Why does not hammer hammer, but only drills

The hammer drill slips

The reason for this is a loose coupling. It is enough to tighten it or replace it.

Reverse does not work

The reason is the breakdown of the mode switch button. Disassemble the back panel and, if necessary, replace the contacts.

The punch of the cause is heated

Every tool needs timely maintenance, and the hammer drill needs it first. After all, the work of this tool is accompanied by a huge number of reciprocating rotations and movements, and the volume of dust emitted from the working object has a high concentration. Under these operating conditions, careful maintenance of the device and timely replacement of the lubricant in the perforator gearbox are required.

Most users believe that if grease is present, it can be used indefinitely. This opinion usually exists among users due to the poor level of knowledge of the laws of physics, therefore, we will tell you about the mechanism of lubrication in more detail.

How to disassemble and check the gearbox: how to remove the plastic case, take out the “drunk bearing” and other elements

In order to determine the malfunction of the gearbox, it must be completely disassembled. For this, the plastic housing is removed, the gearbox is thoroughly cleaned of old grease. Disconnect from the gearbox housing:

  • floating bearing;
  • drive gear shaft;
  • raster sleeve;
  • sleeve with piston.

The floating bearing, also referred to as “drunken bearing”, is attached to the aluminum housing of the gearbox with a bracket that must be wrung out with a flat screwdriver. The released bearing is removed and replaced if necessary. In addition, you should pay attention to the fact that inside the “drunken bearing” there is a needle bearing on which the drive gear rotates. When the hammer drill operates in the impact mode, it experiences heavy loads, and therefore often fails. A new bearing is purchased separately or assembled with an overhead shaft.

The grid sleeve contains an impact bolt that is secured internally with a metal retaining ring. On the sides of the sleeve there are two technological holes through which the locking mechanism is accessed. After releasing the ring fixing, the impact bolt freely falls out of the bushing. Inside it is directly a striker made of high-alloy steel.

When repairing or replacing the impact bolt, it is also necessary to replace the sealing rubber bushings, which ensure the tightness of the mechanism. All parts of the striker are subject to abundant lubrication with special grease.

There is another needle bearing in the plastic casing of the gearbox at the outlet of the hub bushing, which must be well lubricated.

Why does the drill spark?

The causes of sparking can be: contamination of the collector contacts, ingress of graphite particles between the contacts of the collectors, short circuits in the armature winding.

does, hammer, only, drills

How to replace the cartridge

In most cases, the cartridge can be repaired. If the wear of individual parts has exceeded the permissible limits or if the rubber boot and plastic skirt are damaged, it is more advisable to replace the entire chuck.

The procedure for replacing the cartridge is clear from the above procedure for disassembling the punch.

The hammer drill does not spin or drill

If the chuck does not rotate when the start button is pressed, the cause can be identified by the sound beforehand. If the electric motor hums, but does not turn the chuck, most likely something is preventing the rotor from rotating inside the gearbox. What happened to the engine, you will have to find out by disassembling the mechanical part of the tool.

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If the engine does not hum when you turn it on, it is more likely that the engine has broken down. Having opened the lid of the device, it is necessary to determine what exactly led to this phenomenon. This may be an open circuit in the power supply, a breakdown of the start button, or a short circuit in the windings of the coils. The tester identifies the specific cause and repairs it accordingly.

If the hammer drill hits but does not drill

  • The conical spring holds the clutch, if it looses, a problem may arise;
  • The lock roller has stopped fixing the large shaft gear;
  • The tool holder stops working in the barrel.

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

The cylinder, the striker, the barrel striker of the percussion mechanism collapsed

There are times when the drummer bites into the cylinder, pos. 26, which leads to the destruction of the cylinder and the impossibility of creating air pressure in the barrel of the impact mechanism. And the second reason: destruction or breakage of the striker pos. 28, leading to the curvature of the part and the impossibility of transmitting the shock impulse.
Breakdowns are eliminated by complete replacement of failed parts.

The striker is jammed in the piston, the destruction of the piston

The lock roller does not lock the large barrel shaft gear

The large gear wheel, pos. 22, is mounted on the shaft of the barrel, pos. 01, by the roller, pos. 88, pressed against the shoulder of the shaft by a conical spring, pos. 80, and fixed with a retaining ring, pos. 85.

The reason may be a weakening of the force of the conical spring, pos. 80, destruction of the retaining ring, pos. 85, falling out of the fixing roller, pos. 88.

Gear wheel pos. 22 on the shaft pos. 01 of the barrel pos. 821 of the shock block assembly

The hammer drill motor does not work

The reasons for a not working electric motor can be:

  • short circuit in the rotor, stator;
  • destruction of coal electric brushes;
  • weakening of the fastening of the brush holders;
  • burnout of lamellas on the rotor manifold;
  • breakage of the rotor or stator windings.

The listed malfunctions are eliminated by repair (rewinding the winding manually, replacing the collector and unsoldering the winding leads) or replacing the rotor, stator, carbon electric brushes with new ones.
The main part of the malfunctions of the electrical part of the Bosch 2-26 rotary hammer is 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.

Burnt manifold of the rotor of the Bosch rotary hammer

Collapsed rolling bearing race (drunk bearing)

When the drunk bearing, pos. 830 is destroyed, the rotary movement of the intermediate shaft cannot be converted into the translational movement of the cylinder in the percussion mechanism.

Eliminated by completely replacing the rolling bearing.

Friction bearing

The hammer drill stops hammering, but drills

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

  • the rubber rings of the striker, striker, piston are worn out;
  • the rolling bearing cage collapsed;
  • the cylinder collapsed, the firing pin of the barrel of the percussion mechanism;
  • cut the splines of the clutch mounted on the intermediate shaft;

Consider the options in which the hammer drill does not drill or chisel

Consider the options in which the hammer drill drills, but does not hammer

“Drunk” bearing

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

Mode switch

Mechanism parts may come out of the guide grooves. This may be due to deformation, wear, or frequent use of the tool in an incomplete mode. The malfunction is eliminated by installing parts in their places or replacing them with new ones.

Reasons for not hitting

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

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Causes and possibilities of elimination of the problem when there is no hammer blow

When drilling holes with a hammer drill, the main factor is not the rotation of the drill, but the impact. Its strength determines both the drilling speed and the ability of the tool to cope with particularly hard building materials (concrete, granite, etc.).

Dust and constant stress on the tool adversely affect its performance. During operation, the impact force may noticeably decrease or disappear altogether.

How does a hammer drill work and why it “refuses” to hammer?

Hammer hammer mechanism

Most modern rock drills have an electro-pneumatic impact mechanism. “Electro”. because the mechanics are driven by an electric motor, and “pneumatic” means that the firing pin striking the drill shank is driven by air.

  • Gear wheel for transferring rotation from the engine
  • “Drunk” bearing
  • Piston
  • Drummer (“flying piston”)
  • Trunk
  • Striker
  • SDS cartridge

When the button is pressed, the engine transfers rotation to the shaft with the “drunken” bearing, which in turn drives the piston inside the barrel. When 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 whole cycle is repeated.

Most rock drills have two or three modes of operation:

  • 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 mixer for preparing building mixtures.


Failure to change the grease can also be the reason for the lack of impact. Working with a hammer drill implies the presence of dust, which does not in the best way affect the properties of lubricants. Dust can clog the holes in the cylinder that allow air to circulate when the hammer is operating. The same effect is possible when using a grease that is too thick, not intended for rock drills.

Striker and drummer

These parts are made from high strength steel. The striker rarely fails, but the bushing in which it moves absorbs some of the shock energy and collapses over time. Shrapnel jam the firing pin, and the hammer stops hitting.

The striker (“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 striker. The more wear and tear, 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 against the firing pin. This is usually the result of pressure on the rock drill while drilling holes. The drilling speed does not increase, but the load on the mechanism increases, which accelerates wear. Repair consists in chamfering on an emery machine or replacing a part.

What to do if there is no impact in the hammer drill

If the tool refuses to hammer, it is not necessary to immediately disassemble it or plan a trip to the service. Sometimes the reasons for refusal can be elementary.

In some models of hammer drills, the impact mode is blocked by reverse. It is enough to move the lever to the desired position. A similar effect can be from not fully turned the mode switch.

Sealing Solutions for Hammer Drills and Demolition Hammers – Freudenberg Sealing Technologies

When drilling vertically, dust and small debris can clog the chuck and firing pin under the drill. Having taken out the drill, it is necessary to clean the cartridge of debris and push the firing pin down.

Using cheap consumables can also cause malfunction. The shank of a low-quality drill sometimes turns out to be riveted in the form of a “fungus” inside the chuck. It is not always possible to extract such a drill without disassembling the cartridge.

High-quality consumables, timely prevention and maintenance are guaranteed to exclude tool failure at the most inopportune moment. If there are hints of a malfunction, it is better to immediately contact the service or, if you have experience, make repairs yourself.

Cut off the splines of the clutch poz.67 installed on the intermediate shaft

The malfunction is eliminated by repairing the clutch or completely replacing it.
During repairs, worn-out teeth are filed on the clutch. To correct this defect, a round file and a drill are used. The clutch is clamped in the hand, and the tooth profiles are straightened with a drill with an appropriate file. The splines on the intermediate shaft are also being modified in the same way.

Restoration of the teeth of the intermediate shaft clutch

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The force of the conical spring pressing the clutch has weakened

When the spring pressure (pos. 50) decreases, the clutch slips on the intermediate shaft, without transferring rotation from the small spur gear to the large gear (pos. 22) of the barrel shaft, pos. 821, of the percussion mechanism. By the way, on different Bosch models the clutches are arranged differently.

Details of the unit for transmitting the torque and translational impulse

How to remove the mode switch

To diagnose internal components, it is necessary to remove the punch body and clean the surface of the components from dust. Parsing begins with the separation of the operating mode regulator.

It is moved all the way. as a rule, this is the extreme right position (below the bump mode icon), after which, prying it with a flat screwdriver, remove the regulator from its socket.

Daily care and storage

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

  • run the device “idle” before starting work. If the perforator shows signs of a breakdown, work is stopped and diagnostics are started.
  • After completing the work, take care of the cleanliness of the punch. it is important to remember electrical appliances “do not like” water, cleaning is carried out with a vacuum cleaner and rags.
  • If the hammer drill works in cold weather or is moved indoors from the street, do not start it right away. Let the nodes “warm up” and thaw the grease.
  • Carry the hammer drill in a special box or suitcase (usually included) to avoid dust and debris.

Thus, if you follow the objective precautions and operating rules of the hammer drill, it will last a long time and without breakdowns. If the trouble nevertheless happened. the proposed advice of the masters will help determine the essence of the problem and eliminate the breakdown in a timely manner.

Nothing is eternal. And the most reliable Bosch rock drills start to break over time. But any malfunction can be repaired by hand if you have a detailed guide on how to carry out repair work. Below we offer you a guide to troubleshooting Bosch rotary hammer drills and how to fix them.
The main reasons for the occurrence of breakdowns are:

  • careless work with the tool;
  • improper storage of the punch;
  • heavy loads when working on working bodies when chiselling or drilling;
  • overheating of the tool;
  • long-term work without interruption;
  • failure to comply with maintenance deadlines.

Conditionally, faults can be divided into mechanical and electrical.

Next, we will consider the faults by their belonging, dividing them into mechanical and electrical faults.

Removing the cartridge

After making sure that the perforator is de-energized, the installed nozzle is removed from the cartridge head, after which the cartridge is separated and disassembled. For this:

  • Use a flat screwdriver to detach the rubber boot.
  • Using pliers, open and remove the retaining ring.
  • Carefully separate the plastic anti-invasive sheathing tube, making sure that the bearing balls, washer and spring do not fall out.
  • Parts are laid out and cleaned of grease, after which they are inspected for damage.

Reference. In a situation where the installed nozzle is jammed in the cam mechanism of the chuck, it is recommended to tap it in a circle with a rubber hammer, and then pour in 5-7 drops of liquid lubricant. The operation is carried out 2-3 times with a break of 3 minutes, after which the nozzle (chisel or spatula) is removed with pliers.

Cut off teeth on the small rotor gear

There is a rotation of the gears with cutting teeth on one of them, more often on a small.

does, hammer, only, drills

When the working tool is jammed and the clutch does not work properly, there is wear or complete destruction of the gear teeth on the perforator shaft and the intermediate shaft.

In this case, the rotor or the large gear of the intermediate shaft changes completely.

Rotary hammer bosch 2-26 with cut splines

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Possible malfunctions

The following are the main signs that indicate malfunctions of the perforator units and how to fix them with your own hands.

Does not hold a cartridge

If the raster sleeve stops holding the chuck while the hammer is in operation, the cause is most likely in the retaining ring. It can open or become unusable due to intense load. it is replaced with pliers and a screwdriver.