DIY repair drill

The hammer drill is only capable of performing conventional drilling with a hammer. The gearbox of such devices can have either one or two speeds. As additional functions, there are reverse travel and the ability to adjust the desired idle speed.

An impact drill has two helical gears that make contact during normal drill operation. When hammer drilling is required, one gear moves, thus creating a gap with the gear in front. Further, the rear gear remains stationary, and the one in front begins to slide along the teeth and move the cartridge up and down. This is how the impact is created with many impact drills. Moreover, the number of such blows can be 40,000 per minute.

It should be noted that the impact function of the drill should be used only in the most urgent cases. If the drill is constantly used with the impact function, then very soon the impact mechanism may fail. It's all about the gears, which sooner or later grind off and the shock mode of operation will disappear.

Electric drill device:

A tool such as a hammer drill is an indispensable tool in construction. For example, she can drill through a brick without any problem. As for concrete, the performance of a hammer drill depends on the grade of concrete in which you want to drill a hole.

Let's say with a 300 grade of concrete, from which internal partitions of premises are usually erected, an impact drill does an excellent job. But this cannot be said about the 400th grade of concrete, which is used in the construction of load-bearing walls. In this case, it is necessary to use a puncher.

An electric drill is the most demanded electric tool for any repair, so it often fails due to frequent and intensive use. If you have basic skills and experience in repairing such tools, it will not be difficult to repair a drill.

Possible hammer drill malfunctions

There may be several reasons for breakdowns of this kind of tool, there is an opinion that the main reason is improper operation of the drill or the lack of firmness of the tool, which is why its insides consist of low-quality components. Other more technical reasons include:

Failure of the moving part of the electric motor, its stator or armature;

Failure of bearings;

Breakage of the button (speed controller);

Reversing switch breakage;

The wear of the collector brushes and their burning;

Broken wire in the cord, in the drill itself or on the motor coil itself;

Damage to the gearbox or self-chuck.

How to find the fault

In order to understand the reason for the breakdown, sometimes it happens that it is not immediately visible, for example, the drill simply does not rotate. Inspection begins with the power cord, often due to intensive use, the cord is interrupted either in the area of ​​the plug or somewhere else. Also inspect the button and various controls. Trying to crank the cartridge.

This completes all the diagnostic procedures, the drill needs to be disassembled in order to gain access and inspect it from the inside. To do this, unscrew (all) the screws around the perimeter of the drill body and remove the upper half of the body. When unscrewing the screws, pay attention to their length and remember in which hole the screws of what length were, it is easier to leave them immediately in the removed part of the case.

We inspect the power cable and internal wiring for burns, breaks and the reliability of the contact connection.In the place where the power cable enters the drill body, you can often see a damaged outer layer of insulation, its break, and the power cable itself is ultimately twisted.

If you have a faulty button or reverse switch, it is easier to replace it with a new one. You can, of course, disassemble, clean the contacts, but it will be troublesome to assemble, there are many small parts and springs that everyone strives to jump out.

One of the most common types of damage is the wear of the engine brushes, they can be easily replaced at home. Sometimes, the brushes can be replaced without disassembling the drill body, if the design allows it.

For some models, it is enough to unscrew the plugs from the installation windows and install new brushes. For other models, disassembly of the body is required for replacement, in this case it is necessary to carefully remove the brush holders and remove the worn brushes from them.

A typical symptom of a malfunction of electric brushes is strong arcing and unstable operation of the electric motor when it works intermittently or jerky. Which comes from the intermittent electrical contact between the brushes and the plates on the manifold.

You should also not allow the brushes to wear out to a minimum size. This is dangerous because the gap between the brush and the collector plates can increase. As a result, increased sparking occurs, the collector plates get very hot and can "move away" from the base of the collector, which will lead to the need to replace the armature.

It is necessary to regularly clean the collector plates from carbon deposits and constantly check the tension of the brushes to the collector drum. Other malfunctions of the electrical part can manifest itself in the form of a lack of rotation of the drill motor, when there is no sign of the motor turning on (no buzzing is heard).

If the drill does not turn on and its chuck is easily rotated with the usual effort, then we can most likely assume that the electrical part is faulty.

Checking the specificity of the reason is carried out as soon as it becomes available, the power cord, the speed control button, the starting capacitor and the motor windings are checked, everything is simply ringed out with a multimeter in resistance mode.

Among the electrical faults, an anchor breakage can be noted. Breakage of the armature or stator occurs for two reasons - improper operation and poor-quality winding wire. Top world-famous manufacturers use high-quality double-insulated wire with heat-resistant varnish, which significantly increases the reliability of the motors and significantly extends the life of your drill. Cheap models do not withstand prolonged and intense robots with overheating.

A breakdown of the armature (malfunction of the coils) can be diagnosed by a characteristic smell, an increase in sparking during operation. And upon examination, you can see the burnt windings of the wire. But you can also observe a drop in engine power, which will indicate that the windings have begun to burn, their resistance has already changed from this, which can be seen with a tester.

You can observe the following breakdowns of the armature and stator: turn-to-turn electrical breakdown, breakdown to the “case” (magnetic circuit) and winding breakdown. Breakdown to the case can be determined using a megohmmeter (multimeter) by touching the probes to any output of the winding and the magnetic circuit. Resistance over 500MΩ indicates no breakdown.

You should know that, ideally, measurements should be done with a professional megohmmeter, which has a measuring voltage of at least 100 volts. Making measurements with a simple multimeter, it is impossible to accurately determine that there is definitely no breakdown, however, it can be determined that there is definitely a breakdown. Another breakdown can be measured by a simple method, using a light bulb connected with one terminal to a 220 volt network, and the second terminals to the body and collector plates.

It will be a little more difficult to determine the interturn breakdown of the anchor.To do this, you can use a special transformer, which has only a primary winding and a rupture of the magnetic circuit in the form of a trough, to install an armature in it. In this case, the armature with its core becomes the secondary winding.

Turning the armature, so that the windings are in operation one by one, we apply a thin metal plate to the armature core. If the winding is short-circuited, then the plate begins to rattle strongly, while the winding heats up noticeably.

Often the turn-to-turn closure can be seen during normal inspection, the turns can be bent, crumpled. You can try to fix it yourself by bending to the sides the closed or bent turns of the wire.

To find a break in the armature winding, you can connect a milliammeter to the adjacent armature plates and slowly turn the armature. In whole windings, a certain identical current will appear, an interrupted one will show either an increase in current or its complete absence.

Using the comparison method, you can find the faulty one or make sure it is working properly if all the windings give the same values ​​on the multimeter.

A break in the stator windings is determined by connecting an ohmmeter to the disconnected ends of the windings, the absence of resistance indicates a complete break. In this case, it is impossible to make repairs with your own hands, rewinding the armature or stator, without special devices.

When rewinding the windings, it is necessary to fulfill the conditions: the windings are wound in one direction, the beginning of the winding is marked at the coil, the wire is wound clockwise, after which the end of the terminal is marked. The second winding is wound in the same direction, with the marking of the terminals beginning and end.

To replace the rotor or stator, it is necessary to disassemble the housing, disconnect the wires, brushes, if necessary, remove the drive gear, and remove the entire motor together with the support bearings. Buy a replacement and put everything back in.

If you suspect a button breakage (speed controller), you must make sure that there is voltage at the input and output terminals of the button. If, when you press the button, the output voltage does not appear, you need to disassemble the button body and inspect all the contacts.

As a rule, burning or sticking of contacts is determined visually. All contacts must be thoroughly wiped with alcohol and cleaned with sanding paper. Then check the voltage again. Do-it-yourself button repair is possible only if you have certain skills.

It is important to understand that after opening the case, many switching parts will simply fall out of the case. This can only be prevented by smooth and accurate lifting of the lid initially.

When replacing a button with a new one, you need to make sure that the new button is rated for the power of the specific drill. For example, for a 750 watt drill, the regulator must be at least 3.4 amperes.

Impact drill button connection diagram:

The reversible pushbutton is tested in the same manner sequentially. The reverse mechanism is based on a make and break contact system. Its prevention is carried out in the same way as the start button.

Connection diagram of the speed control button and the reverse of the hammer drill:

Failure of the starting capacitor can also become the reason for the “non-operation” of the electric motor. Usually, a non-working condition of a capacitor can be seen by a color change. But it is more reliable to measure its capacity and compare it with the nominal value.

Repair of the mechanical part of the drill

In the mechanical part of the hammer drill, there may also be various breakdowns, for example, a jammed drill shaft. If the chuck cannot be turned by hand, and the engine hums when turned on, then the reason is most likely a breakdown of the gearbox or bearings. A common cause of failure can be seen in the destruction of journal bearings.

A breakdown of the gearbox can also appear in the case when the chuck is turned by hand and the electric motor is running, and the rotation is not transmitted to the main shaft.All faults in the mechanical part can cause intermittent stops and malfunctions during operation, hum, grinding and insufficient shaft rotation speed.

The principle of the hammer drill is based on the translational movement of two ratchets, which repel each other as the motor spindle rotates. During hammer drilling, the motor drives the spindle.

From the spindle of the engine, the rotational movements are transmitted further to the large gear of the gearbox to which the ratchet is rigidly attached.

Scheme of a "planetary" gearbox:

The wavy surface of the ratchet of the large gear slides over the wavy surface of the second ratchet rigidly fixed to the gear housing, thereby performing impact actions.

Over time, in the process of prolonged and intensive use of the drill in the drilling mode with an impact, the wavy surfaces of the ratchets wear out, the impact becomes weaker and weaker, or does not occur at all. It is necessary to inspect the worn parts of the gearbox and, if necessary, replace with new ones.

If the chuck is jammed or an audible grinding noise, first of all, you need to disassemble the drill body and inspect the condition of the gears in the gearbox. The wear of the mounting splines or the destroyed teeth of the gears indicate the failure of the part. This gear must be replaced.

The gears are inspected along the entire circumference, smoothly turning the shafts by hand. The bearings can be checked by turning the shaft in them. If the shaft is sluggish, start by lubricating the bearings. If this does not help, then they are removed from the axle using a special puller.

The bearing cage is scrolled by hands. If movement is difficult or extraneous sounds are heard, then the bearing should be replaced. A bearing not replaced in time will lead to jamming of the armature, or, in the best cases, the bearing will simply turn in the seat.

To get to the bearings of the drill, it is necessary to completely remove the motor together with the gearbox, after removing the brushes so that they do not break and so that they do not pop out.

Before taking out the insides of the drill, carefully consider what, where it was, so that during assembly, as is often the case with “experienced” craftsmen, a bunch of unnecessary elements are not left, which are difficult to use. Do not lose the ball, which is at the end of the drill chuck shaft, it is responsible for drilling with and without impact.

If necessary and if the drill chuck is severely worn, unscrew the fixing screw, which is located inside the chuck. After that, the chuck with the left-hand thread is unscrewed and removed from the shaft. The cartridge is replaced with a new one.

Often, the drill breaks down during serious work, during an ongoing repair or in other conditions, so as not to waste time and so that this is not a problem for you, you should remember how to repair the drill yourself. You should know the design of the drill used and easily and quickly determine the cause of the malfunction and eliminate it.

The drill is considered one of the most popular DIY tools and is used in many types of work. Due to heavy use, tool parts can break and damage the device. Do not rush to the service center: it is quite possible to repair the drill with your own hands and save a lot of money.

If you know the device of the drill and the principle of operation of the tool, then self-repair of the product will not complicate you.

Regardless of the model or manufacturer, all of these electrical tools consist of a typical set of basic components.

Any do-it-yourself drill repair must begin with a visual inspection of all parts. The principle here is simple - from simple to complex, that is, first we check the cord, wiring, contacts, various fasteners, then we start testing the blocks and the engine.It does not always come to a complete disassembly of the product, but in practice you need to be prepared for such a development of events. How to disassemble a specific model, the instruction manual will help.

Regardless of the build quality and manufacturer, the following malfunctions occur quite often:

• the electric motor fails due to a breakdown of the armature or stator;
• extreme wear of brushes;
• bearing problems;
• the speed control button does not work;
• the contacts of the start button are oxidized or burned out;
• breakage of the chuck holding the drill due to wear of the jaws.

If you decide to repair an electric drill yourself, then first you need to diagnose and find a malfunction. It is rarely possible to repair a failed part on its own, as a rule, it is simply replaced with a new one.

Before disassembling the drill, make sure it is disconnected from the mains. Any disassembly begins with the removal of the fasteners. Then we unscrew the screws and self-tapping screws, remove the upper part of the product - all the components remain in the lower part. Drill wiring diagram quite simple - there is no need to separately describe all the elements, everything is already intuitive.

Naturally, it is much more difficult for models with electronic adjustments, but it is hardly possible to repair a drill with such units on your own, it is better to entrust this to specialists from the service center.

When the power goes out, you just need to change the position of the product - the reason lies in the cable, most likely one of the wires broke... It is necessary to disconnect the drill from the mains and check with a multimeter cable. You can use the simplest option - a light bulb and a battery in the same circuit.

Attention! Pulling the cord when the drill is plugged in is strictly prohibited, in order to avoid a short circuit - you will have to rewind the motor winding.

After checking, you can bend it as you like so that find the place of the cliff, then a part of the cable is cut off, the wires are stripped and new contacts are created for connection. When a break occurs in the middle of the cable, then it must be completely replaced with a new one. True, thrifty users prefer to connect broken wires by soldering, followed by reliable isolation of the repair site, but there is no longer complete trust in such a wire.

This part has a very simple design, but if a problem occurs, it will prevent the drill from starting. Its work is simple: the key slides in a special block and closes the contacts with a pusher finger. From long-term operation inside the block dust accumulates, which prevents the button from moving and blocks it, preventing the contact circuit from closing. The defect is easily eliminated - open and remove dust with a brush.

Important! Never try to lubricate the sliding surfaces of the button - the dust will mix with the grease and deplete, resulting in the entire unit being replaced.

To repair the drill button, you need to remove the side wall, check the integrity of the contacts. When carbon deposits have formed, clean the contact with fine sandpaper. If the contact burns out, we change the entire block.

Not all users know that power from the mains is transmitted to the rotor using brushes made of graphite - during normal operation, constant arcing occurs between them and the rotor. There are times when a wad of dust is crammed between the armature and the brush, and since the dust is a dielectric, the drill will not work until we remove the dust and restore contact.

During use, the brushes gradually decrease, because their lower part is erased. Periodically they need to be inspected and changed - it's easy to do, you just need to have a new set in stock.

When you notice strong sparking in the area of ​​\ u200b \ u200bthe brushes, and have recently changed them, this can happen due to rotor problems or its manifold.

For a thorough check, carefully remove the rotor from the stator.Contacts can be charred or have scale - you need to clean them with sandpaper strictly in the direction of rotation. The reason the appearance of dross there can be long-term work at maximum speed. How to check if the rotor is working properly? Ring the adjacent lamellas with a multimeter - their resistance should be identical.

Do not forget check winding - whether there was a short circuit with the magnetic circuit case. In the event of a breakdown, the faulty winding is rewound independently or taken to a service center.

A visual inspection must be done periodically: in case of overheating, when the product was operated at maximum loads, the protective varnish could melt and occur turn-to-turn closure... In this case, the winding will burn out, and the electric motor is unsuitable for further operation. The check is done in the same way as in the case of the rotor - we check the windings with a multimeter. If a breakdown is detected, the stator winding must be rewound.

Leading manufacturers of impact drills pay special attention to the protection of the winding wires, because their products operate in a special mode.

Why is the device still not working if you checked everything and ruled out breakdowns in the electric circuit of the drill? There can be only one answer - the non-working state of the product arose due to the presence of mechanical faults.

1. Bearings do not work... Dust gets into the grease due to the breakthrough of the stuffing box, so they wear out quickly and can jam at some point. It is easy to eliminate: we wash the bearing in kerosene, change the oil seals, fill in new grease, better than a special composition for products with high rotational speeds.
2. Broken reducer - a very serious breakdown, you need spare gears, or you will have to replace the entire module. It is only necessary to install the same model. If the drill is a common modification, then it is not a problem to buy spare parts for it in stores.
3. Experts consider one of the most difficult malfunctions breakage of cartridge parts.

During work, drilling waste often gets into the inner part of the chuck, they mix with the lubricant, which wedges the inner jaws. The cartridge must be disassembled, all parts are washed and lubricated before assembly. If extreme wear is found, then the part must be replaced; if the base or sleeve is severely worn, the entire block should be replaced.

We tried to tell you about all the failures encountered during the operation of electric drills. Remember that DIY repairs are always much cheaper than buying a new product.

An electric drill in a home workshop takes a special place. Therefore, tool breakage is a big enough nuisance. Despite the complexity of the design, it is quite possible to make an independent repair.

2.button with switch-on unit - can be equipped with

reverse switch (speed regulator);

3. shaft rotation speed regulator (or reverse switch);

4.Gearbox housing - carries out load-bearing functions for rotating

5. gears and reducer mechanism;

6. bearings of the shaft of the cartridge and the armature of the engine;

8. brush assembly of the electric motor;

9. chuck with drill or cutter holding mechanism.

The drill never breaks as a whole: one of the elements fails. Having understood the design and interconnection of the power tool assemblies, it will be easier to localize the malfunction.

Drill repair is carried out according to the principle "from simple to complex". You should not immediately disassemble the tool to the screw, and assess the condition of all nodes at the same time.

• The drill does not turn on. We start with the power cord (at least before that, you should check the voltage in the outlet and extension cord). Having disassembled the case, we find the cable contacts, and "ring" them with a multimeter.

Important! Do not check the power cable with voltage applied! If the current-carrying conductors break, you can get an electric shock, or organize a short circuit.

We connect to the socket of the mains plug and the opposite terminal of the cord. Then we bend the cable several times along its entire length. Lost contact or its complete absence indicates the presence of an open circuit inside the insulation. If the fracture of the current-carrying conductor is close to the edge, the cable is cut and reconnected. It will just be a little shorter. If the gap is in the middle of the length, it is better to replace the wire. The splicing will be unsafe.

• The cord is working properly - we check the switch. We connect the multimeter to the terminals, and press the key. A large current flows through the contacts, sparking occurs (especially when dust enters the case). Contacts can corny oxidized. Carefully disassemble the switch body and clean the contact groups with fine sandpaper.

In case of breakage of metal parts, it is better to purchase a new unit.

• If there is an additional contact group in the circuit between the switch and the electric motor (for example, a reverse switch or a speed regulator), we diagnose this node as well.
• Next, we check the connecting wires from the switch to the motor brushes. If they are in order, we diagnose the brush assembly.

The springs should confidently press the brushes against the anchor lamellas; we check the carbon elements themselves for wear. If necessary, we change: spare parts are included in the delivery set, or purchased in specialized stores. The armature contact strips can be oxidized or clogged. They can be gently cleaned with fine sandpaper.

• A more complex breakdown is failure of the armature or stator windings. Using a multimeter, a short circuit is checked between the body of the unit and the contacts of the windings. Then the resistance is measured. The value should be the same on each winding, the variation in readings should be no more than 5%. Defective windings must be rewound.

• This can be done on your own, or in a repair shop (in any case, it will be cheaper than buying a new engine).

Such breakdowns manifest themselves quite clearly. Extraneous noise, grinding, shaft jamming, etc.

• The motor rotates slowly and the windings get very hot. Or, during normal rotation, a characteristic hum (grinding) is heard. Most likely - the rotor bearings are worn out or clogged. Having disassembled the drill body, we carefully take out the rotor. It is removed together with the bearings. By twisting the outer clip, you will immediately determine the malfunction. If the bearings rotate tightly, they must be flushed with a penetrating liquid (WD-40 or regular kerosene)

Important! Make sure that no liquids get into the armature winding! Otherwise, the insulating varnish may dissolve, and an inter-turn circuit will occur.

Then grease is placed between the clips for high-revving units. Lithol or graphite grease for automotive bearings will do.

If there is a backlash between the bearing races, the units must be replaced.

Dismantling is carried out with a special puller or with an open-end wrench.

If there are no balls, be sure to find them in the case. Dropped objects can get caught between engine or gearbox parts and damage the entire unit.

• The bearings of the chuck shaft are diagnosed and repaired in the same way. Only dismantling them without a puller will not work.
• If the mounting place of the outer bearing race (bed) is worn out (this happens when the bearing is jammed), you will need to make liners of thin sheet metal. Otherwise, beating will occur when the shaft rotates.
• The engine rotates in normal mode, noise and grinding noise are heard from the gearbox housing. The shaft turns unevenly. Worn or destroyed gears of the reducer.

We disassemble the case and examine the gears.

It is advisable to wash the assembly of old grease and rotate the shaft 360 °, controlling the engagement of the gears. If a backlash or excessive wear of the teeth is detected, the mechanical part will have to be changed.

Perhaps a large amount of dust has simply accumulated in the gearbox housing.Together with the lubricant, an abrasive paste is formed. In this case, after flushing the assembly, simply add new grease.

Tip: The grease should be changed periodically without waiting for breakage.

Especially if you often drill stone walls.

• The cartridge is broken. For cam devices (turnkey) this is a great rarity, the design is reliable and simple. The unit is exposed to dust, so the internal mechanism can easily jam. Most often, the gripper guides are clogged with small abrasive particles.

If the chuck does not twist well, it is enough to blow it out with compressed air and treat it with a penetrating lubricant.

Attention: The jaw chucks do not lubricate the inside!

It is quite difficult to disassemble a part without a special tool. If some component is mechanically broken inside, you still have to change the entire assembly.

But keyless chucks, on the contrary, are easily disassembled and repaired.

They are not as reliable and do not carry the load well. To disassemble such a cartridge, it is enough to remove a pair of lock washers. You will easily find a broken or worn part that can be easily replaced.

There are two types of fastening: Morse taper, and threaded. In the first case, you need to inflict several blows with a small hammer on the back of the cartridge. After which it can be easily removed.

To unscrew the threaded fastener, the shaft is held with a wrench (there are special flats on the shaft).

There are no faults that cannot be corrected by hand. If a separate unit cannot be restored, only it changes, there is no need to buy a new drill.

To prevent breakdowns, you should adhere to simple rules:

• After dusty work, blow out the ventilation holes and the interior of the cartridge. Keep the instrument clean.
• Do not overheat the engine - take breaks for prolonged use.
• Refill the grease on the rotating parts periodically.

An electric drill is one of the most common household tools. And it's very bad when it suddenly stops working. In such cases, I really want to repair the drill with my own hands.

Electric drill device diagram.

The design of a drill or hammer drill is quite simple. Different tool models mainly differ only in the difference in the arrangement of parts and the quality of their manufacture. The versatility of the operating principle and structures used allows you to make independent repair of the drill in most cases of malfunctions.

Any electric drill consists of a body, which houses the electrical and mechanical parts, and a chuck, in which the drill is mounted, on the main shaft of the drill. The electrical part usually contains:

• electric motor;
• contact brushes fixed in the brush holder;
• start button (switch);
• engine speed regulator;
• reverse device;
• starting capacitor;
• power cord (cable).

Diagram of the percussion mechanism of the drill.

In turn, a two-phase AC motor consists of a stator and a rotor (armature) with a collector.

The mechanical part includes a gearbox and a bearing system. The gearbox transfers the rotation of the electric motor to the drill shaft, reducing the rotation speed. A more complex mechanical part in a hammer drill (hammer drill). The hammer drill's reducer provides the percussion-translational and rotational movement of the drill (drill). Its design, in addition to the gear, includes pistons (shock and flying), ram and firing pin.

A malfunction of the electrical part manifests itself in the form of a lack of rotation of the engine, i.e. when there is no indication that the engine is running (hum, vibration, etc.). If the impact drill does not turn on, and the cartridge is easily turned by hand, then we can safely talk about a malfunction of the electrical part. The same can be said if there is no speed control or reverse rotation.An expected malfunction in the electrical part is indicated by sparking during the operation of the drill. Temporary interruptions in the operation of the drill, extraneous noise can also indicate an electrical circuit.

Most often, a malfunction in the electrical part is due to wear of the contact brushes. If they are cut by 40%, then sparking and malfunctions can be observed. With more wear on the brushes, the electric motor simply does not turn on. The procedure for determining the culprit of a malfunction in the electrical part is recommended as follows (as available). First, the tester determines the integrity of the cord (cable). Then the operation of the start button (switch) and the integrity of the starting capacitor are checked. Then the contact buttons are removed and checked. Finally, the integrity of the motor windings is determined.

A clear sign of a mechanical problem is a jammed drill shaft. If the cartridge cannot be rotated by hand, and at the same time the hum of the electric motor is heard when turned on, then the reason lies in the breakdown of the gearbox or bearing. The most common cause of mechanical failure is the failure of thrust bearings. A breakdown of the gearbox can also appear in the case when the chuck is turned by hand and the electric motor is running, and the rotation is not transmitted to the main shaft. A malfunction in the mechanical part can cause periodic malfunctions (temporary stoppages) of the drill, hum, grinding and insufficient shaft rotation speed. In rock drills, a malfunction in the mechanical part can remove the impact movement of the drill.

Finally, a malfunction can manifest itself in the drill chuck. So, it can be difficult to remove the drill when the cams do not open due to breakage in the engagement inside the chuck. Sometimes the malfunction manifests itself in the form of scrolling the chuck relative to the drill shaft. In this case, a malfunction occurs in the area where the chuck is attached to the shaft.

One of the most common causes of malfunction is wear or burning of contact brushes. The first signs of brush wear appear in the form of sparking in the contact area of ​​the brushes with the electric motor armature and minor malfunctions of the drill when the load is increased.

The location of the contact brushes inside the drill.

Many drill models have simplified access to the brushes, and changing them is not difficult, and some drills require disassembling the body and removing the brush holder. The brushes must be replaced with new ones equal in size to the failed brushes.

They should be firmly attached to the brush holder. The electrical contact of the lead wire must be tightened well. The contact of the brush with the armature collector must be reliable. It is necessary to check the action of the spring.

Failure of an electric motor is the second largest cause of a drill malfunction. This is due to damage to the stator winding or armature. Such damage occurs due to a factory defect in the windings or improper operation of the drill (long-term operation without interruptions, the load in excess of the permissible load when the drill is jammed, etc.). As a rule, electrical breakdown of the winding is easily identified visually or by the characteristic burning smell. If there are no visible manifestations, then the motor windings should be checked with a tester, ohmmeter and megohmmeter for the value of resistance. There may be three types of wire damage - short circuit between turns, breakdown of a turn to the body, or wire breakage. Repair of the stator or armature is not carried out independently.

Drill motor connection diagram.

To replace the elements of the electric motor, the drill body is disassembled, the contact brushes and lead wires are disconnected, and the electric motor is removed together with the support bearings.

If necessary, retract the drive gear. The faulty element of the electric motor is disconnected and replaced with a new one or the old one is installed after repair (rewinding) by professionals.

The switch (start button) and the rotational speed regulator in the drill are usually combined.The speed is regulated by pressing the button with different efforts. First, you should check the presence of voltage at the input and output terminals of the button. If there is no signal, then carefully remove the button housing and inspect all contacts. As a rule, burning or sticking of contacts is determined visually. All contacts must be thoroughly wiped with alcohol and cleaned with sanding paper. After that, the presence of voltage should be checked again. If there is no signal, the button should be replaced with a new one. The cause may be a violation of electrical contact with the wire. In this case, the wire must be soldered.

Drill button connection diagram with reverse.

The reverse rotation mechanism is based on a system of make and break contacts. Its prevention is carried out in the same way as the start button. In addition, you should check all the wires of the mechanism going to the brushes and the stator of the electric motor.

The reason for the impossibility of starting the electric motor may be the failure of the starting capacitor. Usually, a non-working condition of a capacitor is noticeable by a color change. But it is more reliable to measure its capacity and compare it with the nominal value.

Checking the electrical part begins with determining the integrity of the power cord (cable) using a tester or ohmmeter.

The resistance between the contacts of the plug is measured (determination of the short circuit of the wires) and the resistance of each core.

A jammed chuck or a grinding noise indicates a failure of the gearbox or bearings. First of all, you should disassemble the drill body and inspect the condition of the gears in the gearbox. The wear of the mounting splines or the destroyed teeth of the gears indicate the failure of the part. This gear must be replaced. The gears are inspected along the entire circumference, smoothly turning the shafts by hand.

The bearings are checked by turning the shaft in them. If the shaft is sluggish, start by lubricating the bearings. If this does not help, then they are removed from the axle using a special puller. The bearing cage is scrolled by hands. If movement is difficult or extraneous sounds are heard, then the bearing should be replaced.