winding from the core;
• varnish for filling coils;
• soldering iron with tin-lead solder and rosin.

Before rewinding, it is important to count the number of turns of wire in the winding and wind the same amount of new conductor onto the coils.

The rewinding process consists of the following steps:

1. Dismantling old windings. They must be carefully removed without damaging the metal body of the armature. If any burrs or damage are found on the body, they must be smoothed out with a file or sanded with emery. Sometimes, to completely clean the body of slag, craftsmen prefer to burn it with a torch.
2. Preparing the collector for connecting a new wire. There is no need to remove the manifold. You should inspect the lamellas and measure the resistance of the contacts in relation to the housing with a megger or multimeter. It should be no more than 0.25 MOhm.
3. Removing old wiring on the manifold. Carefully remove the remaining wires and cut grooves in the contacts. In the future, the ends of the coil wires will be inserted into the grooves.
4. Installation of sleeves for anchors. The sleeves are made of dielectric material 0.3 mm thick, for example, electrical cardboard. Cut a certain number of sleeves and insert them into the grooves of the cleaned anchor.
5. Rewinding reels. The end of the new conductor is soldered to the end of the lamella and wound in successive circular movements, counterclockwise. This laying is called “laying to the right.” Winding Repeat for all coils. Near the collector, tie the wires together with a thick thread of cotton fabric (it is prohibited to use nylon, as it melts when heated).
6. Checking the winding quality. After laying all the windings, check with a multimeter for the absence of interturn short circuits and possible breaks.
7. Finishing processing. Treat the finished coil with varnish or epoxy resin to secure the winding. In factory conditions, the impregnation is dried in special ovens. You can do this at home in the oven. As an option, use quick-drying varnishes for impregnation, applying the coating in several layers.

How to disassemble an angle grinder gearbox correctly, video

There are many companies specializing in the production of angle grinders. The basic design principles of angle grinders for all companies are practically the same. However, there are some features that should be taken into account when repairing angle grinders of a certain brand. The experience of such repairs is presented by craftsmen in video formats, it is presented below.

Hitachi

The following video describes in detail the process of disassembling the gearbox spindle of an angle grinder of one of the Hitachi models. This is caused by replacing a stuck bearing located in the gear housing cover. In order to get to it, you must remove the driven gear pressed onto the shaft. Due to the small distance between the gear and the gearbox cover, the puller jaws are modified by grinding their surface to the required thickness in order to fit into this gap. Important: before pressing out the gear, you must remove the retaining ring that secures it.

The gearbox is broken, causes and common malfunctions

Increased vibration, the presence of an uncharacteristic sound during operation, strong heating of the case, jamming of the gearbox during operation of the angle grinder require immediate intervention to determine the causes of the appearance of these factors and eliminate them. As the practice of operating angle grinders shows, the most common gearbox malfunctions are caused by the following reasons:

• wear of bearings with the appearance of critical play;
• bearings can, as they say, “crumble” due to shock loads during “hard” operation of the angle grinder;
• increased wear of a bevel gear pair, tooth breakage;
• untimely replacement of the gearbox lubricant or the presence of low-quality lubricant in it.

Bearing wear (Lepse)

In the following video, the author is made in Russia (electrical machine-building plant in Kirov) in order to determine the absence of spindle rotation with a normally operating electric motor. At the same time, even high-quality Soviet bearings after 10 years of operation have slight wear, determined manually by the amount of play. A detailed description of actions in such cases is in the article at the link “”. In the case of the Lepse model grinder, play in the front rotor bearing requires replacing it. After replacing the defective bearing with a new one, it is the same as all other bearings of the angle grinder.

Lack of gear clutch (Interskol), gearbox is noisy/clatters

When the Interskol model grinder is operating in the next video, there is a rattling noise , characteristic of a gear pair failure. The assumption was confirmed after opening the gearbox housing, where a breakdown of the drive small gear . Further disassembly of the angle grinder made it possible to determine the probable cause of the gear failure. Increased play in the front rotor bearing could cause increased forces in a pair of bevel gears, which led to failure of one of them.
Important: increased runout of the rotor, due to a malfunction of the bearing units, can lead to the armature touching the stator winding, which will lead to an interturn short circuit and burnout of the winding. Eliminating such a defect will be quite expensive.

Popular brands of lubricants

gearbox lubricants are much more expensive than domestic ones. The Bosch brand is widely known among foreign brands. It is used to lubricate tools of the same brand, as well as other models of grinders. The coating has good performance qualities.

Among domestic manufacturers, products called “Metal Plaque Electra” are known. Lubricants of this brand are used for many components of electric tools.

READ Grilling Walls for Wiring with a Grinder

Operating an angle grinder without a lubricant coating will first lead to minor operational problems and then to failure of the tool. Lubricated gearboxes will extend the life of the tool and increase productivity. The master himself decides which lubricant is suitable for the existing device.

Do-it-yourself repair of grinder gearboxes

Should the gearbox of a new angle grinder heat up?

Grinder gearboxes operate under increased loads, so the housing of even new gearboxes heats up. However, in the presence of high-quality lubrication and the absence of technical malfunctions, the body temperature should not exceed the standard values ​​​​presented in the technical documentation attached to the angle grinder. Usually it should be around 40°C.

What to lubricate: CV joint and other options

The best option for lubricating the gearbox is a brand from the manufacturer of the grinder itself. This lubricant is tested on the manufacturer's models, so it is best suited for use. The main disadvantage is its high cost.

Lubricant for Makita , 30 grams. Photo

Users of grinders find options based on domestic oils, which are somewhat worse than branded ones, but much cheaper. CV joint lubricant has good adhesion. If we take it as a basis and add MS-20 liquid oil to obtain the desired consistency, then the use of such a lubricant in an angle grinder is fully consistent with the operating conditions of a bevel gear pair. More information about lubrication of grinder gearboxes can be found in the article at the link.

Sources:

https:///kuznechnoe-delo/kak-razobrat-reduktor-bolgarki/ https:///reduktor/pochemu-greetsya-reduktor-bolgarki.html https:///kuznechnoe-delo/remont-reduktorov-bolgarok-svoimi- rukami/

How to reduce the heating of an angle grinder gearbox / needle instead of a bushing

Due to the work being performed, when the appearance of stone, wood and iron dust is inevitable, as well as its entry into the body of the angle grinder and settling on the moving mechanical parts of the gearbox, the angle grinder needs repeated preventive inspection and boils down to the following actions:

• Removing dust and larger pieces of debris from the gearbox housing;
• Checking the presence of grease in the bearings on the gears, in addition to the integrity of the graphite brushes and changing them as needed.

Based on the circumstances that an angle grinder is a resourceful, massive piece of equipment that gets very hot during operation, the question of what kind of lubricant to use for the angle grinder gearbox is very important. We would like to immediately highlight the types of lubricants, the use of which for the gearbox (bearings and gears) of an angle grinder is not recommended by specialists. This:

Silicone, pigment and lithium lubricants and derivative materials based on them, produced in Russia and imported, have proven themselves to be excellent.

When choosing which lubricant to lubricate the gearbox of an angle grinder, it is worth listening to the worldview of experts in their repair, or simply called long-time users of this tool. Although their ideas will be far from unambiguous.

Thus, CV joint lubricants, widely known among car owners, are equally strongly both recommended and rejected by specialists. At the same time, both states give quite convincing reasons for and against the introduction of CV joints.

We can definitely say that the lubricant for the gearbox of an angle grinder must meet the following requirements:

• Be heat-resistant and not even leak from the gearbox during its heating;
• Increase gliding;
• Reduce the friction force between contacting and moving elements of parts;
• Moderately redistribute the thermal load, immediately performing cooling functions;
• Protect iron parts from corrosion, dirt and dust from penetrating into the mechanism.

How to disassemble an angle grinder for diagnostics

In order to diagnose the electrical part of the angle grinder, as well as eliminate mechanical breakdowns of the device, you will need to disassemble it. Disassembly is carried out according to the following algorithm.

1. Using a wrench, remove the disk or other attachment from the spindle of the unit.

2. Unscrew the handle.

3. Remove the protective cover.

4. Open the special windows located on the sides of the angle grinder casing and remove the electric brushes, having first disconnected the terminals.

5. Unscrew the gear housing from the angle grinder motor housing.

6. Pull the gear housing lightly and remove it from the housing. In this case, the gear unit will be removed along with the rotor.

• After removing the armature, the motor stator will remain in the casing, which can also be easily removed for diagnostics after unscrewing the fasteners.

• To disassemble the gearbox, unscrew the screws holding the cover. After removing the cover, you will see the gears of the gearbox.

• To remove the anchor from the angle grinder, you will need to unscrew the nut located inside the gearbox.

• In order to remove the bearing from the armature, it is recommended to use a special puller. Otherwise, the shaft may be damaged.

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Why does the gearbox get hot?

You can accurately determine the heating of the gearbox using a special thermal imager; if you don’t have one, you can determine the heating by touch.

The root causes of gearbox heating may be:

READ Is it possible to cut glass with a grinder?

Gearbox surfaces must be clean

Why is oil leaking?

If you find traces of oil on or around the gearbox, we advise you to immediately inspect the gearbox and take all necessary actions. Oil can flow through the seals and along the plane of contact of the bearing caps to the housing or through the seals. To solve the problem you will need:

Drive power and size

Grinding machines have different sizes and wheel diameters. The minimum size is equivalent to 115 mm. This wheel is designed for easier work. The largest size is considered to be 230 mm in diameter. With this wheel you can cut bricks, slabs, pipes and anything else you need. A diameter of 125 mm will be considered the optimal choice for a circle for homework. To renovate a house or apartment, you need to choose a circle equal to 180 mm. The power of the tool varies from 0.5 to 2.5 kW.

The choice of this parameter depends on the operating time and engine power. There must be enough engine power to move the disk.