Grass trimmers are an indispensable tool in the adjoining areas, which allows you to quickly remove unwanted weeds. But, like any other technique, they break down over time. To repair or set up a garden tool, you need to know its device, the principle of operation, as well as the nature of typical malfunctions of a trimmer working both on gasoline and on electricity.
Principle of operation and trimmer device
As you know, modern grass trimmers are gasoline and electric. Representatives of these groups are distinguished by their design and operating principle, and also have some operational features.
Gas scythes are produced by brands such as Husqvarna, Huter, Champion, etc. Despite the variety of brands, the design of these devices is the same and fundamentally no different. So, an engine is placed on top of the lawn mowers, a fuel tank and a starter for starting the tool are installed next to it. There is also a switch that regulates the position of the air damper. This allows you to quickly warm up the engine at low air temperature and simplify its starting. Further from the engine comes a rod with a rigid or flexible shaft for transmitting rotation from the motor to the gearbox. The bar can be solid or collapsible, consisting of several parts.
The device of the lawn mowing rod is as follows. Firstly, there is a handle on it, which has a different shape and is adjustable for the convenience of the employee. Secondly, on the stand (and more specifically on the holder) are placed control keys connected to the drive with a special cable. Thirdly, in the lower part of the rod there is a reducer transmitting movement from the shaft to the spindle with a cutting unit. As a rule, the cutting part is a cord (reel) with fishing line or a metal knife. To protect the user, a protective cover is mounted above the mowing head with a string or a disk.
The principle of operation of the gas trimmer is as follows:
- using a starter, the worker starts the engine;
- rotation from the engine crankshaft through the shaft installed in the rod, enters the gearbox;
- movement from the gearbox goes to the spindle with a cutting unit;
- cutting tool, rotating at high speed, cuts off the shoots.
Important! To increase or decrease the spindle speed, you need to press the throttle button harder or harder.
Popular instruments of this type include the Hummingbird Partner trimmer, Patriot equipment, etc.
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Electric group trimmers. network
Electric trimmers are very easy to use and differ from the lawn mowers by the type of drive used. an electric motor is installed in them. The device of the electrohair “Stihl”, “Soyuz” or another brand has the following form. The main part is a body with an electric motor. It has power and lock buttons against accidental start-up, and a power cable with a plug. A detachable rod is attached to the body, equipped with an adjustable handle that allows you to choose the best grip for the mowing, and mount for the shoulder strap. For ease of storage and transportation, the bar is disassembled into two parts. The trimmer coil, consisting of a bobbin with fishing line, a protective casing and a knife for cutting the string to the required length, is attached to the bottom of the rack. The rotation of the bobbin from the electric motor transfers the flexible shaft.
Electric trimmers are available with top or bottom engine. In the first case, this is a technique with a power of up to 1.4 kW, which is capable of cutting tall and wet grass, as well as a thin shrub. Such devices are equipped with fishing line or metal knife. While the devices of the second type have a lightweight mechanical part, since they do not need a gearbox and shaft to transmit rotation from the engine. Their cutting unit is located on the motor spindle, which significantly increases the practicality and reliability of the design. However, such devices have a lower number of revolutions and are able to cope only with young and not very dense shoots.
To start working with the electric braid, you need to connect the tool to a power outlet and press the "Start" button on the housing. This will start the engine, and the rotation from the rotor will go to the gearbox directly or through the shaft. Upon reaching maximum speed, the tool can be used to mow grass.
Important! Unlike lawn mowing, with trimmers (especially with a lower engine) it is forbidden to work in the rain or to clean wet grass. Failure to comply with this rule may result in electric shock.
Electric group trimmers. cordless
There is another type of electric trimmer. battery. These tools are low-power and are not designed for continuous operation (on average. 15-25 minutes, when fully charged in 3-4 hours).
Advice! For battery models, it is recommended that you purchase a second battery, as the first will need to be recharged regularly.
The advantage of this type of technology is mobility and low noise level, therefore it is used in territories where it is not allowed to make noise. These are hospitals, hotels, sanatoriums. In addition, the use of these trimmers is relevant in cases where the electric cable greatly interferes with work and movement. However, before each inclusion, you need to check the battery charge.
General design features
Gasoline and electric trimmers have different designs, but in the general case the principle of operation is identical. a strongly rotating fishing line or a knife cuts grass. Therefore, the cutting side, gearbox and boom are structural elements that are the same for all types of hand mowers.
Typical malfunctions of gasoline trimmers
The design of gasoline trimmers is more complicated than electric trimmers, so they have more damage.
If there is no spark at the start of the engine, or there is a spark, but weak and insufficient to ignite the fuel, this indicates a failure in the ignition system. To eliminate it, you need to check the magneto. Sometimes it is necessary to replace the high-voltage wire, if it is broken, or to clean the contacts. Also, the cause of the spark disappearing is a damaged candle cap. In some cases, the problem occurs if the mixture fills the candle, or carbon deposits appear on it. On cheap Chinese lawn mowers, the engine sometimes does not start because the circuit breaker is broken.
Often the problem is not in the details themselves, but in the unexposed gap between the ignition coil and flywheel magnets. In this case, adjustments must be made. If this procedure is not performed, an early or late ignition of the fuel occurs.
Video: How To Replace A Fuel Filter With A Champion Trimmer
Important! As a result of non-compliance with the recommendations for adjustment, the engine runs at low power or does not work at all, the starter breaks, the cord breaks, etc.
When diagnosing the fuel system, the presence of a combustible mixture in the tank, as well as its quality, is first checked. It is prepared according to the user manual, it is forbidden to change the proportions. Also, do not make the mixture with a margin. during storage, it changes its properties and subsequently harms the equipment.
First you need replace mixture in the gas tank and restart the engine. One of the signs of poor quality fuels and lubricants. the trimmer does not switch speed and cannot gain momentum, and also stalls, regardless of how it was started. to cold or after warming up.
If the device starts up poorly again, you need to inspect the candle channel. Perhaps it got a combustible mixture. This is due to improper use of the tool: at start, the air damper is set to the off position, but after the engine is started, it is not put into the on position, which causes the engine to stall. The next time you try to start the engine, throw a candle with fuel, after which starting the device becomes impossible. To eliminate the problem, the part is twisted and thoroughly dried, since only a dry candle can be installed. You also need to drain the fuel from the candle channel, remove carbon deposits from the electrodes of the candles and when installing correctly set the gap between them.
Air filter. Another possible reason for the failure of the trimmer. If it is clogged with debris, air does not pass into the combustion chamber and the fuel does not ignite. The part is changed or thoroughly washed and dried. If oil is found in the air filter, it is washed with gasoline and dried for several hours.
Fuel filter also subject to verification. It cleans the fuel mixture from garbage. Its clogging leads to the fact that gasoline does not enter the cylinder, and the trimmer stalls. It is necessary to remove and clean the fuel filter, if necessary. change to a new one.
Breather. This is a non-return valve that allows you to equalize the pressure in the gas tank. If it is clogged, a vacuum forms in the fuel tank and no fuel enters the carburetor. You can verify this by removing the hose from the tank to the carburetor. If gas does not leak, the valve is clogged. There is a breather on the gas tank cap, sometimes on the fuel tank. The part must be disassembled and thoroughly cleaned.
This lawn mowing unit breaks due to low-quality fuel, accumulated dirt in the chamber, as well as a deformed air filter. Parts such as membranes, inlet needle, seat, strainer, adjusting lever, flaps, etc., may become clogged or broken. Diagnosis of the device and subsequent cleaning or repair are required.. In some cases, carburetor adjustment is required.
If the lawn mower stalls when the user presses the gas and increases the engine speed, this may indicate a clogged exhaust system. This is due to the large amount of burning released during the combustion of oil, which is part of the fuel mixture. To eliminate the problem, you need to clean the muffler and related parts.
Important! The only way to avoid a breakdown is to properly observe the proportions of oil and gasoline when preparing the fuel mixture.
The purpose of the starter is to assist in starting the lawn mowing engine. The main malfunctions of this node are: breakage of the cord and breakage or exit from the spring hook. To eliminate the failure, the starter is disassembled, the cord is replaced with a new one, and the spring is returned to its place, or if it is damaged, install another.
When diagnosing a piston group, the compression must first be checked. If it is not suitable, the engine will not start. Normally, it should be over 8 kg / cm 2.
On a note! On some engines there is no idle, therefore, with an indicator of 8 kg / cm 2 they stall, since the fuel mixture does not pump up. So, if the lawn mowing does not swing above the recommended value, you need to check the piston, cylinder and rings.
Another possible reason for low compression is a poorly fixed carburetor. If gasoline drips during operation, this also indicates that you need to tighten the mount of this unit.
One of the possible malfunctions of the cutting blade is the cassette cover is displaced or stuck. This is due to axis misalignment or the installation of an unsuitable mowing head. As a result of this, rotation is hindered, the load on the motor increases, and it overheats.
If the cutting blade does not rotate, the inspection of the assembly depends on the design of the rod. For a curved shape, you need to inspect the sleeve and the rod itself, and for a straight one. the shaft, gearbox and clutch. All connections between parts must be intact. The check is carried out only if the trimmer motor is working.. Sometimes confusion occurs, and users think that the problem is with the cutting unit, but the motor is actually defective.
If the cutting part of the trimmer is constantly spinning at idle of the engine, and an uncharacteristic metal rattle is heard. these are signs of a malfunctioning clutch. Typically, the cause is a bursting or extended spring. If slipping is added to this, then the pads are also faulty.
On a note! To fix the trimmer, the clutch is disassembled, inspect the spring, bearings and block. Defective items should be removed and replaced with new ones.
Drive shaft and rod
If strong vibration occurs during operation, this indicates the absence or lack of lubrication on the shaft inside the rod. In this case, even an anti-vibration system will not help. shock absorbers located between the bar and the motor. To fix the problem, it is necessary to disassemble the braid and lubricate the shaft. And in order to avoid another manifestation of such a breakdown, you need to regularly service the device. If vibration does not resolve after greasing the shaft, it must be replaced.
The gearbox on the trimmer is used to transmit rotation from the shaft to the cutting part. It includes a housing, bearings and gears. In its part, the following malfunctions can occur.
- Baskingtransmission unit. The reason is the absence or unsatisfactory quality of the lubricant. It must be added or completely replaced. Also, this phenomenon may occur when new gears are installed. In this case, you need to let the tool work under light loads, regularly interrupting work to avoid overheating of the equipment.
- Knock, play, shaft jam talk about deformation of bearings. Replacement required.
- Transmission mechanism staggers or flies off the bar. This means the case is damaged. It is necessary to replace the rod or tighten it with a metal clamp, if the damage is minimal.
- The gear does not hold on the boom. This is characteristic of a worn joint. You can change the bar or rewind the electrical tape.
- The knife does not rotate or stops under load. So. the gears are worn out (fully or partially). Replacement parts required.
Typical Trimmer Failures
Electric trimmers have far fewer knots that can break. These are parts such as the power button and electric motor.. Also, mechanical malfunctions of electric braids are not uncommon.
The first part to be checked if the tool does not turn on is the start button. The problem may be in it or a broken cable inside the device. For diagnostics, disassembly of the handle and dialing of parts with a multimeter are necessary.
If the wire and start button are intact, you need to check the electric braid motor. To do this, the case is disassembled, the brushes and the collector are inspected. If they are OK, check the stator and rotor of the motor.
If the motor starts, but the cutting unit does not rotate, the cause of the malfunction may be a breakdown of the flexible shaft. This happens in the absence of regular maintenance of the equipment. The problem is relevant for an electric braid with an engine located on top. To eliminate it, you will need to disassemble the braid and lubricate the shaft.
Important! Lubrication of the flexible shaft should be carried out regularly, otherwise it undergoes strong friction and quickly deforms.
There is no flexible shaft on trimmers with a lower motor location, but they may break the main shaft onto which the fishing line reel is mounted. The reason is bearing failure. The solution is to install a new part.
In addition to the electric motor, the thermal relay is subject to verification. This part is "called" by a tester or multimeter. Also, a malfunction may be due to open wires or poor contacts.
Summarize. To repair the trimmer, you need to know its weaknesses and characteristic malfunctions, which depend on the design features and operating conditions. Possessing this information, it is possible to identify the problem node by typical symptoms and effectively eliminate the breakdown on its own if it does not concern the engine (both gasoline and electric) or the carburetor.
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