Gearbox lubrication for grass trimmers

Buying any kind of machinery is sort of a lottery, but a lot also depends on the gardener. In caring hands even Chinese models last a long time and do not let their owners down at the wrong time. And if you forget to timely lubricate the gearbox of trimmers, do not clean filters, use cheap low-quality gasoline, then the garden equipment from the most famous brands will become a headache.

Gearbox lubrication of brushcutters is one of the most important elements of gasoline grass trimmer maintenance, which must be done directly by the user.

Time and procedure for preventive maintenance of the gearbox

I recommend the obligatory preventive maintenance of a new gasoline trimmer for grass right after the purchase, with the addition of grease in the gearbox. For all the high of garden equipment, some manufacturers cut corners and lubricate the unit only to a minimum during the break-in period.

How often should the gearbox of a brushcutter be lubricated?

Often preventive inspection of the transmission with the addition of liquid grease is carried out once a year at the beginning or end of the season. If you do not use your petrol grass trimmer professionally, it is enough.

If you mow a lot, you should lubricate the gearbox of your brushcutter every 20 to 50 hours. If the operating conditions of garden equipment are hard, for example, mowing a large field at a time, and the mower has no time to cool down, or cheap lubricants are used, then the lubricant must be checked and added every 20 hours of work.

Indirect indications that the gearbox needs oiling are that the machine is overheating or noisy.

Also a complete replacement of lubricant, disassembly and flushing unit, I recommend when buying a second-hand gasoline trimmer for grass.

Gear lubricant for gasoline grass trimmer

Assortment of greases for garden equipment

According to the instructions for lubricating bevel gears, a special gear lubricant should be used. As a rule, manufacturers of garden equipment produce and recommend their brand chemicals as the most adapted to their devices.

At the same time, in order to reduce the cost of operation of garden equipment and increase the attractiveness of the brand of automotive chemicals, lubricants for garden equipment are usually made multifunctional. It is intended not only for the lubrication of gasoline trimmer gears but also for the treatment of hoses, gears and gearboxes of any garden equipment and mechanical devices operating under high loads.

This gear lubricant is sold in easy-to-use and easy-to-store tubes.

Even if the specialized gearbox grease is almost completely worn out during operation, additives still create an effective lubricating protective film on the gear surface.

It should be noted that many brushcutter owners on the expanses of the former CIS countries to lubricate the gearbox using regular Lithium-based Lithol-24 or grease for Cables. It’s easy to fill the gearbox with a 5cc medical syringe.

The undoubted advantage of using Lithium-based grease and Lithium-based grease to fill the brushcutter transmission is cheaper operation. But there are nuances that break the spears on the forums of gardeners Internet space. My thoughts on what can be lubricated with lithium-based grease and what not, read the article “Lithol as a gear lubricant for brushcutter”.

How to lubricate the gearbox of a brushcutter, petrol grass trimmer

Side bolt 17 on the gearbox of the gasoline grass trimmer

For safety reasons, in order to avoid accidental starting, all maintenance work on the brushcutter is always carried out with the electrical cap / plug removed from the spark plug. Do not turn the grass trimmer upside down to avoid gasoline leakage.

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Unscrew the side screw on the brushcutter gearbox. Depending on the cutting attachment manufacturer, there may be a hexagon socket head screw instead of the hexagon socket head screw. Screws are standard, unscrew counterclockwise. Do not lose the sealing washer.

If you can’t see any grease on the inside face of the screw, you need to add 3 to 4 grams. Spin the gear by hand, changing the direction of rotation, so that the grease is distributed to the gears.

Then put the screw back in place, tightening it firmly.

Grass trimmer gearbox design

Gearbox of the grass trimmer is a unit that transmits rotational motion of the engine shaft to the blade or line. It is located at the lower end of the brushcutter bar. The transmission unit is also designed to reduce the grass trimmer engine speed.

Depending on the brushcutter model, the gear mechanism consists of several gears that turn at high speed. This causes them to become hot due to the high friction. If there is insufficient or no lubrication, the process leads to severe overheating and failure of the parts, and, accordingly, the need for complex repairs. To prevent this from happening, it is necessary to lubricate the transmission unit in time. The disassembled gearbox is shown in the photo below.

Gearboxes of modern trimmers of different models from different manufacturers differ from each other by design and the size of the seating. It comes in the form of:

The most common round seat diameters are 24, 25.5, and 26 mm.

Mowers are equipped with gearboxes with different types of gears:

  • bevel;
  • worm gears;
  • Spiroids;
  • cylindrical;
  • planetary;
  • Wave;
  • Combination.

The drive shaft and gearbox are heavily stressed parts of the grass trimmer that are highly susceptible to wear and tear. Between the two, movement is transmitted by the binding of the gear teeth at different angles to one another. Toothed gears only work effectively if there is no mechanical damage. Must not overheat, otherwise it could seize.

Types of gears on the grass trimmer

It is worth noting that the basic components of cylindrical mechanisms are gear cylinders. Most trimmers are equipped with worm gears, but much depends on the manufacturer’s decision and other features.

A feature of the planetary type of gears is the coaxial arrangement of the shafts, while bevel objects have an intersecting arrangement. Toothed transmission is relevant only for those units that are used in certain temperature conditions. over, any mechanical damage can be fatal.

Gearbox Lubrication Process

A gearbox is a mechanical device that is designed to transmit torque from the motor to the cutting equipment. Located at the bottom of the grass trimmer.

Immediately before preventive maintenance, remove the electrical cap (or plug from the plug). Do not turn the grass trimmer upside down to avoid fuel leakage. To replace the grease, you should disassemble the device.

The disassembly process consists of the following steps:

  • Unscrew the side screw.
  • If there is no trace of lubricant, it must be added (3-4 grams).
  • Then the gear is cranked by hand. This is done to distribute the material evenly over the gears.

The operation should be repeated several times. The assembly must be tightly filled with grease. At the end of the operation, the screw is set in place and tightened tightly.

To lubricate the grass trimmer gearbox, clean the plug and the area around it of dirt, and then unscrew it. Lay the lawnmower on its left side. By turning the gearing, grease is simultaneously added to the gearbox housing until it is full.

grease, lubricate, gearbox, grass

Grease choice

During grass mowing, the mechanical component of the grass trimmer is subject to shock loads due to constantly changing torque, contact forces on the tines, dynamic loads, and resistance reactions from dirt and grass clippings. A new grass trimmer gear lubricant must take all of the above points into account, and therefore, in each case, the choice of composition is made individually.

  • Intensity of grease consumption by the gearbox. Many trimmer manufacturers, relying on their service centers, do not indicate any information about the period between lubrications. Therefore, the choice often has to be made on the basis of expert recommendations and your own experience.
  • Grease viscosity. Today’s lubricants are made up of three different types: solid lubricants that soften during operation, plastic compounds for universal use and high-viscosity mixtures with various kinds of additives.
  • Make of manufacturer. Each manufacturer, whether Makita, Husqvarna, Huter or STIHL, necessarily focuses on the compositions of its own production. Domestic grass trimmers are an exception, but their manuals don’t say a word about the type of grease to work with.
  • Compound adhesion to the gearbox surface. It is important that the lubricant is not pressed out of the unit or into gaps during operation.
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Lubricant consumption is also influenced by the temperature at which the grease retains its lubricating power. Thus, a gearbox surface heated to 40 degrees is considered optimal for grease, the amount of which is considered sufficient.

There is an opinion that gearbox lubricant cannot be universal, but this is not quite right. In fact, the optimal lubricant is considered the one that contains at the same time:

  • Inorganic mineral oils with good cleaning properties;
  • Solid lubricants with molybdenum disulfide or granite. And the first option is more preferable, because with it the lubricity remains as long as possible with a large number of revolutions of the shaft;
  • Antiwear additives without toxic lead.

The listed requirements can boast greases recommended by the manufacturer of a specific model of trimmer for grass, domestic compositions Azmol 158, Litop-24 and Oleo-Mas, as well as lithium compositions Champion EP-0 and GearGrease OREGON.

Troubleshooting and solutions

If you want to apply new lubricant to the working mechanism of your brushcutter, switch the machine off beforehand. The spark plug of the grass trimmer must be disconnected from the top cap or plug. The lawnmower itself must be placed in its natural position, it must not be upside down, as this can cause the fuel mixture to leak.

Gear lubricant for grass trimmer is applied in the following order:

  • The operator must first unscrew the screw located at the side of the integral gearbox. Some manufacturers complete their brushcutters with hexagonal screws, others. with screws with a key 17. Both in the first and in the second case, the thread on the fasteners is usual. The key must be turned against the clock hand to remove the locks. At the same time you need to be very careful and careful not to lose the sealing rubber washer;
  • Then check the inside face of the bolt. If no traces of oil can be seen on its surface, it means that about 3-4 grams of grease should be introduced into the regular gearbox. In order to spread the substance evenly over the gears and other parts, you need to slowly rotate the gear by hand. This action should be repeated several times;
  • Then you need to add about the same amount of grease and spin the gear a few more times. As a result, the grass trimmer gearbox will be completely filled with lubricant.

You then have to screw in the screw and “run” the oil in the gearbox. Start your trimmer, gently press the gas pedal lever, and wait 2-3 seconds for the grass trimmer to lubricate. Mowing head should rotate at slow speed to spread oil around the gearbox without risk of overheating the moving parts of the mechanism.

Varieties of lubricating compositions

Greases of different consistencies are used for caring for the nodes of the mechanism:

  • Semi-liquid. These formulations contain a variety of additives and chemicals.
  • Plastic. Are the most universal variant. Most often used for gear and screw drives.
  • Solid. Platelet suspensions in the original state.

Special gearbox compound is a semi-fluid system.

Popular is the STIHL grass trimmer lubricant. Thanks to the special composition and components, wear and corrosion resistance are considerably reduced. The key properties of this brand of grease are

STIHL lubricant is suitable for brushcutters and trimmers and all transmissions with enclosed housings.

Signs of frequent malfunctions

Knowing the inner workings of the lawnmower and how it works, you can easily troubleshoot with your own hands. Some breakdowns occur most often and they are highlighted as the main.

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If the lawnmower does not run or even starts, look for engine malfunctions

It is also worth paying attention to this part of the lawnmower if unusual noises or strong vibrations are heard during operation. Engine problems can also be caused by a clogged air filter

If the fuel does not flow into the combustion chamber, the fuel filter is blocked. It is also worth looking at it, if the tool does not work at low speed.

No spark. This is not uncommon if the fuel floods the spark plug.

The brushcutter boom vibrates a lot, making it difficult to operate.

Gearbox gets excessively hot in a short time, which can be felt during the operation of the grasshopper.

At low speeds, the trimmer line spins weakly, which affects performance.

Starter grill is clogged. the cause of engine overheating and shutdown. The starter can also fail when the cord rips when starting too sharply.

Clogged carburetor can be caused by low-quality fuel

It is also important to pay attention to the carburetor in time if the mixture leaks

The lawnmower stops after shutting down if the carburetor is not properly set.

Malfunction. Blade does not turn, spool does not turn.

The transmission of these chain saws consists of a lower gearbox, a shaft and an upper gearbox (cup). Let’s take a closer look at them.

The gearbox consists of a housing and gear pair, which are subject to wear.

This is caused by lack of lubrication in the gearbox.

Do not neglect this procedure when using the lawnmower.

Lubrication control will prolong the life of the gearbox.

On sale there are sets of gears for these reducers, but their cost exceeds 60-70% of the cost of the reducer, moreover, the process of replacing them is time consuming, a simple solution would be. to replace the reducer for a new.

Traction is transmitted from the engine to the gearbox by a rigid shaft that has splines on the end. Splines can wear out due to lack of lubrication in the gearbox. This situation can only be solved by replacing the shaft with a new one

Please note that there are 3 types of shafts (7 splines, 9 splines and “square”). The length of the shaft, as a rule, on these models is 152mm

Replacement is very simple. remove the old shaft. install the new.

There is a clutch cup in the upper gearbox that has splines for the shaft.

If these are worn, it will be necessary to replace it.

Cup can be replaced separately or the entire upper gearbox can be replaced.

To remove the cup, you must remove the retaining ring (p.49), catching its “ears” in the holes of the cups (n.48).

Note that there are also shaft options on the cup (7 splines, 9 splines and “square”)

grease, lubricate, gearbox, grass

Is the blade or spool rotating at idle (assuming “correct carburetor settings”)

If this malfunctions, the clutch spring will need to be replaced, or the clutch assembly will need to be replaced.

To change the clutch, it is necessary to unscrew the top gearbox of the transmission. Next unscrew the spark plug and secure the piston movement with the special stopper. Unscrew the 2 clutch mounting screws (n.57) with washers (nr.56), remove the clutch assembly and washers underneath (n.53). Replace the spring on the clutch or install a new one. Don’t forget to put washers (n.53) then the clutch, and tighten the bolts (n.57) with special washers (par.56).

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