Do-it-yourself repair of a cress hammer drill chuck. Do-it-yourself hammer drill repair. Mechanical faults and their elimination

Nothing lasts forever. And the most reliable Bosch rotary hammers begin to break over time. But any malfunction can be repaired with your own hands if you have detailed guide on implementation repair work. Below we offer you a guide to troubleshooting Bosch rotary hammers and a method for eliminating them.
The main causes of breakdowns are:

• careless work with the tool;
• improper storage of the hammer drill;
• heavy loads when working on working parts when chiseling or drilling;
• tool overheating;
• long work without a break;
• failure to comply with maintenance schedules.

Conventionally, faults can be divided into mechanical and electrical.

Mechanical malfunctions of the Bosch rotary hammer

When mechanical malfunctions occur in the operation of the tool, an extraneous unpleasant sound appears, sparking intensifies in the collector area, a burning smell appears, the tool heats up excessively, its power drops depending on the duration of operation and the impact on the material.

We will look at all the faults in the diagram of the Bosch 2-26 rotary hammer. Other models, such as Bosch 2-20, 2-24, install various types of bearings.

The hammer drill stops hammering, but drills

The hammer drill does not hammer under load or in idle mode for the following reasons:

• the rubber rings of the striker, striker, and piston are worn out;
• the rolling bearing race has collapsed;
• the cylinder and the barrel's firing pin were destroyed impact mechanism;
• cut off the splines of the clutch mounted on the intermediate shaft;

The hammer drill has stopped drilling, but is chiseling

The main reasons why a rotary hammer hammers but does not drill are:

• the force of the conical spring pressing the clutch has weakened;
• the locking roller does not fix the large barrel shaft gear;
• does not hold the tool locking mechanism in the barrel;
• The hammer drill does not chisel or drill.

The main reasons why a hammer drill does not chisel or drill are:

• sheared teeth on the small rotor gear or on the large intermediate shaft gear;
• The electric motor of the hammer drill does not work;
• there is no power to the hammer drill motor.

Now first things first

Let's consider options in which the hammer drill does not hammer, but drills

Wear of rubber rings on the striker, striker, piston.

This reason appears gradually as the rubber rings wear out. At first the blow weakens, then disappears altogether.

The malfunction is eliminated by replacing the indicated rubber rings with new ones.

For any repair of rotary hammers or their components, all rubber products must be replaced.

The rolling bearing race has fallen apart (drunk bearing)

If the drunk bearing pos. 830 is destroyed, the rotational movement of the intermediate shaft cannot be converted into the translational movement of the cylinder in the impact mechanism.

Eliminated by complete replacement rolling bearing.

The cylinder, firing pin, and firing pin of the firing mechanism were destroyed

There are cases when the striker in the cylinder, pos. 26, gets stuck, which leads to destruction of the cylinder and the impossibility of creating air pressure in the barrel of the striker mechanism. And the second reason: destruction or breakage of the striker pos. 28, leading to distortion of the part and the impossibility of transmitting the shock impulse.
Breakdowns are eliminated by completely replacing failed parts.

The splines of the clutch, pos. 67, mounted on the intermediate shaft, were cut off

The malfunction can be eliminated by repairing the clutch or completely replacing it.
When making repairs, the worn teeth on the clutch are filed down. To correct this defect, a round needle file and a drill are used. The coupling is clamped in the hand, and the tooth profiles are straightened using a drill with an appropriate needle file. The splines on the intermediate shaft are modified in the same way.

Let's consider options in which the hammer drills but does not chisel

The force of the conical spring pressing the clutch has weakened

When the pressure force of the spring pos. 50 decreases, the clutch slips on the intermediate shaft without transmitting rotation from the small spur gear to the large gear pos. 22 of the barrel shaft pos. 821 of the impact mechanism. By the way, on different models Bosch.

The locking roller does not secure the large barrel shaft gear

The large gear, pos. 22, is attached to the barrel shaft, pos. 01, with a roller, pos. 88, pressed against the shaft collar with a conical spring, pos. 80, and secured with a retaining ring, pos. 85.

The reason may be a weakening of the force of the conical spring pos. 80, destruction of the locking ring pos. 85, or loss of the fixing roller pos. 88.

The mechanism for fixing the tool in the drill barrel does not hold the drill

Bosch rotary hammers use two types of chucks: SDS-plus and SDS-max. The difference is in the design of the locking mechanism.

The reason is the wear of the antennae of the chuck's raster bushing, which makes it impossible to transmit the shock pulse to the working tool of the hammer drill.

Let's consider options in which the hammer drill does not drill or chisel

Sheared teeth on the small rotor gear

The gears rotate and the teeth on one of them, usually the small one, are cut off.

When the working tool jams and the clutch does not work properly, wear or complete destruction of the gear teeth on the hammer drill shaft and the intermediate shaft occurs.

In this case, the rotor or large intermediate shaft gear is completely changed.

Hammer drill motor does not work

The reasons for a non-working electric motor may be:

• short circuit in the rotor, stator;
• destruction of carbon electric brushes;
• loosening of the brush holders;
• burnout of lamellas on the rotor commutator;
• breakage of the rotor or stator windings.

The listed malfunctions are eliminated by repair (manually rewinding the windings, replacing the commutator and desoldering the winding leads) or replacing the rotor, stator, and carbon electric brushes with new ones.
The majority of malfunctions in the electrical part of the Bosch 2-26 rotary hammer are confirmed by increasing sparking in the collector area.

The length of serviceable electric brushes cannot be less than 8 mm. When replacing one brush, the second should change automatically.

The rotor or stator windings can be rewound yourself at home.

No power to the electric motor of the Bosch rotary hammer

The cause of this malfunction is a break in the wire supplying power to the electric motor. Most often, a break occurs at the point where the cable enters the hammer drill. The wire should be replaced with a new one or repaired. The malfunction can be determined using a tester. If there is no tester, the fault can be found using the power phase and a screwdriver with a neon indicator lamp. Connecting the power wires one by one, at the other end, using a neon screwdriver, determine the presence or absence of a phase.

The power button for the hammer drill does not work. Determined by a short circuit tester.

Most often, the failure of the punch button is caused by a short circuit of the filter capacitor. It is best to replace the button with a new one.

General electrical faults of the Bosch 2-26 rotary hammer

Failure of a rotary hammer in the electrical part is accompanied by the appearance of a burning smell, strong heating of the tool during operation, the appearance of large sparks in the area of ​​the rotor commutator of the rotary hammer, and poor operation of the reverse switch.

The operation of the hammer drill is influenced by the condition of the carbon brushes, the reliability of the fastening of the brush holders and their correct installation.

A burning smell appears when short circuit stator or rotor windings.

A drop in hammer power with increasing load is typical when there is a break in the rotor windings or when the carbon brushes are short.

The heating of the hammer most often results from a short interturn circuit in the stator or rotor.

Large sparking in the commutator area is caused by interturn closure of the rotor or burnout of the commutator lamellas.

Malfunction of the reverse switch occurs due to burning of its contacts.

But main reason all breakdowns, untimely implementation of technical routine maintenance and replacement of carbon brushes.

Carbon brushes require replacement after 70 hours of operation or when worn down to 8 mm in length.

We have given the main reasons why Bosch rotary hammers fail.
We may not have described all the breakdowns of Bosch rotary hammers.

If you know other faults with Bosch 2-20, 2-24, 2-26 rotary hammers, please share with us.

Good luck to you!

Video of replacing the raster bushing in the Bosch 2-26 cartridge

Video of replacing the armature in a Bosch 2-26 rotary hammer

A rotary hammer always works under difficult conditions and may fail after a while. You can buy a cheap fake again, but you can’t just throw away a branded model. In order not to pay a “round” sum for repairs, you can repair the rotary hammer yourself. But for this you need to understand what components the tool consists of, the order of its disassembly and possible replacement certain details.

TOOLS AND MATERIALS REQUIRED

Screwdrivers Tweezers Pliers

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How does a hammer drill work?

Any electromechanical device becomes unusable over time. If you have certain skills, then you can try to do the repairs yourself. To do this, you need to know the operating principle and structure of rotary hammers, which are divided into two types:

1. The engine is installed horizontally.

1. The motor stands vertically.

For repairs this does not matter much. All other details are almost identical. Any device consists of two main parts:

1. Electric:

• power cord;
• elements that dampen interference (capacitor, chokes);
• switch;
• engine control device (ECD);
• commutator motor (armature, brushes).

In some models, the switch is combined with a control device.

1. Mechanical:

• reducer (gear) on the motor shaft;
• clutch;
• impact-translational mechanism pneumatic (piston) or mechanical;
• clamping chuck.

In expensive devices, auxiliary mechanisms are installed for convenience and safety:

• depth limit;
• vacuum cleaner;
• mode switch;
• bit fixation
• others.

How to repair a rotary hammer with your own hands?

Many people who are ignorant of technology, when bringing a tool for repair, always describe the breakdown with the words “the hammer drill stopped hammering” or “it won’t turn on.” And only upon meticulous questioning do they remember that they put a lot of pressure on it, did not lubricate it, and worked when the network fluctuated (during operation, the “light blinked”). All this causes device failure and damage, which is divided into:

1. Electrical:

• the device does not turn on;
• sparks are visible in the housing;
• speed does not change;
• there is smoke coming from the body;
• When turned on, the plugs are knocked out (automatically).

1. Mechanical:

• the hammer drill does not hammer;
• a grinding or cracking sound is heard;
• modes do not switch;
• During operation, liquid leaks from the device.

Correct disassembly of a rotary hammer

To repair a particular malfunction, any electromechanical device must be disassembled. Each model has its own nuances in execution. And although the bodies of almost all tools are made of two halves, the disassembly method of one brand may not work with the model of another.

The bodies of many models are made of a front and a rear half, when viewed from the chuck side. The screws that tighten the body are located parallel to the slotting axis, and if the caliber of the cartridge is smaller than the diameter of the body, then they can be easily unscrewed. But on many devices the diameters are the same. Therefore, you must first remove the cartridge and then disassemble the rest.

For other models, the body is disassembled from the side. We unscrew the screws, remove half of the body and all the mechanics at a glance. You can begin the inspection immediately. True, to repair the electrical part you will need to unscrew the handle, but this is not so difficult. The main points of disassembly and assembly can be found on the Internet on the “YOUTUBE” service. Therefore, let's move directly to the repair.

Electrical faults and their elimination

1. The device does not turn on for the following reasons:

• Broken cord (usually near the handle). The cord should be replaced or shortened, cleaned, carefully inserted into the rubber shock absorber seal on the handle and soldered in the appropriate places.
• Poor contact in the switch (eg oxidation).
• Breakage (combustion) of extinguishing elements. They should be replaced. For a while (if there are no such elements), you can connect the engine “directly” to the control unit. Please note - this method can lead to rapid wear of the motor.
• Combustion of the UUD itself. Replace with a new one.
• Winding breakage or burnout. You need to take it to a workshop or a friend to rewind it.

Advice: Check the breakage of the cord or windings, non-contact of the switch and combustion of the extinguishing elements with a tester.

1. Sparks are visible inside the housing. They are called:

• Poor fit of the brushes to the armature due to wear. It is necessary to change the brushes or sharpen them with a file (fine “sandpaper”).
• Oxidation of the anchor. To be cleaned with a student's eraser or alcohol.

1. The speed does not change due to a malfunction of the control unit. It needs to be replaced, but you can get by with it for a while.
2. Smoke comes from faulty windings, brushes or other elements. For example, due to “sticking” of the motor, the windings begin to heat up and smoke. Visual inspection required
3. A short circuit in the cord (insulation breakdown) or switch can cause the plugs to be knocked out.

Mechanical malfunctions and their elimination

There is no clear answer to the natural question of why a hammer drill does not chisel. This may happen due to the reasons given below:

1. The main function is not performed (does not hammer).

• Breakage of any of the metal parts located inside many models in this sequence.

After inspection and identification of a malfunction, the unusable part is replaced.

• Liquid leakage from the cylinder due to damage to the gaskets. Change the gasket.
• Dirt getting inside. Clean the tool.
• Solidification of the lubricant. Remove old grease and apply a new coat.
• Reducer gears are damaged. Once identified, replace it.
• Bearing failure. Replace

1. A grinding or cracking sound is heard due to the following reasons:

• Poor lubrication. Be sure to replace it with the same one. It is prohibited to use grease and other lubricants of this type.
• Cracked bearings or gears. Change.
• The details worked out. For example, the fingers of the mode switch. Change switch

1. Modes do not switch due to the following:

• worn out or broken switch fingers.

The switch needs to be replaced, but for a while you can turn the worn pin 180 o.

• seating breakdown. Be sure to change the switch.
• breakage of fixing covers. Replace.

Spontaneous mode changes occur due to a broken latch. Some people continue to work in this mode, but the best option is to replace the retainer.

1. Liquid may leak due to deformation (rupture) of the gearbox or cylinder gaskets. Once a faulty gasket is identified, it should be replaced.

Prevention during work

The impact-forward device and the gearbox of the device are subject to heavy loads. The components heat up during operation, the seals rub against moving parts and wear out. All this leads to malfunctions. To avoid premature failure of the device, the following instructions must be observed:

• change the gearbox lubricant completely every six months;
• Once every 6 months, remove the brushes, inspect and replace them if necessary;
• after work, blow out the insides with a vacuum cleaner;
• Before work, do not forget to lubricate the rear end of the drill (chisel). If this is not done, the firing pin and seals will quickly wear out.

Advice: Do not press on the instrument. When pressure is applied, the stroke of the striker decreases and it begins to strike faster. Because of this, the striker and seals become unusable.

A hammer drill is a tool without which it is impossible to imagine most construction and repair work today. Therefore, today every person involved in such work strives to have this tool. A video about rotary hammer repair will be of interest to anyone who wants to be able to independently repair damage to this tool.

Finding out the cause of the breakdown

To know what exactly needs to be repaired, it is worth understanding the reasons for the breakdown of the hammer drill. This video will help you do this.

Replacing a bearing in a hammer drill

If, when working with a hammer drill, you hear an uncharacteristic “rustle” or feel that the drill is “slipping,” it’s time to replace the bearing. This video will tell you how to do this.

Disassembling the hammer drill gearbox

The rotary hammer gearbox is designed to transmit rotational motion to the chuck from the engine. This is what powers the impact mechanism. To replace parts or lubricate them, the gearbox must be disassembled. You will learn how to do this from the video.

Another story dedicated to disassembling the gearbox.

Hammer lubrication

For that. To prevent the hammer drill from breaking or malfunctioning, you need to properly care for it. Regular lubrication of the hammer drill is one of the conditions proper care behind the instrument. To lubricate the hammer drill, it must first be disassembled. You will learn how to do this by watching this video.

How to extend the life of a hammer drill

Protecting a rotary hammer from dust means extending its service life. If you want to know how you can make dust protection for your tool with your own hands, watch this video.

An electric hammer drill is perhaps the most popular device that I use at construction sites, repairs, etc.

This tool is operated under rather harsh conditions - vibration, increased dust, power surges and others. All this, sooner or later, leads to the fact that the instrument will fail and require repair.

An electric hammer drill is a complex engineering product that consists of units that ensure the movement of a chuck with a drill installed in it. Essentially, a hammer drill is a device that converts electrical energy into mechanical energy.

The main malfunctions of a rotary hammer and their external signs

Depending on the operating conditions, this device may experience problems both mechanically and electrically.

The hammer drill circuit is quite close to an electric drill. One of the differences is that instead of an ordinary gear pair transmitting torque to the tool, a full-fledged gearbox is mounted in the hammer drill. It is designed to convert the torque generated by an electric motor into reciprocating motion of the chuck.

Problems requiring repair can occur in almost any part of the device. But before starting repairs, it is necessary to diagnose the breakdown and identify the reasons that led to its occurrence.

It should be noted that identifying a breakdown is not particularly difficult, but sometimes you have to disassemble the hammer housing to do this.

Like any technical device, the electric hammer drill has some weak points in its design. They are the cause of breakdowns that require repair. There are often cases when a hammer drill fails due to the fault of a worker who operates it at extreme conditions and in violation of operating rules.

It is necessary to understand that the main faults arise in the electrical or mechanical parts. The most common mechanical problems that occur are:

• the device does not perform its main functions - drilling and drilling;
• jamming of the drill in the chuck;
• the nozzle is not installed in the chuck;
• extraneous noise when the device is operating.

The following defects most often appear in electrical systems:

• the engine does not work;
• excessive sparking of brushes;
• the appearance of burning or the smell of burnt insulation.

The repair begins with cleaning the device body. This is necessary, at a minimum, to prevent dirt from getting into the disassembled hammer drill.

Mechanical breakdowns

When repairing an electric hammer drill, there is often a need to disassemble it. But before you start, you need to make sure once again that the problems arose in the mechanical part of the device. We will analyze in detail what problems occur and how they can be eliminated.

Malfunctions in the gearbox

Untimely maintenance, poorly performed repairs, or operating the hammer drill in extreme conditions can lead to the failure of any part that is part of this mechanism. To identify defects in the gearbox, it is necessary to disassemble it, wash the parts and then perform a thorough inspection of them.

Identified damaged parts must be replaced with new ones. Then assemble the gearbox; of course, you need to put lubricant in it. By the way, the brand of lubricant should be indicated in the instruction manual.

Chuck malfunction

If the nozzle does not fit working position, then most likely the reason lies in the cartridge. To eliminate this defect there is no need to disassemble the instrument. As a rule, obstacles to installing the nozzle are due to the fact that some debris has gotten inside the cartridge.

The mode switch is faulty

To identify malfunctions in the mode switching device, the hammer drill will still have to be disassembled. In principle, the defect can be identified by carefully inspecting the switching mechanism.

In principle, the main components in which breakdowns most often occur and require repair are listed. Meanwhile, there are several other types of defects that can arise from various reasons. For example, there is no impact hammer mode. That is, the drill rotates together with the cartridge, but the impact action is not work surface does not provide. The most common cause in this case is a floating bearing. Another cause of this malfunction may be damage to the steel striker. In both cases, replacement of the defective part is required.

There are often cases when when you turn on the tool, the engine runs, but the chuck does not rotate. This happens most often because the gearbox is jammed. By the way, keeping the hammer on for a long time is unacceptable when the chuck is not working, as the motor winding may burn out. The hammer drill will have to be disassembled and defects in the gearbox eliminated. They can be caused either by damage to the gears or by debris getting into it.

Another defect is that the chuck cannot lock the drill. This problem may occur with a tool that has already long time exploited. The cause of this problem lies in the wear of the fastener housing.

Electrical faults

Serious problems can also be caused by malfunctions associated with the electrical part of the hammer drill. By the way, a failure to operate can be caused by a trivial lack of voltage in the outlet.

By the way, troubleshooting should start with less. That is, you need to check the presence of power in the electrical network, the integrity of the wire and socket.

By and large, if an instrument does not show any signs of life, the likelihood is that it is the electrical part of the instrument that has failed. The main electrical defects include the following:

No voltage in the supply network, cable break

You can connect any electrical appliance. If there is voltage in the network, then it is necessary to check the integrity of the cable.

To identify this defect, inspect it, then, using a tester, ring it. To eliminate a cable break, you can either solder it or twist it. But it's best to replace it.

Start button malfunction

The cause of this defect may be simple oxidation of the contacts in the button. To check this assumption, it is necessary to dismantle the rear cover of the casing. In the absence visible traces oxidation, it is advisable to use a tester. To correct this problem, you can clean the contacts, but it is better to replace the power button.

Erasing brushes

With prolonged and intensive use of a hammer drill, wear occurs on the brushes through which the electric current to the engine. When worn too much, they begin to spark and a burning smell appears. The brush must be at least 8 mm long.

Once this and a smaller size are reached, they are replaced. The replacement procedure is quite simple and anyone can handle it, even if they are not familiar with the basics of electrical engineering.

Speed ​​controller failure

If this problem is detected, it is advisable to replace the entire assembly. But, in fairness, it should be noted that this defect does not occur often.

Motor malfunction

This is probably the worst defect that can happen to an electric tool. The user must understand that it is better not to repair the engine independently. For this purpose, there are specialized workshops equipped with all the necessary repair and diagnostic equipment.

When the engine is running, a certain layer of carbon deposits forms on the manifold. You can remove it yourself and then try to turn it on. If this operation does not help, then it is necessary to ring the armature and stator. There are certain requirements for winding resistance.

Repair of these components can only be carried out in an electrical workshop. It is permissible to do this work at home, but only if you have special equipment and certain knowledge regarding the operation of the electric motor. This operation, performed at home, will significantly reduce the cost of repairing the rotary hammer as a whole.

Important! Repair of the device is carried out with the tool disconnected from the electrical network.

Required tools and materials

To repair and restore the functionality of the tool, you will need some wrenches, both regular open-end and hexagon wrenches, and screwdrivers with different slots. A puller will be required to remove the bearings.

Disassembly and assembly of the hammer drill must be carried out using kinematic and electrical circuits hammer drill.

Quickly find a breakdown

To diagnose a faulty hammer drill, most often there is no need to use special equipment and tools, with the possible exception of a tester and a device for rewinding the motor.

The cause of the breakdown can be determined using a routine inspection.

And to identify problems in the mechanism of the tool, it is advisable to know and understand its structure and operating principle.

Operating rules or how to protect the device from damage

To ensure long-lasting and efficient work with an electric hammer drill, it is enough to follow a few simple rules. In particular:

• When working, it is not advisable to put too much pressure on the tool; at least this is not necessary, and moreover, with excessive pressure, the tool will fail faster.
• It is not permissible to operate the electric hammer drill in idle mode.
• While working with porous materials It makes sense to turn off the impact mechanism. When working with special hard materials It is advisable to use lubricant.
• When working, especially for a long time, it is necessary to monitor the heating of the housing, especially in the place where the gearbox is installed. If there is noticeable heating, you must stop the work and wait until it cools down. Water cannot be used for cooling; its use may damage gearbox parts.
• Work with the tool should be carried out in the following mode - at least a 10-minute break after half an hour of work.

DIY repair

Repairing a rotary hammer with your own hands can only be partially done. But, for example, it is still better to perform such a unit as an electric motor in a special workshop.

It is best to carry out repairs in the warranty workshop of the company from which it was purchased.

To lubricate the hammer drill components, you must use only those materials recommended by the manufacturer.

Barrel perforator repair

A barrel hammer differs from a traditional one in that the electric motor is located vertically and cannot operate in drilling mode.

Therefore, due to the design features, in order to get to certain components, additional operations will have to be performed, in particular, to inspect the electric motor, it is necessary to remove the lower part of the casing or cover. And for replacing brushes, special technological holes are provided in the body.

Replacing the power button

To replace this button, you will have to disassemble the case, disconnect it and install a new one in its original place.

Replacing brushes

To replace brushes, it is necessary to provide access to the brush assembly. To replace, you need to release the brushes from the lock and install new ones in their place.

Replacing bearings

If you hear extraneous sounds, then there is a high probability that the bearing has reached a certain degree of wear. That is, it needs to be replaced.

To do this, it is necessary to completely or partially disassemble the housing and gain access to the unit in which it is installed. A puller may be required to remove it. By the way, some bearings can be secured using retaining rings.

Replacing the cartridge

To replace a cartridge that has expired, you must first take into account which company produced this product. The whole point is that the cartridge fastening schemes different manufacturers have their own characteristics.

For example, to dismantle the chuck in a Bosch rotary hammer, you need to do the following manipulations - loosen the locking ring, pull out the chuck and install a new one in its place.

Drunk bearing repair

In some models of this tool, the impact is achieved using a bearing. During intensive use, it may be destroyed.

To repair it, you will need a flathead screwdriver. After disassembling the housing, the bearing must be removed from the housing, disassembled, worn parts replaced and reinstalled.

Repair of raster bushing and impact bolt

To repair the impact mechanism of the hammer drill, it is necessary to remove the raster bushing; to do this, it is necessary to release the spring and the locking ring. After this, the impact bolt is replaced with a new one, or sent for restoration.

Replacing the sleeve

The sleeve fails quite rarely. To replace it, the old one must be removed from the aluminum case and a new one installed in its place.

If the warranty period for a rotary hammer has expired, you will have to repair it yourself. As a rule, actions come down to replacing faulty parts, and today we will talk about typical breakdowns, selecting components and performing repairs yourself.

How does a hammer drill work?

A hammer drill can be classified as a tool that has a device of increased complexity. However, a sequential examination of the details and principle of operation will help to thoroughly understand the nuances of the mechanism and troubleshooting.

The source of movement, as in many other construction tools, in a hammer drill is single phase motor with a wound rotor. We will consider it separately, but now we will take the gear mounted on the front armature shaft as the reference point. It is she who sets the rotation of all other elements of the system.

Barrel perforator structure: 1 - power cord; 2 — carbon brushes; 3 - electric motor; 4 - switch; 5 - eccentric mechanism; 6 — impact mechanism; 7 - quick-change cartridge

In a barrel hammer, the motor and drive gear are located vertically. Key difference What distinguishes the pistol-type tool from this is the presence of an intermediate gearbox. There is nothing tricky about its design: a flat gear from the engine rotates two others with different gear ratios. One of them transmits rotation to the main shaft, the other rotates the eccentric shaft with a connecting rod, which provides reciprocating movement of the impact mechanism.

In horizontal (pistol) type hammer drills there is no transfer gear as such; rotation is immediately transmitted to an intermediate shaft located below the axis of the main spindle. This shaft is mounted on two bearings, between them there is a “drunk bearing”, which, when rotated, oscillates and sets the firing pin piston in motion. At the protruding front end of the shaft there is a gear, through which rotation is transmitted to the barrel.

Pistol type hammer drill device: 1 - switch; 2 - electric motor; 3 — brushes; 4 — “drunk bearing”; 5 — “flying” piston; 6 — striker; 7 - quick release chuck SDS

Any rotary hammer has mode switches. In the barrel, they simply lift the gears of the transfer gearbox, disengaging them. A pistol hammer drill can use one of two control schemes. In the simplest case, one switch displaces the intermediate shaft, which, being extended as far forward as possible, engages with the cartridge gear, but at the same time the rotation transmission clutch to the swing bearing is disengaged. In the middle position, both mechanisms are included in the transmission, and in the most recessed position, only the drummer works. The outdated kinematic circuit has two switches, one of which disengages the oscillating bearing clutch, and the other moves the intermediate shaft.

Engine Troubleshooting

If the rotary hammer engine has a manufacturing defect, the latter manifests itself in the very first months of operation. Otherwise, the cause of the breakdown is often a violation of operating techniques or extreme wear of the components.

The main element of the motor part, subject to intense wear, is the graphite brushes that transmit current to the rotor windings. When the brushes are worn, their pressure weakens, causing the gap between the graphite and the armature lamellas to increase and intense sparking to occur. The sound of this malfunction cannot be confused with anything: when you turn it on, you can hear a strained hum, the collector is showered with a sheaf of sparks, and the rear part of the engine heats up intensely.

The motor windings are made of wire in varnish insulation, which, due to overheating, loses its dielectric properties, cracks and crumbles. Small short circuits between adjacent turns can be identified by the characteristic hum of the engine during operation. Unfortunately, it is almost impossible to rewind the stator and armature at home, but most engine parts are standard and easy to find replacements for.

Other vulnerable parts are bearings. There are two of them on the anchor: the rear one is fixed in the electrical part housing inside the vibration-damping cap, the front one is inserted into the seat of the gearbox housing or screwed to it with a slip die. Bearing wear is quite easy to determine: when rotating by hand, their movement is either too free with a characteristic rustling sound, or there is wedging, play and extraneous noise. The bearings have a closed cage and are not designed for maintenance. It is much easier to replace them with new ones; just write the number on the separator cover or the end of the outer race.

Replacing the button and brushes

During the operation of a high-quality hammer drill, the button may have to be changed more than once. It is optimal if you purchase a button in advance for a specific model. If you need to remove the faulty part for a sample, sketch out a connection diagram on paper indicating the color coding of the wires. Some of the buttons have screw clamps and to unscrew them you will need a narrow slotted screwdriver. Some buttons come with clips spring type To loosen them, you need to drive an awl into the hole next to the wire entry. It is quite rare to find disposable spring clamps, the wires from which cannot be disconnected. The wires from the old button will have to be cut, stripped and tinned, and then connected to the new button in accordance with the connection diagram.

It is quite easy to change brushes in a rotary hammer; the channels for them in some models are brought out and closed with plugs for access without disassembling the tool. Otherwise, you will only have to remove the housing of the electric motor part of the tool and carefully inspect the commutator assembly. The brush seats are located inside or near the plastic posts that hold the rear bearing plug; two wires go to them. The mechanism for attaching and pressing the brushes varies from model to model.

In most cases, to remove the brushes, you only need to pull out two metal tabs with pliers, unscrew a couple of screws, or unfasten the springs of the clamps. During periodic inspection, it is recommended to remove the brushes and check for chips, and clean the landing grooves from dust and dirt. Be careful not to confuse the left brush with the right one, keep them in their original position when installing. As a rule, brushes are lapped at an individual angle, changing which will either require re-grinding or will lead to destruction of the graphite element.

When replacing worn brushes, it is only important to select correct size and cross-section, and then grind in the brushes by running the engine for 2-3 minutes without load in the no-impact mode. Nowadays, almost every rotary hammer is equipped with a set of replacement brushes, but replacements can also be found from the remnants of already used ones.

How to replace bearings yourself

The hammer drill contains from five to ten radial rolling bearings different sizes and the need to replace them is only a matter of time. It is very important to periodically disassemble and evaluate the degree of wear of these components, otherwise more serious malfunctions may develop in the future.

Almost every bearing in a hammer drill is quite easy to remove; the seating dimensions for them are selected with high precision. In some cases, a retaining ring may prevent removal. If it is not there and the bearing refuses to be removed, a universal two-jaw puller is used. If a puller is not available, then the part on which the bearing is seated must be clamped in the soft jaws of a vice, and then the worn element must be knocked off by striking the inner ring through the adapter.

When seating a new bearing, direct hard blows must not be applied to it. You should use an elastic attachment, such as a trim polypropylene pipe. It must first be cut obliquely so that the impact force falls exclusively on the inner race. This way, the rolling elements will not leave microscopic dents on the grooves.

Chuck malfunctions

The SDS cartridge consists of a fitting with one or two holes in which balls are seated, usually with a diameter of 6.7 mm. The balls move freely in the holes while the plastic body of the cartridge is pulled back; in the normal position they are tightly pressed by a spring through a massive steel ring.

To disassemble the cartridge, you need to pry out the front boot with a screwdriver and remove the locking ring from the fitting. The remaining parts are simply put on the fitting and can be removed without additional manipulation, it is only important to return them to their place in the correct order.

As a rule, the main cause of chuck malfunction is ground off balls or a dented plate and pressure ring. Because of this, the equipment either does not hold at all or flies out during operation. You can get such balls in any quantity by breaking bearing number 106. The mounting holes and splines inside the bushing have a much longer life, but if the replacement does not give the expected result, you will only have to change the fitting assembled with the barrel.

Please note that rapid wear of the cartridge parts occurs due to loose sealing of the anthers, both the front one and the annular one on the fitting. The drill shanks should always be kept lubricated, and when drilling the ceiling, use a special dust washer.

Repair of gearbox and impact mechanism

Now we have come to the most substantive part of our instructions. Due to differences in the structure of the transmission part and the shock pulse generator in different families of rotary hammers, their maintenance and repair are carried out according to different schemes.

Barrel perforators

The drive gear of the transfer gearbox is mounted on the engine bearing, the other two have their own stops. They need to be periodically checked for jamming and play, and replaced if necessary.

The connecting rod mechanism has its own bearing, which is usually mounted on the cam of the eccentric wheel, sometimes at the base of the connecting rod itself. Occasionally, a sliding bearing is used in this place, which requires the constant presence of lubricant with a standardized viscosity index. Wear of this unit often requires replacement of the eccentric barrel and connecting rod.

The transmission of rotation is carried out by a straight or bevel gear; the constant presence of lubricant is also important in this place. The need for replacement is determined by blackening, liquefaction and the presence of shiny inclusions.

Pistol hammer drills

In rotary hammers with a horizontal rotor, problems can arise from wear or jamming of the bearings. This is the most dangerous malfunction for all hammer drill components: fragments of a broken bearing can get into the parts of the impact mechanism and damage them.

The landing of the intermediate shaft and the “drunk bearing” is often made according to an individual scheme. For complete disassembly you need to unscrew the clamping bracket of the front end of the shaft and disconnect the switch lever.

A typical failure of a horizontal gearbox is wear of the transmission gears. In the absence of a press, removing them will not be an easy task; it is much easier to break them by making a couple of cuts to 2/3 of the thickness. The new gear is pressed in after preheating to 150-200 ºС; this can be done with a hair dryer or in the oven.

All types of gearboxes should be periodically complete cleaning and changing the lubricant. After disassembly, all parts are thoroughly washed in kerosene, getting rid of fragments of broken elements and metal shavings. After this, a special type of lubricant is applied to all moving parts.

Raster coupling

The barrel of almost all types of hammer drills has the same structure. The outer sleeve of the coupling rests on a needle bearing in the front of the gearbox housing. The main rotation transmission gear along with the safety clutch is fixed on the outer side of the cup. To remove them, you need to remove the retaining ring by first compressing the spring with adjustable pliers.

Disassembling the insides of the raster coupling is also easy. They are fixed with a locking ring, which is removed through a pair of side holes with a regular screwdriver. Once the ring is removed, the parts inside can be pressed out by inserting a screwdriver into the front of the barrel.

Inside there is a “flying” impact bolt and an industrial mass - a shock force receiver. Most bolts are assembled; rubber gaskets and seal rings often wear out. It is recommended to change these elements at every service. The bolt itself and the industrial mass can be split due to fatigue during long-term use. These elements cost mere pennies and if there is the slightest trace of flaring, it is also better to replace them immediately.

It is difficult to give more specific recommendations for repairing the raster coupling and gear part: each manufacturer kinematic diagrams may have slight differences. However, most of the faults are clearly visible during inspection and revision. In this regard, it is recommended to save the assembly diagram from the instructions for the tool; it should also be used when searching for components, which are determined by the serial number of the list of parts used.