Replacing the brushes in the trimmer

Grass trimmer motor repair with my own hands

The problem occurred unexpectedly at the most inopportune moment. After prolonged warm rains, the grass in the garden and on the lawns of the summer house had grown immensely, and I had to mow it. I had to take up the trimmer for the grass. Plugged it into the electrical outlet through the extension cord and it started to work.

The motor suddenly cut out after a short period of time. Checked the voltage on the extension cord: everything is normal. Took the grass trimmer in hand and started mowing. It quickly failed again.

Lasted several times. I had to examine the wires of the extension cord and check the power. No fault found. Concluded that the failure was in the trimmer. You need to look for it.

Tools for repair

Screwdrivers and an old tester with wires and a soldering iron were needed for the work.

I had my camera and managed to take photos of all the actions to restore the motor performance. I inserted these photos into the text of the article.

Circuit Wire tapping

To check the electric circuits it is necessary to. At my country house I have an old Ts4324 device for such purposes. Its current measurement circuit is powered by nickel cadmium batteries.

After long storage, they were in discharged condition, and used since 1994, when I bought them at a garage sale. There was no chance to use them.

Power to the tester

The technical solution was suggested by an old cell phone. Engaged his battery for voltage supply, having previously checked it with the same device in the voltmeter mode.

I took out the old batteries and connected the power with thin wires of different colors directly to the leads of the tester, respecting the polarity. Used soldering iron and duct tape for connection.


Here I had no problem. The power of the cell phone battery was quite enough for the measurements and calibration.

I set the switches of the tester to the “Ohmmeter” position and used the potentiometer handle to set the pointer of the pointer to zero. I did not adjust the mechanical balancer of the pointer, it was fine before.

Prepared the tester for resistance measurements on ohms divisions.


The electric motor housing was fastened with self-tapping screws with medium-sized Phillips heads. Under them an old screwdriver from the Soviet times suited satisfactorily and a good coverage of edges was created by the head from the set of tools bought in the Internet store.

But the short working body of the combination screwdriver did not allow to work in deep notches. All hard-to-reach places are inaccessible to her. The pictures of the screwdrivers are shown in the following pictures.

The process of making the nozzle

To make the nozzle, you need to remove the handles from the carpet brushes. They can be cut with a hacksaw for metal, but it is smoother and faster to do it with a heated torch knife. It cuts them like butter.

Next, you need to screw the brushes on the blade of the grass trimmer knife, using 2 fasteners on each. It is important that after finishing it retains the balance. For this purpose it is necessary to install the brushes mounts with observance of symmetry. On each beam a marking is made for 2 holes. The distance between them should be less than the length of the brushes.

After drilling the knife, you need to put a brush to one of the beams and after measuring drill holes in it for fasteners. Further, since everything is drilled symmetrically on the knife, the remaining brushes are drilled using the previous one as a template.

Use self-tapping screws with metal drill bit to screw the brushes to the knife. It must be screwed on the bristle side. Instead of screws you can use bolts with a nut and a lock nut.

After installing the nozzle on the trimmer for grass to attach to his boom bent at the edge of the tube for water supply to the brushes.

This can be done with a gas torch or a construction hairdryer. The tube should reach the handle of the grass trimmer. On this side its edge is also bent, but by 15-20 degrees. The bent tube is attached to the trimmer rod with duct tape. This will allow it to be quickly removed after work.

brushes, trimmer

On the edge of the pipe on the handle side, you will wrap the tape and put on a garden hose. It is fixed with a clamp for safety. After that, the grass trimmer is started and the water supply is opened at a low pressure.

Before you start working with the nozzle you should first soak the surface, and then treat it with brushes. After scraping off the dried mud, if you are washing concrete or paving tiles, you should hose everything down to drive away the dirty water.

What to do if the engine does not start?

If the lawnmower fails to start, the first thing to do is check the fuel level in the tank. For fuelling your power tool it is recommended to use quality gasoline that has been purchased at a gas station and whose brand name should not be lower than AI-92. Saving on cheap fuel can break the cylinder and piston assembly, which can cost you a third of the value of the brushcutter. It is equally important to properly prepare a fuel mixture of gasoline and oil. For the proportions of these blending components, see the mower manufacturer’s instruction manual. It is not recommended to mix large quantities of gasoline, because its properties will be lost during long storage. It is better to use a freshly made mixture.

When preparing the fuel mixture, oil is poured into the gasoline with a medical syringe, allowing you to exactly observe the required proportion of components

A dirty fuel filter in the tank can also prevent the lawnmower engine from working. So if you have any problems with starting the engine, check the condition of the filter. If necessary, replace the filter. Do not leave the fuel filter at the inlet without the fuel filter.

The air filter also needs to be checked. If dirty, the part is removed, washed in gasoline in the field and put back in place. In the cottage or at home the filter can be washed in water, using a detergent. After that, rinse, squeeze, and dry the filter. The dried filter is moistened with a small amount of oil used for preparation of the fuel mixture. Excess oil is removed by squeezing the filter by hand. The part is then reassembled. Replace the cover and fasten it with the screws.

The air filter, washed in fuel mixture, squeezed and dried, is installed in place in a plastic housing and closed with a cover

How this procedure is done in more detail you can look at

If all the above procedures are performed, and the engine does not start, then adjust its idle speed by tightening the carburetor screw. In the video, placed at the beginning of the article, attention is paid to this issue.

Tips on how to quickly start the unit

Some with such force yank the handle, that we have to make repairs of the starter lawnmower with their own hands. It is possible only in the case of a broken cable or broken cable handle. In other cases, it is recommended to replace the starter. This unit is sold as a complete unit.

Bosch grass trimmer repair with their own hands

In detail: Bosch grass trimmer repair with your own hands from the real master for the site

Electric grass trimmer as well as any electric tool has a limited life. As the intensity of use increases, for various reasons, the tool’s working life decreases.

You should be prepared that at any moment during operation the lawnmower might break, but this can be avoided by regular disassembly, inspection and revision of all the important elements of the lawnmower.

Troubleshooting can be very diverse, it may be a breakdown on the electrical part of the engine and wiring, as well as on the mechanical part.

In most cases, to repair the trimmer or grass mower is not difficult, and you can do it yourself when there is a minimum of tools and basic concepts of technology. Well and for the readers of the site I will reveal the main faults and secrets for fast and reliable repair of your electric braid, consider an example of repair of electric Bosch and Gardener.

The design of most electric scythes is not a complicated device, the basic components, whether it be a trimmer for grass or grass scythes, there is an electric motor, power cord, button with capacitor, spool with a line which is mounted on the motor shaft or more complex mechanical options scythes where torque from the engine is transferred to the spool through a flexible shaft, but among the electric options scythes this option is rare.

To identify faults in the electrical part, usually not enough just one inspection, you need a multimeter, or at least a tester with a piercing. Such faults are characterized, as a rule, by complete inoperability of the motor, strong overheating or jerky operation.

brushes, trimmer

Start with the power cord and if it is damaged it can be repaired or replaced. The express check involves checking the voltage of 220 volts on the motor terminals.

The voltage should appear when you press the button, if the voltage is present then you can safely say that the grass trimmer motor is defective, it must be disconnected and carefully inspected. If the collector plates and brushes are dirty it is ok, but better to clean them with a soft cloth wetted with alcohol, if the brushes are visibly worn out they need to be replaced.

Using a multimeter in the resistance test mode (the lowest limit. ohms) stylus touch the contacts of the brushes or the graphite brushes themselves, the tester should show a resistance of no more than 100 ohms.

If the resistance is infinite (one on the multimeter) try to turn the motor shaft without removing the feeler gauges. In an operating motor resistance will be about 10. 40 ohms, if the brush does not ping then there is no contact or integrity of the windings of the stator is broken, breakage or burnout is possible. If the resistance is less than 5 ohms, there is an inter-web circuit, most likely caused by severe overheating of the motor.

To determine the specific cause of motor failure when the motor brushes do not call out, you can resort to the following procedure. The graphite brushes should be pulled out by first removing the brass inserts or by removing the clamping springs.

Collector motors in the data devices so are arranged that the windings of the stator and rotor are connected in series, and in expensive models of motors in this serial circuit is also connected and the thermostat (110 degrees), such a relay in normal circumstances keeps the power contact closed. A separate diagnostic method is to check the resistance on the collector drum plates.

To find the culprit, you need to remove the insulation in the form of clamps with fluoroplastic, where the windings and thermo-relay are connected and probe with a multimeter to each winding separately, as well as the thermo-relay.

brushes, trimmer

The most mechanically stressed parts of an electric brushcutter are the bearings and the trimmer shaft (the bobbin). In most cases, the device ceases to mow grass due to failure of its spool of fishing line

The line for your trimmer has run out. According to the instructions, rewind the line for the trimmer on the spool.

The line for the trimmer is tangled. If the spool is undamaged, you need to cut or unwind the line for the trimmer and, if necessary, rewind the entire spool.

The line for the trimmer is sticking. Because of the rather intensive work and high overheating, the plastic filaments of the fishing line can fuse with each other. You need to rewind the spool of new fishing line and inspect the damage to the bobbin itself.

The engine runs, but the spool with the fishing line does not rotate. Most likely there has been damage to the line spool. Places for fixing the bottom of the spool can break, you need to completely disassemble the bobbin and if necessary to finalize the mount or replace it at all. In most electric trimmers bobbin is simply pressed by its plastic body on the motor shaft and at high overheating, when the plastic melts, it can turn and even fly off.

Makita grass trimmer repair with your own hands

In detail: Makita grass trimmer repair with their own hands from the real master for the site

An indispensable tool of the modern gardener or owner of a private home is a lawn mower, which allows you to effectively and efficiently bring the adjacent territory in order. The brushcutter is in active use in late spring, until October. Modern units are equipped with a powerful and durable engine, reinforced transmission and basic units. Despite this, physical wear, manufacturing defects or improper use leads to the failure of the trimmer for grass. In order to make repairs trimmer for grass with your own hands need to have at least basic knowledge in the field of technology and a little experience in its repair.

The main component of any gasoline-powered tool is the internal combustion engine (ICE), which transmits the torque to the actuator by various means. In modern gasoline mowers as a part of the transmission element between the motor and the trimmer head is used duralumin rod (pipe), inside which is located the drive shaft.

Thanks to the high-speed engine, the rotation speed of the line can be up to 13 thousand revolutions per minute, depending on the manufacturer of the grasshopper. In order to prevent mechanical and thermal damage to the gearbox, the housing has a hole for grease in the form of an ointment. All brushcutter models have a sturdy shoulder strap for easy daily use.

Regardless of the manufacturer, almost every model comes with a fishing line and steel blades.

The PVC cross-section of the brushcutter line for grass trimmers varies from 1.5 to 3.0 mm.

Constructed of tough polymer it is subject to heavy wear and tear while mowing and consequently to breakage. So from time to time you need to check the presence of fishing line in the head, and if necessary make its replacement. It is recommended to buy an extra bobbin to quickly replace it with a spool of fishing line that has run out.

Presented on the market today grass trimmers with an engine are equipped with D-shaped, U-shaped or T-shaped handles, which are the main controls of the unit. For example, the throttle key and the stop/start toggle switch are on the right handle of a U-handle scythe. In the D-handle design, the throttle adjustment key is placed directly on the boom.

Due to the presence of many nodes and parts, the grass trimmer repair with their own hands involves the elimination of failures that prevent its normal operation. It should be noted the most basic malfunctions of gasoline mowers:

  • Grass trimmer engine doesn’t pick up speed;
  • Failure of the cylinder-piston group (CPG);
  • Ignition faults;
  • There is no connection between the engine and the trimmer head;
  • Mechanical knocking during operation of the unit.
  • Repair of gasoline cylinder and piston group

The main component of any internal combustion engine is a cylinder-piston group (cylinder group), failures of which may be due to the wear of parts or low-quality fuel mixture.

The lubrication of rubbing nodes in the chain saw is done by adding a certain proportion of oil to gasoline. This process can be disrupted by old oil precipitating. In this situation, when starting the trimmer for grass, the motor overheats strongly and the most expensive breakdown occurs in a matter of minutes. To fix the problem you will need a complete replacement of the cylinder, namely: the piston, oil seals, cylinder and piston rings. If you are not a master of internal combustion engine repair and do not have experience working with technicians, it is unlikely to fix the engine without the help of a specialist. Detailed steps of grass trimmer piston repair can be found here.

When the lawn mower ignition fails, the spark on the spark plug is lost and, as a result, the fuel mixture is not ignited.

In this situation it is important not to rush with the replacement of the coil, because the cause of the failure may lie in the lack of contact in the switch on the control handle.

An important point in the search for ignition faults of the grass trimmer will be the diagnosis of the mesh, where the distance between the side and the central electrode should be 0.5-0.7 mm. In addition, it is necessary to pay attention to the sealing ring of steel on the plug, the loss of integrity or deformation of which can lead to etching of air from the combustion chamber and, consequently, a decrease in the power of the grass trimmer.

If the replacement check of the electrical circuit, the plug and its contacts did not give positive results, then it is worth paying attention to the ignition module of the grass trimmer, namely the flywheel clearance. Regardless of the design and manufacturer of the lawnmower, the distance between the ignition coil and the flywheel should be no more and no less than 0.2 mm. To restore the optimal value of the gap will need to loosen the bolts fixing the coil and a special measuring probe to expose the ignition of the grass trimmer.

A clear sign of engine power system malfunction is the absence of traces of fuel mixture on the spark plug electrodes, which can be associated with the following defects:

Parts of the Grass Trimmer Fuel System

  • a clogged hole in the gas tank creates a vacuum, which prevents the normal flow of gasoline into the carburetor;
  • due to poor fuel quality and ingress of foreign particles the fuel filter installed in the tank is clogged;
  • the mixture does not flow into the combustion chamber as a result of a clogged carburetor.

You can quickly determine the cause of malfunction by removing the fuel hose leading to the carburetor. If the fuel mixture flows out in a thin stream, you should pay attention to the carburettor. If no fuel flows, clean the breather plug (small hole in the fuel tank lid) with a fine needle or replace the fuel filter.

If the fuel is flowing into the carburetor, it is necessary to clean or adjust it. Adjusting the grass trimmer carburetor involves restoring the optimal mixing of the fuel mixture.

Grass trimmer carburetor with adjustment screws

To do this, pay attention to the three adjusting screws: maximum speed (H), minimum (L) and idle (LA). To start the setting you need to screw in the screws H and L completely and let them go 1 turn each. After starting the mower let it warm up for 10 minutes to regulate the power system in working mode. After warming up the engine, we press the throttle key to the stop (12 000 rpm). Restoring the idle speed by loosening the LA screw. As soon as the grass trimmer head began to rotate, it is necessary to turn the screw until it stops.

Repair of electric trimmer forester with his own hands

In detail: repair of electric trimmer forester with his own hands from the real master for the site

Modern technology and technology allow us to produce the best and optimal technical solutions, which become effective assistants in the arrangement of the cottage or homestead plot. Green lawns and other plantings can quickly grow, for tidying up the yard and mowing lawns, a lawn mower, otherwise known as a brushcutter or trimmer, gasoline mower is used.

Traditional lawn mowers are inconvenient and unsafe in use, require considerable time and own efforts, which will help to save lawn mowers, combining in their design functionality and practicality. In the photo you can see a variety of high-tech devices, which are characterized by a set of performance characteristics, including such parameters as increased productivity and a long service life.

Comfortable and reliable grass trimmer is a technical device, consisting of individual mechanisms, parts and elements, which can wear out, fall into disrepair and be damaged during intensive use.

Even with regular inspection, maintenance procedures and careful storage such devices and their individual parts require repair and even replacement, all repair procedures can be made by yourself.

It is easiest to give the lawnmower for repair, allocating a certain amount of money from the family budget, prompt and high-quality repair with their own hands is no less simple and convenient if you want to understand the design of the lawnmower and fix all the problems.

Mass and piece production of trimmers is based on the use of common technology, the typical design scheme consists of certain elements and parts, it is important to know them when carrying out independent repair work:

  • upper part. The base of the entire structure, where all the important elements are assembled, such as the starter, carburetor and lawnmower engine;
  • middle part. Hollow rod, inside it there is a rope that connects the engine and the gearbox, which drives the cutting line for the trimmer. In this part there are mounts to distribute the weight of the entire structure and a belt for fixing the grass trimmer on the belt of the person who uses the grass trimmer for its intended purpose;
  • lower part. The gearbox and cutting elements are located inside the brushcutter and are hidden by the practical guard to protect the user. The housing ensures an increased level of safety by preventing large particles of dirt, stones and glass from getting into the user while operating the chain saw.

Knowing precisely the internal structure and the principle of operation of the grass trimmer, you can independently carry out repair measures for the structure or replace individual, deteriorated nodes, using the instructions for repair.

The most common and common, subject to self-correcting breakdowns of the unit can be called the following problems:

  • engine malfunctions that prevent the lawnmower from starting and working properly
  • Increased vibration of the brushcutter bar, making it more difficult to use as intended;
  • Increased gearbox overheating, accelerated heating during operation;
  • slow and weak cutting line with insufficient speed;
  • clogging of the starter grid, causing the engine to overheat and stop working
  • Fast and frequent clogging of the carburetor due to the use of low-quality fuel;
  • clogging of the air filter if you do not take care of the unit.

Checking the motor

If the switch on the device and the internal wiring sections are undamaged, then you should proceed to check the electric engine. For this purpose it is necessary to remove the cover of the housing, having previously unscrewed with a screwdriver some screws.

The first thing to do after accessing the electric motor is to check the functionality of the brush unit. If the brushes are worn beyond the maximum allowable value, the electric motor can stop completely or work unstable. If the brushes and the collector are fine, you should start “testing” the motor winding. In order to rule out the possibility of a breakdown in both circuits, it is necessary to carry out alternately

Check the stator and rotor of the motor. In order to perform this operation it is necessary to:

  • Remove the motor from the brushcutter.
  • Switch on the multimeter in resistance measurement mode and check all the collector plates for breaks. When checking the motor, there must not be any significant deviations in the readings of the diagnostic unit.
  • Perform a ground fault test of the rotor winding. For this purpose connect one probe of the multimeter to the rotor “common ground” and the other to any plate on the collector. The multimeter should be set to a resistance measurement mode of more than 1 megohm. The resistance between the winding and the ground should be very high when the motor is in good condition.
  • Measure the resistance value of the stator winding. If there is no resistance, you can state in this case the fault.
  • If the stator wiring is in good order, check the possible breakdown to the housing in the same way as for the stator diagnostics.

When you use this method, you can determine the cause of motor malfunction in 90% of cases. You won’t be able to make a test for inter-twist circuits, which can occur only during the engine operation, but you can make a diagnosis in this way

by indirect signs, which are manifested in the reduction of the electric motor power and its overheating. If the motor is equipped with a thermal relay, the electric mower works for a brief period in the event of a short circuit, after which the grass trimmer switches off automatically. In some cases, the thermostat can cause malfunction of the electric motor of the grass trimmer, so the complex of checking

Checking” the thermo relay with a multimeter or a tester must be included in the set of measures.

This is very easy to do: when in good working order on a cold motor, the thermostat lets the electric current flow, in

The electrical circuit will be open in a faulty condition.

Problems with a broken wire can easily be solved by soldering the contacts, but if the motor is “burned out,” it will require a complex rewinding process, which can

Only a qualified technician can carry out this operation. In many cases, it’s much easier and cheaper to buy a new motor and install it in place of the burnt one. This work can be done independently

If the grass trimmer’s electrics are in good working order, then you should pay attention to other types of malfunctions that can occur during the operation of the electric mower.

Mechanical faults of the grass trimmer

If the electric motor of the device turns on, but the rotation of the reel with a fishing line does not occur, the causes of such malfunctions may lie in the breakage of the flexible shaft transmitting the torque. Such a problem is especially common if the electric appliance is not properly cared for. For example, if there is no lubrication inside the electric mower shaft, the cable will be subjected to excessive friction and within a short time, this part will fail. To replace the flexible shaft, simply disconnect the top part of the brushcutter and remove it from the shaft.

If you have trouble removing the second part of the cable left inside the cavity, disconnect the lower part of the grass trimmer with the reel and the shaft. Reassemble the mechanism in reverse order.

Bottom-mounted grass trimmer

Before installing, the flexible shaft should be thoroughly lubricated with grease to reduce the likelihood of repeated failure of this part.

The flexible shaft can break only on top-engine models.

Electric mowers with a bottom-mounted motor do not have a flexible shaft, but malfunctions of such devices can appear in the form of destruction of the main shaft bearing of the electric mower on which the reel with a fishing line is installed.

To fix such a malfunction is very simple enough to perform a replacement of the failed bearing with a new part.

Grass trimmer repair for grass with their own hands: frequent causes of breakdowns

trimmer for grass can fail during operation in circumstances of overloading. This situation occurs when the work area overgrown with the highest grass.

While working on such sites, the engine may fail, bearings may break, as well as ruin the coil electric mower. While working in the rain or in a very foggy environment, the grass trimmer can “burn out” and therefore the formation of a short circuit.

Breakdowns of this electronic device can also occur as a result of infrequent use. If the household device will be used in this mode, then after a certain number of hours will need to produce an unavoidable repair and preventive adjustment of many parts of the electronic device.

Start button repair

If the electric mower shows no signs of life, there may be a break in the electronic cable inside the body handle, or a faulty motor switch button.

To make an electrical diagnosis it will be necessary to disassemble the handle of the appliance. Construction is performed in this sequence:

When access to the inside of the electric mower will be provided, using a multimeter, create a measurement of the resistance of the start button of the electric trimmer. If there is no resistance after pressing this

brushes, trimmer

The part must be replaced. It is also necessary to check the connection points of the power cable with the internal electronics located in the handle

of the device. Contacts should be checked for interruption using a multimeter. Often such a fault is determined “by eye”. After detecting a broken contact, it is enough to perform soldering of the damaged place to restore the trimmer’s operation.

If you do not have a multimeter, you can do the diagnostic with an indicator screwdriver. To do this, plug the plug into the electronic mains and use this diagnostic tool

Find the “phase wire” and check the electrical current before and after the trigger. If the phase current is found in another electronic circuit, it is enough to install the electronic plug on the opposite side of the socket so that it is possible to make a correct diagnostics

Grass trimmer malfunctions. the 2nd variant of diagnostics should be created with great care, t. ะบ. there is a danger of electrocution while checking the integrity of the wiring.

the grass trimmer, REPAIR of the shaft or how to repair the shaft on the trimmer.

Even more infra about repair and a choice of the tool on pages of our site www.LookTool.come in always ready for everyone.

checking the electric motor

If the button on the device and sections of the internal wiring are undamaged, then you should proceed to check the electronic motor. To do this you need to remove the cover of the housing, previously removing a few screws with a screwdriver.

The first thing to do after accessing the electronic motor is to check the functioning of the brush assembly. If the brushes are worn above the maximum allowable value, then the electric motor can for one hundred percent brake or work unstably. If the pass, when the brushes and the collector are in order, you should proceed to “test” the winding of the motor. In order to rule out the possibility of a breakdown in both circuits, proceed one after the other

Check the stator and rotor of the motor. To perform this operation, you need to:

  • Remove the motor from the brush.
  • Switch on the multimeter in resistance measurement mode and check the collector plate for breakage. When checking also no significant deviations in the readings of the diagnostic device.
  • Perform a ground fault test of the rotor winding. For this purpose it is necessary to connect one probe of the multimeter to “weight” of a rotor, and another. to any plate of a collector. Multimeter must be set in the mode of measuring resistance more than 1 MOhm. The resistance between the winding and the mass of the motor must be very high if the motor is in good order.
  • Measure the resistance value of the stator winding. If the resistance is absent, of course to state here its fault.
  • If the stator wiring is in good order, check the stator breakdown to ground in the same way as in the stator diagnostics.

When you check using this method, in 90% of cases you will be able to determine the cause of malfunction of the electric motor. Perform a check for inter-turn fault, which can manifest itself only during the operation of the motor, this way you can not, alas diagnose such a fault is an option

by indirect signs, which appear in the reduction of the electric motor power and its overheating. If the electric motor is equipped with a thermal relay, then such an electric mower, in case of an inter-twist short circuit, will work for a period of a short time, then it will automatically shut off the grass trimmer. Sometimes, the thermostat can be a prerequisite for malfunctioning electric motor trimmer grass, because in the complex checkup

The machine has to be equipped with a thermo switch with a multimeter or a tester.

This is painfully simple to do: serviceable on a cool motor thermostat passes the electronic current in the