It is difficult to imagine the life of a modern person without the use of electric machines. They have firmly entered our life, these are devices that help in the household and in the kitchen - combines, meat grinders, etc., and screwdrivers, drills and other power tools are used in workshops. In household and industrial appliances, it is often used collector motor. During its operation, the wear of the brush-collector assembly occurs. To repair this unit, you need to understand the marking of electric motor brushes, which we will discuss in this article.
Content:
- Purpose of the brush assembly
- Classification and labeling
- What are the criteria for choosing brushes
- Decoding of marking
Purpose of the brush assembly
The brush-collector unit is designed to transmit electricity to the windings of the rotating armature. In it, brushes act as a movable sliding contact, which wear out due to high friction and high speed of the electric motor. Therefore, special requirements are imposed on the material from which they are made. It is selected in such a way that there is no overheating at the point of contact.
Electric brushes are used not only on collector motors, but also on synchronous machines and asynchronous motors with a phase rotor, where copper rings are installed instead of the collector.
They must provide:
- Reliable connection with collector lamellas or rings, while sparking and the risk of shorting the windings should be minimized.
- The smallest resistance at the point of contact of the sliding type.
- Friction resistant. The wear resistance of the material should ensure its serviceability for a long time.
Classification and labeling
The industry produces different types of electric brushes. They are subdivided according to operating conditions:
- Carbon-graphite, have low strength, are used in devices with low mechanical stress. The marking is G21, G22.
- Graphite. They are made of graphite filled with carbon black or other substances. Provide switching of small currents in generators and motors. Marking G20, EG61A is used. The Korean company has mastered and patented graphite brushes with the designation KPNG, which have an increased service life, which increases the reliability of the equipment and increases the turnaround time.
- Electrographite - have increased mechanical strength. During manufacture, the material is saturated with carbon. Provide switching of currents of large magnitude. The brands EG, EG74, EG2A, EG14, EG841, etc. are produced.
- Copper-graphite (metal-graphite). The composition of the brushes includes a filler of copper, silver, tin and graphite powder. They have great strength, resistant to gassed and liquid media. They are used for switching in conditions of medium and high complexity. Marking is used MG, MGS, MGS, MGS20, MGS51, MGSO, MGSO1M, M1A, M1.
What are the criteria for choosing brushes
Based on the current GOST 12232-89, according to which the industry produces brushes installed in an electric motor, you can select the required product.
To choose them correctly, you need to know the parameters:
- The material from which the contact is made (brush brand).
- Dimensions: depth, width, length. Moreover, the length may have slight differences in the direction of increasing or decreasing.
- Part execution (configuration or type). Determine the version - with a conductor or not, where it should be attached, what material it is made of and what the tip for connection should be (ring or "plug", etc.).
This information is presented in the appropriate manuals for engines or marking of their components. Below, as a sample, only a small part of the table is presented. According to this information, the selection of graphite brushes by size and lead-out conductors is made.
Decoding of marking
Domestic marking of brushes for electric motors includes full information about the product, for example:
EG-14 20 * 32 * 40 K1-3
The decoding of the brush marking will look like this:
- EG-14 - the material from which the brush is made;
- 20 * 32 * 40 - dimensions;
- K1-3 - configuration (determined from the table).
At the same time, the reference books contain additional information, where the parameters for each type of brushes are indicated.
According to the information on the purpose and dimensions in the reference books, you can pick up brushes for the power tool, which uses the collector motor. It should be borne in mind that they have different markings.
For a hammer drill, drill, mixer and grinder, there can be either the same or different brands of brushes, since these devices have different loads and revolutions. This must be taken into account when replacing, and not chosen only by size.
If the engine has special features in the design, you can specify the required parameters when ordering:
- The number of current-carrying conductors, as well as their length and cross-section.
- The configuration of the connection contact and overlay.
Often, manufacturers of power tools provide a table of brands or catalog numbers, in which they display information about which brush is suitable for which device. Below is a compliance table for the Makita power tool, which indicates the type of tool and the marking of the installed brushes.
The following two tables will help you to choose the right accessories for your Bosch power tool motors. In the upper column, the types of brushes are indicated with markings by numbers (# 1, # 2, # 3... # 15) and their catalog numbers, the vertical columns indicate the models of the power tool and also their numbers.
When selecting, it is necessary to have an idea of what is the difference between coal and graphite and other types of electric brushes. Incorrectly selected components can lead to the failure of the collector, and the electric motor will quickly become unusable or simply newly installed parts will quickly wear off.
Now you know what markings for motor brushes exist and how to choose the right electric brushes for the right tool. We hope the information provided was useful and interesting for you!
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