How To Disassemble Gearbox Angle Grinder

Replacing the gearbox bearing of the angle grinder Some units of the angle grinder take on increased loads, so they often wear out and fail. On how to replace the gearbox bearing of the angle grinder Bosch, Makita, Hitachi, Sparky, Interskol, are presented in this article.


Successful repair of bearing assemblies will help compliance with the following recommendations.

  • It is necessary know the design of the operated angle grinder. Study the technical documentation supplied with your angle grinder. Knowing the location of assemblies and parts will help to correctly disassemble and assemble the angle grinder during repair.
  • It will help to perform work on replacing bearings availability of the required tools for this. This tool is not complicated and is almost always available in the arsenal of home craftsmen: screwdrivers, wrenches, hammers, a set of pullers or other hand tools (vices, extensions, drifts of various designs) for fixing and removing bearings.
  • When repairing grinders there is a certain order of work. You should adhere to it, taking into account some differences associated with the features of a particular model.
  • Replace bearings with even slight shaft runout, since a damaged bearing can completely damage the entire power tool.
  • Before carrying out repair work, make sure that the power tool is unplugged power supply.
how to disassemble gearbox angle grinder

Open bearing for Hammer angle grinder. Photo 220V

The tool used must be in good condition:

  • The structural elements of the pullers (legs, rods, stops, screw devices) comply with the technical documentation;
  • Screwdrivers have smooth side edges, a straight rod is securely fixed in the handle;
  • Wrench jaws are parallel, do not have cracks or nicks;
  • The hammers are securely mounted on the handles.

Compliance with these recommendations will allow you to properly and safely disassemble the angle grinder, replace defective bearings, re-lubricate all parts and assemble the angle grinder for its further operation.


One of the Makita models describes the process of replacing bearings without the use of special tools, by any available means at hand. As reference surfaces wooden blocks are used from hard rocks, which take on the load when performing various technological operations using force.

Used as accessories suitable thickness metal sheets and sockets (suitable pipes can be used) when knocking out bearings. The shaft centering holes serve as a base for a sharpened rod (this is a modified old screwdriver), with which the shaft itself is released. The only industrial production tool is circlip remover, although without it, you can figure out how to remove them with the help of improvised means.


The following describes replacement of gearbox bearings of one of the Bosch models, which has a large backlash on the spindle. Here, the main actuator creating the push-in / push-in forces are ordinary locksmith vice. The use of various extensions in the form of pipes of appropriate sizes and other similar parts allows the transfer of forces to the desired place in the structure using the movement of the vise jaws. Some operations are performed with the help of extensions and light hammer blows.

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The design feature is plastic-filled flange. To press out / press in the flange bearing, the author removed the plastic interfering with this process with a knife and a torch. Perhaps, if you have the skills of a turner, just cut this material on a lathe.

How to disassemble an angle grinder

Intensive operation of the angle grinder (angle grinder), which is so popular and in demand in everyday life, necessarily leads to the need to repair it. But, most skilled people in such a situation run into the question of how to disassemble an angle grinder so as not to cause great damage. Only knowledge of the device and the principles of disassembly, repair of the device allows you to independently carry out the repair in a qualified manner.

Constructive modifications of grinders

The angle grinder is very different in several design features:

  • Power is the basis of all design features: the bearings used, the type of transmission and hardness of the metals used, the build quality and the materials used in the design.
  • Hull assembly features. The transmission mechanism is necessarily located in a metal case, which, despite the general principles of assembly, can have various modifications. In most cases, the movement housing has a cover with four lag bolts or screws. It is worth considering that before disassembling the gearbox of the angle grinder, it is necessary to carefully visually examine the assembly seams of the case, showing the details of the structure, i.E. Which must be disassembled first.
  • The quality of the materials used for the assembly of the angle grinder varies greatly from the manufacturer itself, therefore the celebrity and the availability of branded spare parts speaks of the quality of the device itself and its repairability.

Component parts of angle grinder

To know, how to disassemble an angle grinder, it is necessary to clearly understand its design features, places and features of the connection of parts:

  • A common body with a handle is usually made of plastic and has two halves connected by self-tapping screws along the perimeter. Unscrewing it allows access to the electric motor and all electrical components. Many models have a non-separable part of the case, in which the stator coils are mounted, and the entire device is disassembled by unscrewing the side covers.
  • The angle grinder motor is fixed in the cushions of the housing, and its notch reveals an unobstructed recess of the rotor from the stator. The engine bearings are also quite easy to insert into the housing, but their fit on the shaft has a large interference, which very often becomes a problem in the situation of disassembling an angle grinder.
  • Rotor. Not a collapsible unit for self-repair, so you need to be careful with it so as not to damage the winding wires, the armature and the geometric shapes of the metal components.
  • The stator is an electrical winding with a transformer steel housing. Self-repair of the angle grinder unit is not possible.
  • The shank of the rotor with the transmission teeth goes into the metal housing of the gearbox, in which the bearing can be securely fixed, and removing it without tools using an impact force can lead to cracking of the aluminum.
  • The problem of how to disassemble an angle grinder gearbox is found mainly in only one of its assembly, the fastening of the driven gear on the output shaft and extrusion of the assembly from the removable housing cover.
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The reason high noise angle grinder Diold the author found out in the following. After dismantling the gearbox large backlash was found in the bearing units. It should be noted that they did not affect the quality of the gear teeth in any way; they are in good working order. That is, if the gears are made of high-quality material in compliance with heat treatment technology, they can work reliably in the most difficult conditions. With the help of the tool necessary for such repair work, the author shows how replace defective bearings.

Jammed spindle in model DWT angle grinder, which is described in the following, repaired according to well-established technology. Detached from the rotor of the brushes, so as not to damage them in further repair actions, the reducer is disassembled. After that, the wear of the gears and the play of the bearing assemblies are visually checked.

In this particular case, it is a failed bearing caused a malfunction Angle Grinder. In it is shown how one faulty bearing can lead to a whole train of broken other parts. You should carefully monitor the condition of the bearing assemblies, regularly check for backlash.


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

The elements

The angle grinder converts electrical energy into a mechanical action of the tool on the workpiece. Therefore, its construction consists electrical and mechanical. The bevel gearbox is just the main element of the mechanical part of the angle grinder. It includes the following nodes and details:

  • Gear case;
  • The spindle on which the working tool is located;
  • A leading bevel gear located on the rotor of the electric motor;
  • Driven bevel gear located on the spindle;
  • Rolling and plain bearings, which act as supports for the transmission of rotation.
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Gear reducer

Four bolts hold it. They must be unscrewed and with the utmost care remove the gearbox from the housing of the angle grinder. Disassembling the gearbox is necessary to clean it and replace worn parts. This is one of the most important components of an angle grinder, which undergoes enormous stress during operation.

It includes:

  • Body;
  • Large gear;
  • Driven gear;
  • Bearing. It must be lubricated to reduce the friction force.

To remove the rotor from the gearbox housing, it is necessary to unscrew the nut that holds the rotor. Remove the rotor with a special puller. Such an operation is associated with some difficulties, therefore, if there are no special skills, it is better to provide such work to professionals. You can’t do without a puller here.

I must say that for simple removal of dirt, such a detailed disassembly is not required. It is only needed to replace a worn out bearing or a worn out rotor.

This operation will require some effort. Removing the anchor from the case must be done very carefully, as it breaks easily.

When during operation there is strong sparking, a large heating of the case, you just need to get the armature to clean the collector. The device will be ready for use again.

How to disassemble the gearbox correctly: recommendations

When the gearbox completely refuses to work, it requires complete disassembly for replacement parts and thorough cleaning. To carry out the work, you need to prepare a locksmith vice. All works are performed in a specific technological sequence:

  1. A wrench is used to unscrew the bolt holding the gearbox housing.
  2. The rotor body is clamped in a vice with great care.
  3. Making light blows with a hammer, the body is removed.
  4. The rotor is in a convenient position to remove the bearing. The vice is clamped again.

By placing a wooden block, the bearing is knocked out. To remove the gear from the gearbox axis, you must:

  1. Wrap the rotor with a rag and secure with a vice jaws.
  2. The gear is also wrapped in rags, using a gas wrench, turn it counterclockwise.

Main modules used

  1. The body is usually made of special impact resistant plastic.
  2. Powerful electric motor.
  3. High quality reducer.
  4. Smooth start.
  5. Electric motor switch.
  6. SJS system. The presence of the system allows the tool to run smoothly without jumps. In addition, it turns off the angle grinder in the event of a jammed disc, minimizing vibration. It saves the operator from serious injury.
  7. Protective cover.
  8. Additional handle. It can be used to hold the angle grinder while working. This handle can be set in a wide variety of positions, giving the tool versatility.