The hammer drill works but does not hammer

A universal chipping tool with a rotary impact mechanism, also known as a hammer drill, is used by construction crews, electricians and repairmen. They also use it in the home workshop.

Like other electrical appliances, a rotary hammer sometimes breaks down. Take it to a service center and leave a certain amount there, or take advice and repair the instrument yourself - everyone decides for themselves. If the decision to repair a rotary hammer at home has been made, you should first study the features of its design and the advice of experts on diagnostics and repair.

Disassembly and assembly procedure

Having cleared and freed a place in the workshop for repair work on electrical equipment, and prepared the necessary set of tools, the hammer drill begins to be sequentially disassembled to determine the malfunction, carefully inspecting each component and part. The tool is disassembled according to the following scheme.

How to disassemble an electric motor

To inspect the moving part, the first thing the master does is separate it from the impact mechanism and gearbox. To do this, unscrew the holding bolts (there are four of them), then:

The rotor (or rotor armature) is removed from the gear drive sleeve.
The separated motor is removed from the housing.
The rotor and stator windings are diagnosed separately.
The rotor armature is checked for the integrity of the windings and the absence of bridging and twisting turns. The technician will also pay attention to the bearings - if their integrity is compromised, they are removed and replaced.
Having unscrewed the holding screws, the technician removes the stator by slightly shaking or tapping it.
The rotor and stator windings are examined with a multimeter, measuring the resistance on the lamellas.

Important. If the stator winding is broken, the technician can twist it in a workshop, but if the fault is in the rotor armature, it will most likely have to be replaced.

The brushes sparkle

When the brushes sparkle, the first thing it is recommended to do is clean the tool from dust. If the effect of sparks does not stop, the device is disassembled and the integrity of the brushes themselves is checked. If necessary, one or both brushes are replaced to avoid shorting.

Electrical problems

If the hammer drill is connected to the network, but upon startup there is either a lack of impact, or a lack of torsion, or both, the reasons should be sought in the electrical plane. Typically, these problems are accompanied by the following symptoms:

extraneous sounds that are not typical during normal operation;
the motor hums, but the drive shaft does not turn;
graphite brushes spark;
a distinct burning smell, visible fumes, black smoke;
The hammer housing is very hot.

The motor hums, but there is no rotation

In this case, the source of the problem is hidden in the engine gearbox: it prevents the rotor from spinning. If there is no sound, there are more reasons:

power supply failure;
failure of the start button;
short circuit in the coil windings.

One way or another, you will have to disassemble the electric motor, check for a short circuit, and only then make repairs.

Sparking graphite brushes

This malfunction is associated with wear of the brushes - they should be replaced. If the sparking does not stop even on new brushes, the reason is in the engine, or more precisely, in the stator and rotor windings. When assembling a rotary hammer at the factory, a special protective varnish is applied to these windings, which prevents dust from penetrating into the rotor and stator.

Stator with winding

If periodic maintenance is not carried out, there will be so much dust on the windings that the varnish will rub off. This may result in a short circuit. Because of this, sparks may appear on the brushes. To check for a short circuit, use a multimeter.

Preventive measures:

periodic change of brushes;
oil lubrication of the rotor shaft bearings;
applying a new layer of varnish to the rotor and stator windings to replace the worn one.

Replacement of main components

If during diagnostics the technician determines that one of the main components has become unusable, he will replace it to avoid damage to other parts of the device.

How to remove the mode switch

To diagnose internal components, it is necessary to remove the hammer housing and clean the surface of the components from dust. The analysis begins with the compartment of the operating mode regulator.

It is moved all the way - as a rule, this is the extreme right position (below the rebound mode icon), after which, using a flat screwdriver, the regulator is removed from its socket.

Mechanical failures

If you hear the sound of the engine rotating, but the device does not perform functions, this means that problems are observed in the operation of the mechanical “stuffing” of the instrument:

the impact does not transfer to the cartridge or the nozzle, i.e. stopped hitting and the blow disappeared;
the rotation of the axis is stopped;
hammers, but does not twist;
works only in one position;
the nozzle slips in the chuck clamps or, conversely, gets jammed after use.

Lost impact on the hammer drill?

Reference. The listed mechanical problems indicate malfunctions in the chuck mechanism. If grinding and extraneous sounds come from inside the case, in order to identify and eliminate the malfunction, you will have to disassemble the entire instrument and inspect the transmission units.

Daily care and storage

In order for the tool to serve the master properly for many years, during operation it is recommended:

run the device “idle” before starting work. If the hammer drill shows signs of breakdown, work is stopped and diagnostics begin.
After completing the work, take care of the cleanliness of the rotary hammer - it is important to remember that electrical appliances “do not like” water; cleaning is carried out with a vacuum cleaner and rags.
If the hammer drill is working in the cold or has been moved indoors from outside, do not start it right away. Allow the components to “warm up” and the lubricant to thaw.
Carry the hammer drill in a special box or suitcase (usually included) to avoid dust and construction debris.

Thus, if you follow objective precautions and operating rules for the hammer drill, it will last a long time and without breakdowns. If trouble does happen, the suggested advice from the experts will help determine the essence of the problem and fix the breakdown in a timely manner.

Everything a home mechanic needs to know about rotary hammer repair

A universal chipping tool with a rotary impact mechanism, also known as a hammer drill, is used by construction crews, electricians and repairmen. They also use it in the home workshop.

Like other electrical appliances, a rotary hammer sometimes breaks down. Take it to a service center and leave a certain amount there, or take advice and repair the instrument yourself - everyone decides for themselves. If the decision to repair a rotary hammer at home has been made, you should first study the features of its design and the advice of experts on diagnostics and repair.

The structure of the tool and its mechanism
Troubleshooting
Mechanical failures
Electrical faults
Disassembly and assembly procedure
Removing the cartridge
How to remove the mode switch
How to check the start button and brushes
How to disassemble an electric motor
How to disassemble and check other elements
Possible faults
Doesn't hit - reasons
Doesn't spin or drill
The drill does not stay in the chuck and flies out
The brushes sparkle
The tool gets very hot
Doesn't hold a cartridge
Replacement of main components
Bearings
Start button
Brushes
Cartridge
How to repair a barrel tool?
Daily care and storage

How to fix a rotary hammer with your own hands

The repair procedure at home is the optimal solution and will cost less than the services of service centers. Instrument repair is expensive and it is not a fact that you will find a conscientious repairman. Before you think about how to make a hammer drill, you should acquire the necessary tools and stock up on theoretical knowledge on how to disassemble and assemble a hammer drill. After completing the repair, run it in gentle mode.

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Barrel hammer drill repair

This procedure is no different from repairing a conventional hammer drill. Honor states that the engine and shaft are located vertically.

Oil is leaking from the drill

Leakage is a direct indicator of wear and tear on certain parts inside the mechanism. Spin the model and make diagnostics, change the lubricant if necessary.

Rotary hammer repair: advice from professionals on disassembling household and professional devices

A hammer drill is an indispensable tool for drilling holes in concrete walls and many other similar works. Sometimes this device may break down. This article describes the device and principle of operation, diagnosis of the most common faults and how to repair a rotary hammer with your own hands.

Device design

The hammer drill has a strong impact function that a conventional drill does not have. This is achieved by the presence of special design elements that create a pneumatic push of the working tool with high kinetic energy.

The rotating motion of an electric motor is converted into oscillatory motion by compressing air between two pistons. Compression is created by vibration of the piston, which is transmitted to it from the electric motor using a special gearbox.

Despite the complexity of the design, most breakdowns are easily diagnosed and fixed; in difficult cases, to repair rotary hammers, you should first refer to the detailed instructions.

Basic faults

There are more than a dozen of the most common causes of rotary hammer malfunctions. Breakdowns can be caused by mechanical or electrical problems.

When the motor is running, the following mechanical breakdowns may occur: the drill does not rotate, it does not make impact movements, the drill is not fixed in the chuck or is stuck in it, there are extraneous noises when the equipment is operating.

The following characteristic signs indicate an electrical malfunction: there is no attempt to rotate the electric motor, strong sparks are generated on the electric brushes of the commutator during operation, acrid smoke is emanating from the device or there is a corresponding unpleasant odor.

Repair procedure

In order to repair the equipment, it must be disassembled. To do this, you need the following equipment: wrenches, screwdrivers, vices and bearing pullers. When lubricating mechanical parts, you will need a rag and solvent.

To repair the electrical part of the hammer drill, you may need winding diagrams and wires.

To disassemble the device, you must first remove the cartridge. After this, the body opens. If necessary, you can open only the part with the engine or the compartment with the gearbox. To repair faulty parts of a rotary hammer, you should first study photographs of such work.

Let's look at the most common equipment malfunctions, the procedure for inspecting and repairing rotary hammer problems.

The hammer drill does not hit

The device turns on, you can use it to drill holes like an ordinary drill, but the impact mechanism does not work. This malfunction may be caused by a failure of the floating bearing or destruction of the striking mechanism. In this case, the failed parts must be replaced.

No rotation

When the device is turned on, lack of rotation may be caused by electrical or mechanical faults. If the device does not react at all when turned on, then the problem is electrical. A wire could break, a switch might break, or the motor coils might short out.

If instead of working there is a hum, but there is no rotation, then the problem is mechanical: the rotor of the electric motor cannot perform rotational movements.

Sparking brushes

The most common cause of sparking is reduced brush thickness. As they decrease, the pressure of the pressing springs weakens, and an additional gap appears through which large sparks jump.

If replacing the graphite brushes does not help eliminate sparking, then the reason lies in a short circuit in the stator or rotor windings and they need to be rewinded. A tester is used to find a short circuit.

In order to reduce the likelihood of motor failure, it is necessary to monitor the condition of its brushes and bearings. The windings should be coated with an additional layer of dielectric varnish. Keep engine parts clean. Dust easily settles on a surface coated with lubricant.

High heat

Excessive temperature rise during operation may be caused by a motor malfunction. In this case, immediate repair is required.

Replacement of main parts

When using the device, you must ensure that it is in good working order. When the first signs of a malfunction appear, urgent repairs are necessary. In order to avoid serious repairs, you need to monitor the condition and, if necessary, change the following elements: bearings, power button, graphite brushes and cartridge.

The bearing is replaced if lubricant has leaked from it, it turns hard or creaks. To perform this operation you will need a puller and a wooden hammer.

The power button is very easy to change. This requires disassembling the case. In this case, it is necessary to ensure that the device is disconnected from the network.

The brushes are also very easy to change. Professional equipment does not require disassembling the housing. The hammer drill chuck can be replaced entirely or failed elements can be replaced.

In order for the equipment to serve for many years, it is necessary to perform maintenance, keep it clean, regularly clean and lubricate moving parts and replace brushes and bearings. In this case, repairs may not be necessary at all; the equipment will serve properly for many years.

Photo of the hammer drill repair process

Rotary hammer design, assembly diagram and spare parts list

The tool consists of a single-phase motor and rotor. A gear located on the armature shaft is responsible for rotational movements. Between them there are bearings, one of which is “drunk”, it is this that transmits movement to the working parts.

The hammer drill does not rotate under load

Most likely, the load does not correspond to the permitted norm, resulting in this defect.

Why does the hammer drill heat up?

Most often, the reason for this is the length of operating time and heavy loads on the tool. The engine interacts with working units, which may result in overheating. When it appears, turn off the tool, give it time to cool - at least half an hour.

If the rotary hammer hammers but does not drill

The conical spring holds the clutch, if it becomes loose, a problem may arise;
The locking roller no longer locks the large shaft gear;
stops working .

In this case, it is enough to replace or tighten up the problematic parts and start in a gentle mode.

The hammer blow has disappeared - what to do?

As is clear, nothing never ends. And reliable equipment breaks down. Somehow, in the midst of work, he finished hammering . The machine was working in rotation mode, but the shock suddenly disappeared.

The gearbox was disassembled and the cause of the breakdown was identified. The bushing in the barrel body, in which the firing pin directly carries out the impact work, was broken. As a result, the striker became jammed in the fragments of the collapsed bushing.

The service center advised to replace the barrel completely. It turned out that the bushing is pressed into the barrel at the manufacturer and is not supplied separately. I had to buy a whole new barrel.

In this article we will tell you how to put the hammer drill into working condition yourself after this, in general, simple breakdown. If you have the skills to repair power tools and the desire not to pay someone your hard-earned money, then we take the tool and start disassembling the machine.

Tools

You will need two ordinary flathead screwdrivers and one Phillips head screwdriver. One of the flat-head screwdrivers should be thin and narrow, no more than 4 mm wide. You will also need a wire hook to remove the retaining ring. It can be made from a bicycle spoke, the main thing is that the wire is rigid and does not bend easily. You will also need a rubber mallet or wooden mallet.

How to repair a hammer drill if it stops working. We find out the causes of tool failures

The construction industry is developing and adding new tools every day. For several years now, the hammer drill . Essentially, this is a regular drill that is equipped with an impact effect. Every second worker encounters malfunctions.

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 file. The splines on the intermediate shaft are modified in the same way.

Restoring the teeth of the intermediate shaft clutch

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 completely replacing the rolling bearing.

Friction bearing

Reasons for the lack of impact

At first glance, it seems that the impact mechanism has a simple design and there is nothing to break. Load, dust and vibration gradually take their toll. Typically, the impact force decreases as the mechanism wears out and eventually disappears. The sudden disappearance of the impact is explained by the deformation or destruction of some parts.

Mode switch

Mechanism parts may come out of the guide grooves. This may be a consequence of deformation, wear, or frequent use of the tool with the mode not fully engaged. The malfunction is eliminated by installing the parts in their places or replacing them with new ones.

The hammer drill does not rotate under load

If the hammer drill has stopped hammering , the feasibility of repairs should be assessed. There is no point in restoring imitations of popular brands, cheap modifications - they are not designed for a long service life, the cost of repair is approaching the purchase of a new power tool. Models of famous brands last longer; their replacement is often caused by the appearance of modifications with additional capabilities and obsolescence.

Lack of preventive maintenance after 100-80 hours of operation will inevitably lead to failure of the hammer drill.

Replacing brushes

If the location of the brushes gets very hot, then most likely this part requires replacement. It is recommended to first check the condition of the elements: replacement is carried out if they are completely worn out. The procedure will require a high-quality electrical screwdriver.

The device is disassembled according to the described instructions, after which new parts are placed in place of the old brushes.

Attention! Some models differ in the clamping mechanism, so it will have to be removed before replacing.

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, differ in the design of the intermediate shaft and the installation of various bearings.

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.

Repair kit for rubber sealing rings for a Bosch 2-26 rotary hammer

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 raster bushing, which makes it impossible to transmit the shock pulse to the working tool of the hammer drill.

Tool shanks for hammer drill chucks Bosch 2-26

"Drunk" bearing

It is mounted on the shaft at an angle and drives the piston. If there is wear or damage, the bearing must be replaced.

Mode switch

How to repair a barrel tool?

The design of electric rotary hammers varies depending on the location of the motor. It happens:

vertical (or barrel) - in which the engine stands vertically relative to the rotational-shock axis;
horizontal, that is, the engine is parallel to the axis of rotation.

Disassembling a barrel perforator is easier than its horizontal counterpart - two covers of the device provide separate access to the mechanical and electrodynamic parts. The upper casing exposes the gear unit and pistons. The lower one allows you to check or replace the brushes and diagnose the power unit.

Hammer hammer impact mechanism

Most modern rotary hammers have an electro-pneumatic impact mechanism. “Electric” means that the mechanics are driven by an electric motor, and “pneumatic” means that the striker hitting the drill shank is driven by air.

Engine rotation transmission gear
"Drunk" bearing
Piston
Drummer (“flying piston”)
Trunk
Striker
SDS cartridge

When you press the button, the engine transmits rotation to a shaft with a “drunk” bearing, which in turn drives the piston inside the barrel. As the piston moves forward, air pressure increases between it and the striker. The striker moves towards the striker and hits it. The striker transfers the impact energy to the drill. Then the piston moves in the opposite direction, creating a vacuum area in the barrel. Due to this, the striker returns to its original position, after which the entire cycle is repeated.

Most rotary hammers have two or three operating modes:

combined mode: impact and rotation of the drill;
Rotation lock mode: only the impact mechanism works;
impact blocking mode: the hammer drill can be used as a drill or a mixer for preparing building mixtures.

The structure of the tool and its mechanism

Device
The functional purpose of a hammer drill is determined by its internal structure.

The reinforced shock-rotational mechanism of the tool is the so-called “oscillating bearing” or “crank rod”, which, rotating from the engine, transmits vibrations to the pneumatic pistons (or piston), after which the air pumped into the pistons pushes the striker with a blow.

An impact force of 17-20 kilojoules and parallel rotation of the displacer due to the transmission gear ensures that the chisel or drill enters high-density material. It is necessary for punching through holes or drilling holes for electrical wiring or plumbing pipes.

Video about the construction of a hammer drill and impact mechanism:

Malfunction of the drilling mode in the hammer drill

The list of the most common malfunctions of power tools invariably mentions the situation when a BlackDecker, Bosch, DeWALT or any other brand hammer drill does not work in drilling mode, but is actively chiseling the material being processed.

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Effective impact is an important advantage of a hammer drill, but without rotation of the drill it will be almost completely neutralized. In this case, the functionality of the tool will be limited to short-term operations with a chisel, lance, etc. – long-term operation in the “chiseling without drilling” mode will quickly lead to breakdown of the mechanism.

Usually the simplest answer to the question is why, when switching to drilling, the hammer hammer hits as if in impact mode. Most likely, this is caused by a breakdown of the mode switch - a rather vulnerable component of many types of power tools. Replacing or repairing a switch can be done quickly and does not require large financial outlays.

You can preliminarily determine why a Makita, Metabo, Interskol, etc. hammer drill beats but does not drill by sound: if you can clearly hear the hum of the engine, but there are no rotational movements, then obviously the problem lies in a jammed gearbox. Sometimes gear teeth break off - broken fragments prevent them from turning.

Also among the most common reasons why hammer drills from Elitech, Hammer, Hitachi, STANLEY, RYOBI, Skil and other brands stopped drilling, service specialists name:

wear of the teeth of the protective coupling - a characteristic “ratcheting” sound will be heard;
abrasion of gear teeth between the engine shaft and the intermediate shaft;
weakening of the conical spring holding the coupling;
lack of fixation of the large shaft gear.

In any case, diagnostics will require disassembling the body and mechanical part of the instrument.

The masters of the “Udachnaya Tekhnika Service” center can easily cope with this work, select the necessary spare parts from the company’s own warehouse, and perform cleaning, lubrication, preventive checks and adjustments of other components. And all this - quickly, at a competitive price and with a guarantee of quality services!

Striker and striker

These parts are made of high-strength steel. The firing pin rarely fails, but the bushing in which it moves absorbs some of the impact energy and breaks down over time. The fragments jam the firing pin and the hammer stops hitting.

The firing pin (“flying piston”) has a compression ring. When it wears out, part of the air passes into the gap between the cylinder in the barrel and the firing pin. The more wear, the weaker the impact. The problem is solved by replacing the ring with a new one.

Sometimes the striking part of the “flying piston” breaks on the firing pin. This is usually the result of pressure on the hammer when drilling holes. The drilling speed does not increase, but the load on the mechanism increases, which accelerates wear. Repair consists of chamfering on an emery machine or replacing a part.

How to disassemble and check other elements

Having dealt with the electrics, the technician will begin to examine the mechanical components:

Separate the plastic casing from the gear drive. In this case, it is recommended to run a magnet along the casing so that individual parts, for example, ball bearings, do not roll out.
The axial shaft will be removed from the “drunk” or floating bearing; it is its “swinging” that transmits the shock impulse to the cartridge.
Remove the drive gears (with crooked and straight teeth) by removing the retaining rings, after which the bearing will also be separated.
Separate the retaining ring from the raster bushing and unscrew the impact bolt, after which he will check the integrity of the impactor, made of durable metals.
After examining the components and, if necessary, replacing damaged elements, the structure is assembled in successive blocks. Craftsmen recommend lubricating every part and assembly during assembly.

Important! Two needle bearings are installed in the “drunk” bearing ring and on the raster bushing. The first of them experiences extreme loads during operation and often needs to be replaced.

The drilling part is stuck in the chuck

Sometimes you don’t need to disassemble a hammer drill to understand why it doesn’t hit. It happens that the drill gets stuck in the chuck.

Drill jamming

This is due to the following reasons:

When installing the drill into the chuck, no lubricant was applied to the shank. It is necessary to carefully move the rubber seal on the cartridge and add WD-40 to the joint.
The shank broke. In this case, you need to first inject WD-40, and only then try to remove the drill. If this does not work, you should disassemble the cartridge and knock out the drill.
The role of the drill is played by a drill with an adapter. Here, too, the joint area is treated with WD-40 first. After a few minutes, you can begin to lightly tap the chuck with a hammer, systematically loosening the drill with your other hand. After this, the clamping jaws of the chuck should unclench.

Can't do without WD-40

The drill flies out of the chuck

When, during operation under load, the drilling mechanism falls out of the chuck, the reason is the wearout or breakdown of the latter. It is necessary to remove and disassemble the cartridge to determine the source of the problem.

Important! It will not be possible to continue working with such a screwdriver; moreover, a falling drill bit can cause injury.

The cartridge flies off

If a cartridge breaks off a hammer drill, the reason is a failed retaining ring at the point where the cartridge is attached to the raster bushing. The solution is simple - replace the ring.

Mechanical malfunctions of the Bosch rotary hammer

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.

How to repair a hammer drill / 2-24 / How to change the impact bolt / Drunk bearing / Maintenance / Repair

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.

Burnt rotor manifold of a Bosch rotary hammer

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 rotary hammer electric motor does not work;
there is no power to the hammer drill motor.

The brushes sparkle

Doesn't spin or drill

Failure to rotate the drive shaft occurs either due to a breakdown in the gearbox, or if something has gone wrong in the engine itself. This can be determined by ear.

When the motor is running and you can hear its humming, it means that the gearbox is not transmitting rotation to the chuck. If, after starting the tool, the motor does not hum, the power supply is interrupted. Perhaps the circuit is broken somewhere or the turns on the coils are shorted.

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What to do if it doesn’t turn under load:

How to insert a drill

Installing the drill does not require much effort and is done quite quickly:

place the element in the chuck,
turn the top part clockwise all the way,
fix.

After all the steps have been completed, it is imperative to check the fastenings and their stability so that problems do not arise during operation.

Assembly

The assembly of the device occurs in the opposite order strictly according to the list. It is recommended to first apply fresh lubricant to all parts and clean the body with gasoline. If necessary, all damaged parts are replaced with new ones.

Rotary hammer malfunctions

After a tool stops working, many users try to fix the problem themselves to save time. This is strictly not recommended, since the industry produces several types of rotary hammers:

electromagnetic - the peak beats in them due to the reciprocating movement of the core inside the coils;
electro-pneumatic - the clutch assembly transmits the shock through the air cushion to the flying piston through the impact piston.

The impact energy in the second case is five times greater, reaching 1.5 kW. In broken shanks of parts, fatigue damage begins over time, therefore, despite the air cushion, the pistons require periodic replacement. Rice. 1

There are straight, L-shaped tool bodies. The first are intended for limited spaces (niches, narrow cracks), the second - for the destruction of materials in the immediate vicinity of the working body. The cooling of engines of L-shaped models is much more efficient, so their service life is one and a half times longer than direct modifications. Professional rotary hammers are equipped with powerful electric motors, often have an L-shaped body, and are much heavier than their household counterparts. They are equipped with compensators that reduce vibrations on the tool body, electronic overheating protection systems, speed adjustments (for drilling mode), improved ventilation systems, and button locks.

Replacing motor brushes

The main sign that it is time to change the brushes is the formation of increased sparking in the area of the electric motor commutator, rapid heating of the brush holders, and a burning smell. When the brushes are not worn out, the spark can only be seen under them. Otherwise, the spark is visible throughout the entire circle of the collector.

The presence of a spark around the commutator circle with unworn brushes is a sign of bearing wear, rotor or stator insulation failure, commutator plate burnout, stator or rotor burnout.

Another sign that the stator has burned out is the presence of sparks under only one electrode. If you have a tester, you can use it to check the stator and rotor: measure the resistance on the rotor and stator one by one. If it is the same on both windings, then everything is fine with the stator. If you notice clear signs of problems with the rotor or stator in your hammer drill, you will have to take the device to a service center for repair. As for the brushes, you can change them yourself.

To get to the place where the brushes are installed, you will need to disassemble the housing in which the motor is installed, or simply remove the back cover. Opening the lid, you will see brushes secured in special holders. The photo below shows what these parts look like.

Brushes that are installed on rotary hammer motors come in 3 types.

Graphite ones are durable, but since they are very hard, their rubbing into the collector is not ideal, which negatively affects the latter.
Carbon - easily rubs into the commutator, providing good contact, but wears out quickly.
Carbon-graphite is an ideal option, since they are a mixture of 2 components that complement each other.

It is very important not to wait until the engine sparks and then change the brushes. Replacement is needed after they are worn to 1/3 of the nominal value (8 mm). Even if one brush is worn less than the other, both still need to be replaced.

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Pay attention to the condition of the spring in new brushes and the fastening of the contact. If the spring falls off while the engine is running, it will suffer significant damage. Also, if the spring is weak, then it will not be able to provide good contact.

Before changing the brushes, be sure to thoroughly clean the rotor and stator from any remaining graphite or coal dust. These parts can be cleaned using technical or medical alcohol.

Next, you should secure the electrodes in the holders and rub them into the collector. To do this, place a piece of fine-grained sandpaper on the commutator and grind the electrode in with rotational movements in different directions. The grinding continues until the contact area of the electrode is slightly rounded. This will ensure a better fit to the collector plates and, accordingly, better contact.

Causes of hammer drill failure

The operating principle of the percussion mechanism of a rotary hammer.

If the hammer drill stops working , the reasons may be as follows:

malfunction of the crank mechanism;
development of the intermediate shaft;
lack of lubrication;
wear of the clamping unit;
mechanical damage to impact elements (striker or clutch).

The hammer drill must be periodically lubricated by applying a special material instead of traditional Litol. Saving on equipment leads to intense wear of the barrel in which the bit/drill shank is located. Rice. 2

The hammer drill does not hit after a significant amount of lubricant leaks out of the gearbox due to wear of the seals and rings. Rubber parts operate in aggressive environments and extreme conditions. With a significant accumulation of dust and crumbs on their surface, the material loses its elasticity, bursts, and cracks under stress.

Diagram of the components of a hammer drill.

Violation of operating modes is dangerous for the hammer drill:

inexperienced users put undue pressure on the body in the hammer mode, forgetting that the bit works due to the force of the internal mechanism, the amplitude of the striker stroke decreases, leading to its breakage;
a change in the trajectory of the bit with some penetration of the working body into the material being destroyed leads to wear of the piston, striker, bearings, and crank assembly;
Overheating of the tool during prolonged use in difficult conditions can result in shearing of gear teeth.

A hammer drill is often used for chipping ceilings, which increases the amount of dust in the spindle. External anthers are not able to protect internal components from abrasive penetration. Tools from two or three manufacturers are equipped with internal boots (for example, the Kress PK450HM model), so periodic inspection and cleaning of the clamping unit is required.

Strong noise in the gearbox indicates wear of the gears or broken teeth; excessive heating of this unit warns of either a lack of oil or damage to the bearings.

The power tool can operate in drilling mode without a hammer, but not vice versa. If the rotation unit is damaged, chiseling becomes impossible because the internal mechanisms become jammed. In this case, urgent repairs will cost ½ – ¾ of the cost of a new tool, which is economically unprofitable for the user.

How to repair a Makita HR 2450 rotary hammer if the shock mode has disappeared

Makita power tools have long established themselves as professional, reliable and easy to maintain. In addition, it has good maintainability and a relatively low price.

Of all the lines of hammer drills, I would like to focus on the Makita HR 2450 model. The tool is very easy to use, has three operating modes and can withstand very long loads. The author of these lines worked faithfully and faithfully for more than six years without any breakdowns. Moreover, it was used under intense loads. But one fine moment...

Work process

Disassembling the hammer drill should begin by removing the protective rubber cap - boot. It can be easily removed, just grab it with your fingers and pull it off the barrel.

Then, press on the plastic cover and compress the SDS mechanism retaining spring. remove the retaining ring with a screwdriver.

The cover is removed from the barrel, and behind it, compressing the spring again, we pull out the retaining ball along with the spring and the figured washer.

After which the operating mode switch is disassembled. Under the cover that holds the red locking button, there is a special slot for a screwdriver. By inserting a screwdriver into this groove and prying the cover slightly, first from one edge and then from the other, carefully remove it. You should not apply significant effort here; the lid is still plastic and may break. The red button along with the spring is removed from the switch body, and it is moved to the left all the way, just beyond the drilling mode. It is from this position that it is removed from the gearbox. For this operation, the switch must be lightly picked up with thin screwdrivers on both sides and removed along with the rubber o-ring.

Removing the rotary hammer mode switch

Now the gear box is removed. Using a Phillips screwdriver, unscrew the four bolts connecting the box to the stator housing. Then, holding it with your hand, you need to lightly hit the end of the barrel with a mallet so that the box comes off the gearbox.

After removing the box, remove the barrel from the gearbox. It comes off easily.

Use a rag to remove old grease, wash the barrel with gasoline or kerosene and wipe dry.

So, as mentioned above, it was necessary to completely change the entire barrel. However, this item purchased at the service center turned out to be “as naked as a falcon.” That is, there was absolutely nothing on it and all the parts from the old barrel had to be moved to a new “blank”.

The most difficult operation was removing the firing pin from the barrel body. There are special holes in the barrel body through which the locking ring can be seen. This ring holds the firing pin with rings and rubber dampers in the body seat. Inserting a thin screwdriver into the hole, bend the ring slightly. We do this first on one side and then on the other. The stopper should come out of the groove.

Then, from the inside, using a homemade wire hook, we pull the stopper out into the light of day.

Using a wire hook, remove the stopper from the inside.

Next, remove the striker with washers and rubber rings. For assembly, it is necessary to remember or sketch the location of all rings and washers. If something goes wrong, photographs and drawings from the article will help.

Now you need to remove the gear from the shaft. After pressing on the washer and compressing the spring, use a thin screwdriver to remove the retaining ring from the groove. After removing it, remove the washer, spring and gear from the barrel.

The gear wheel is put on the new barrel and engaged with the splines. Next, a spring with a washer and a stopper are installed on it. You need to insert the locking ring and fix the mechanism in the working position.

To do this, take the barrel in both hands and, resting it in your palms, forcefully compress the spring with your fingers, while simultaneously moving the washer and stopper down. You need to squeeze until the stopper fits into the groove.

Then a firing pin with washers and rubber rings is installed inside the barrel in the order in which it was disassembled. But first you need to pay attention to the condition of the drummer, his appearance.

If the firing pin has gouges and pits after a long period of work or because it was scratched by a broken bushing, then it should be sanded a little. To do this, it is clamped into the drill chuck and processed with fine-grained emery cloth. But if the irregularities are too large, then the striker will be easier to replace.

READ What is the difference between Makita 2470 and 2450

It is necessary to lubricate the striker with a special lubricant before installation and then use the lubricant during operation. When inserting a drill into a hammer drill, you need to apply a little lubricant to its shank. This extends the service life of the machine.

Having installed the firing pin mechanism into the barrel, we fix it with a locking ring. Using a screwdriver, we try to move the firing pin on both sides inside the barrel. It should move easily in the channel and not jam.

We install the assembled barrel into the gearbox housing. Putting it on the cylinder with the piston, we engage it with the drive gear and insert it into the body. All parts should be well lubricated during assembly.

Then we install the gearbox, having previously lubricated the needle bearing. Using four bolts, we tighten the box to the stator housing and install the operating mode switch in place. To do this, set it in a position slightly to the left of the drilling mode. We insert the red locking button with a spring and move the switch to the drilling mode. We snap the plastic cover and check the operation of the switch.

Reinstalling the mode switch

Snap the cover of the rotary hammer mode switch

Then, as a final touch, the SDS mechanism is assembled. Having installed the mechanism spring, put on the figured washer and insert the ball. Then use a plastic cover to compress the spring of the mechanism and insert the retaining ring. Putting on the rubber boot is no longer difficult.

Compressing the spring with the washer, install the retaining ball

Let's try the hammer drill under load. When the machine is operating, there should be no extraneous noise in the gearbox; the operating mode switch should move easily without jamming. In general, everything should work as before the breakdown.

What to do if the hammer drill stops hammering uninterruptedly

Lack of preventive maintenance after 100-80 hours of operation will inevitably lead to failure of the hammer drill.

Other mechanical breakdowns and their elimination

In addition to breakdowns associated with the impact mechanism, other mechanical breakdowns may also occur in the hammer drill.

Pistol type hammer drills

The design of the impact mechanism in a pistol-type unit is slightly different from the same-purpose mechanism installed in a barrel-type unit.

Its main difference is that the piston is driven not by a connecting rod, but by a swinging (“drunk”) bearing. Therefore, the most common breakdown of this unit is the wear of a “drunk” bearing that needs to be replaced.

The next photo shows a destroyed “drunk” bearing, which is the reason why the hammer drill stopped hammering .

The swing bearing is removed using a flat screwdriver, which you need to pick up the bracket and remove it. After this, the bearing is easily separated from the gearbox housing.

When replacing a collapsed bearing, you should thoroughly rinse the gearbox, since it is in its housing that fragments of the broken part may remain.

After cleaning and installing a new bearing, apply a thick layer of lubricant to this block.

Also, the reason that the device does not hit can be a broken firing pin. To get it out, you need to remove the retaining ring that is visible in the hole.

Take a small screwdriver, pick up the ring with it, and move it to the right (towards the gear).

Do the same steps on the other side of the part. Next, insert a screwdriver into the hole in the part and push through the removed internal parts of the mechanism.

After this action, you can easily get the locking ring and the housing in which the broken striker is located.

If you disassemble this case, you will see the “culprit” of the malfunction, due to which the hammer drill does not hammer.

When assembling the impact mechanism, be sure to generously apply lubricant to all parts.

Troubleshooting Methods

Self-repair of a rotary hammer is extremely difficult due to its complex design. Even disassembling the case is often an impossible task for a home craftsman.

In addition to appropriate education, specialists from service centers of leading brands have regular work experience, the necessary tools, and equipment.

In addition, a diagnosis of a power tool is made during the initial inspection, which allows you to plan your budget: invest in an existing tool without guarantees of long-term operation, or spend money on a new power tool with a long service life and a manufacturer’s warranty.

Disassembling the rotary hammer gearbox: 1 – special ring, 2 – releasing sleeve, 3 – ring, 4 – ball, 5 – spring 8 – casing, 22 – closing spring, 28a – switch, 29 – ring, 30 – spring, 31 – latch.

The hammer drill is used in different modes, which significantly reduces the life of the working parts. In addition, specialized companies more often use either slotting (concrete, stone work, restoration of buildings, foundations) or drilling (installation of household and industrial equipment). If in the second case, following the manufacturer’s recommendations on drilling modes, you can extend the service life of the power tool, then in the first option it is very difficult to calculate the load. For example, with a specified maximum concrete drilling of 24 mm, it is recommended to use drills in the range of 18-16 mm. Peaks for breaking concrete, stone, and brick are standard, so the tool experiences different loads.

If the power tool stops hitting, you can limit yourself to disassembling the spindle assembly in the following sequence:

dismantling the mode switch lever - the parts are usually made of polymers and therefore are quite fragile;
detachment of the boot - the rubber corrugation must be periodically replaced, since it often comes into contact with destructible materials, wears out, and cracks;
with a dismountable cartridge, the brushes are first removed; screws are loosened and unscrewed;
the body is divided into two halves.

Visual inspection in 90% of cases allows you to identify a malfunction and replace the damaged/worn part. Before assembly, lubricant must be added and replaced.

Sources:

https://pro-instrument.com/ruchnoj/remont-perforatora-svoimi-rukami.html https://crast.ru/instrumenty/perforator-ne-krutit-pod-nagruzkoj https://slavasozidatelyam.ru/strojka- i-remont/pochemu-perforator-ne-bet/ https://slavasozidatelyam.ru/strojka-i-remont/ne-dolbit-perforator/ https://moiinstrumenty.ru/elektro/perforator-perestal-dolbit.html

Do-it-yourself disassembly and repair of a rotary hammer

A rotary hammer, like any electric tool, requires careful treatment, proper operation and timely preventive maintenance. If these standards are neglected, the device may fail without exhausting its service life. In case of some malfunctions, you can repair a hammer drill yourself, but to eliminate breakdowns associated with the electrical part of the engine, you will need the help of a specialist.

Removing the cartridge

Disassembling the unit for troubleshooting should be carried out carefully, inspecting each removed part. To make assembly easier, it is better to photograph the disassembly process. If you do not find any external defects on the device, then it is recommended to start disassembling it with the cartridge.

First, remove the boot (1), made of rubber.
Carefully, so as not to lose it, use a screwdriver to remove the retaining ring (2) and then the plastic boot (3).
At the next stage, it is important not to lose the small ball that is located under the washer (4). Remove the washer (4), plate (5) and spring (6), as well as the ball (7). It is when these parts wear out that the drill falls out of the chuck. Some cartridge models may have additional balls and washers.

Helical gears

The reason that the device stopped working normally, namely, stopped drilling and chiseling , may lie in worn-out teeth on the rotor shaft.

If this happens, the teeth on the intermediate helical gear will also be worn.

This problem occurs when the tool is jammed or the clutch is malfunctioning. The breakdown is eliminated by replacing the intermediate gear and engine rotor.