How to remove the gearbox from a lawnmower

Lawnmower Gearboxes: Types and Maintenance

Lawnmower, or gasoline grass trimmer. a very popular type of garden equipment. It is designed to cut grassy lawns, trim edges of property, etc. п. This article deals with the gear unit. a very important part of a brushcutter.

Gearbox of a brushcutter transmits torque from the engine to the working (cutting) parts of the device.

This function is provided by the internal structure of the gearbox, which is a system of gears that reduce or increase the speed of rotation of the parts.

Gearboxes used for homesteading are:

  • wave;
  • helical;
  • spiroids;
  • tapered;
  • planetary;
  • worm gears;
  • combined.

This classification is based on the type of traction characteristics, namely the mechanical transmission of torque.

Gearboxes also differ in shape and dimensions of the mounting hole: it can be square, round or star-shaped. Of course, the most common gearboxes are those with a circular seat. In terms of location, the gearbox can be lower or upper.

For proper operation of the mechanism it is necessary to avoid mechanical damage to gearbox parts and maintain a certain temperature regime. Any cracks, chips and overheating will cause the lawnmower/grass trimmer to malfunction and stop, which in turn will require gearbox repairs. Regular oiling of the chain lubrication system can significantly reduce the risk of such problems and increase the lifetime of your weed trimmer.


Grass trimmer gearbox includes 2 shafts. the first has a drive from the engine, and the other is used to rotate the cutting blade of the brushcutter or the electric trimmer line. Bevel gears are made as one piece with a shaft, but there are also versions with a separate spline joint. Models are available with different tooth angles depending on the tool layout. Gearbox versions with worm, planetary or mixed (multistage) gears are available.

The shafts are mounted on antifriction bearings that are sealed with protective washers. Details provide lubricant retention and prevent debris from entering the working tracks. Bearings are installed in the gearbox housing, made of aluminum alloy. The unit is split, consisting of 2 symmetrical halves joined together by screws. A separate gasket or sealant is used to make the joint airtight.

Conveyor Gear box removal

The lower gearbox for the grass trimmer is installed on the tool through the seat. There are several types of joints, differing in shape.

The most common are round seating with a diameter of 24 or 26 mm.

Honda Pro HRD536 / HRH536 Lawnmower Roller Unit Service & Gearbox Check

Available with square or polygonal joints. Torque transmission is made by a slotted connection.

Gearbox repair grass trimmer, its lubrication and replacement with your own hands

The owner of the brushcutter is likely to notice that the gearbox becomes warmer or makes a new, unusual noise during regular use that has never been heard before. These signs tell you that the mechanism requires lubrication. If you ignore them, after some time there will be new, more significant problems.

So, without lubrication, the gears wear out much faster and need to be replaced soon. In some cases the part jams during operation. It is worth understanding that a damaged transmission mechanism can cause damage to other parts of the structure.

To carry out the repair of the grass trimmer gearbox, as well as to lubricate the part is quite feasible with your own hands, if you know how to perform such procedures correctly, as well as have the right tools and materials.

Gearbox is a device for transferring rotation to the cutting part from the motor shaft. Its second purpose is to convert the angular velocity of the output shaft into lower or higher revolutions.

In the first case, the device is called “demultiplier” and is used on trimmers with powerful engines, in the second. “multiplier” and is installed on low-power tools.

The gearbox is always located at the bottom of the boom of different brands of gasoline and electric mowers, be it Champion, Huter or another brand.

The structure of the gearbox is as follows. The main parts. a shaft-pinion (for transmission of motion from the motor) and the gear wheel, mounted on the driven shaft (for rotation of the cutting unit). To reduce the friction force during movement, rolling bearings are placed on the bearing points of the shafts.

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They are protected with special washers to keep grease and prevent ingress of dirt into the seating. All parts are encased in a duralumin casing with a special grease inlet.

This is necessary so that the assembly does not have to be disassembled for relubrication.

Thus, the design of the gearbox, depending on the model and brand producing machinery (eg, Sterwins, “Proab”) includes several gears, interconnected by teeth to transmit the rotation and moving at high speed. They become very hot due to high friction.

Important! If there is no or insufficient lubrication, the gears overheat and break, making it necessary to replace the damaged elements. To avoid such unpleasant consequences, it is necessary to use lubricant in time and treat the transmission unit with it.

Features of various types of gearboxes

Manufacturers of electric and chain saws install different models of reducers on their equipment. Usually they differ in shape and size of the housing, which is made in the form of a circle (popular diameters are 24, 25.5 and 26 mm), square or star.

Another difference between Russian, Chinese and European gearboxes is the type of gears. They can be bevel, worm, spiroid, combination, wave, planetary, cylindrical. Usually worm gears are used on chain saws.

Typical faults. causes and troubleshooting

Gearboxes can be damaged during intensive use. Most failures of this unit are typical for different trimmer brands and are fixed in the same way.

  • Strong heating of the transmission unit. There are two reasons for this: the pinions are new and not lapped, or the lubricant is incorrect, of poor quality or none at all. If the problem is with the lubricant, it must be replaced. And the new gears should run in for a short time without significant loads and with breaks so that the parts have time to cool down.
  • The shaft is jammed in motion, and a grinding noise and backlash appear. These symptoms are symptomatic of bearing wear. The gearbox must be disassembled and a new part fitted. Bearing destruction is caused by poor lubrication or lack thereof, as well as increased load of the grass trimmer or the ingress of metal objects into its seating socket, which occurs due to a damaged dust cover. A special puller or a hammer with a wooden bar is required to remove and install the new bearing. Be careful not to damage the seating of the shaft. Preheating is permitted only in the most complicated cases.
  • Geareducer is loose or comes off the boom while mowing. This means that the housing is damaged and a new part must be installed. If the defects are minor, you can use a metal clamp to tighten the breaking point.
  • If the transmission gear does not stick to the shaft, the coupling is worn. You need to replace the rod with a new one or wrap some tape around the fastener if it is partially damaged.
  • The blade on the shaft doesn’t turn or stops when the load increases. One of the gears or teeth is worn out. Replace worn parts with new ones.

Most malfunctions of the grass trimmer can be repaired by the owner of the trimmer himself. You only need to have the right tools, spare parts (it is recommended to use the original ones. for your particular model of brushcutter), and know how to disassemble the gearbox to replace the damaged element with a new one.

Algorithm of lubrication of the gearbox

There is no need to disassemble the reduction unit in order to lubricate it. there is a special hole in the upper part of the housing for this purpose. In addition to gears, it is necessary to carefully lubricate such elements as bearings.

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Wear and tear of the sealed walls causes the lubricant to leave the seating and the machine vibrates. This problem is actual for Chinese trimmers. The solution is to replace the “native” bearings with high-quality parts.

Also the flywheel should be lubricated. during operation the part is covered with grass fragments that create additional resistance while mowing.

Important! It is also necessary to lubricate the starter coil latch, because when you start it touches the grooves on the flywheel. This causes wear and tear on the flywheel as well as mechanical and chemical corrosion due to the fact that parts are made of different materials (flywheel is aluminum, doggie is steel).

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Lawn mower gear lubrication every 3 to 4 days. with special lubricant for bevel gears from Husqvarna, STIHL and Oregon. Lithol is not suitable for the lubrication of trimmer gears (in the case of lawnmower repair. depending on the model). Husqvarna-545 model brush cutters proved themselves well on thinning in young growth, lightening and cleaning, during the last season of spring-summer-autumn of 2013, the volume of thinning made more than 100 hectares. During the thinning season I had to lubricate the gear of the brush cutter every week, clean the air filter and, if necessary, change the fuel filter and the spark plug and sharpen the brush cutter blade every day (2-3 times a day). Husqvarna 343 models are also well-proven but discontinued in 2012. Consumable items for Husqvarna-545 brushcutters use Oregon brand replacement parts.- Angle Gear Lubricant, Fuel Additive, spark plug, fuel filter, cord cord, saw blades and files for sharpening disc.- to match genuine Husqvarna parts and consumables and are reasonably priced for the Russian consumer. Next year, under favorable conditions on the Russian market of forestry services will additionally buy a Husqvarna-555 model more powerful brush cutters for thinning.clearing.

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Do not buy Champion grass trimmers are full of Chinese crap, trash them and suck on the Chinese. That’s the way to fuckin’ do it right.

I have a grass trimmer Champion t 541 for 10 years. Mows hay for 2 cows a year, plus (at home 1 hectare of land) weeds and weeds. I’ve seen it all. Super. Probably used to do better

And I use my trimmer to cut firewood for my plantation-it fells and shreds trees freely!

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Do not write nonsense, in 2011, bought a Champion t336 for 5200r, 32.6 cubic meters, trouble-free technology, all along I changed the only spark plug after 4 seasons to prevent, the old was working. All summer in operation, mows huge amounts of grass, mows everything, oats, potato tops. Fuel consumption is negligible, I lubricate the grass trimmer’s gearbox with lithol. Compared to the rest of China, even bigger ones, it’s just a song. Of course, the piston has already begun to settle, on the trail. Season I plan to buy a Champion more powerful, but the best technique for its price, to overpay for STIHL twice more I do not see the point

Champion T334 bought in 2009godu. Of course I only use fishing line, the knife is too vibrating. As they say, it starts up in a jiffy. After winter you fill up with gasoline and oil, flap, suck gasoline andforward. I laid a meter and a half high buryan, of course, in several times. In 2016 I found out that I have to lubricate the gearboxbecause the teeth are worn out:) New in Warm Stan. 1000rub. And it’s on again. So with my trimmer, I just got lucky.

I, too Champion t 226 line trimmer hurrah all in a row starts almost immediately 2sezon 10-12 filling already had a normal flight) assembled good quality

It is clear how to fix it, but where to buy a conical pair?

How to Disassemble Grass Trimmer Gear

In order to disassemble the grass trimmer gearbox, you need to.

  • Remove the gearbox from the pipe by loosening the two screws underneath the gearbox.
  • Wash the gearbox with a brush, for example in benzene without oil, and dry it.
  • Use needle-nose pliers to remove the ends of the locking ring.
  • Take out the second circlip in the same way.
  • Then you must strongly heat the gear housing trimmer for grass, brushcutter gearbox or gearbox lawnmower industrial (technical) hair dryer at an output air temperature of 600 ° C.
  • After that, knock out the drive shaft with the bearing and the pinion with a wooden block on top of the gearbox housing (at first, it is worth trying to knock out the bearings without heating). Hit only with a wooden bar, because with a metal, for example, a hammer can break the housing.
  • The same way we take out the drive shaft with the bearing and the pinion (strongly heat the place, where bearings sit, and with a wooden bar on the housing coaxially to the shaft, knock out a shaft with two bearings and pinion). How to disassemble the grass trimmer gearbox, lawnmower gearbox and brushcutter gearbox. To keep the heat off, you might try using a puller.

Grass trimmer reducer assembly is carried out in the order reverse to disassembly (assembly after the purchase and replacement of faulty parts). Assembling the gearbox is much easier than disassembling. everything is assembled, literally, with your fingers. Sometimes you have to tap a little, put the snap rings in, and check if the drive shaft rotates by hand.

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If you have decided to replace the grass trimmer’s gearbox with a non-original one, you should pay attention to the pipe diameter for which it is designed (often 25.4 mm or 26 mm), the drive shaft diameter (often 8 mm), the drive shaft square size (often 5 mm or 9-tooth star) and the protection fastening on the gearbox, as well as the nut (with left-hand thread, usually M10x1).25).

Block: 3/4 | Number of characters: 1838

What to do if the engine doesn’t start

In such a situation we will have to find out the reason for the malfunction. It is worth checking the fuel and air filters. You can wash the latter in gasoline or in water with detergent. It is then squeezed and dried.

Before putting it back in place, it is advisable to wet it a little (2 drops) with 2-stroke oil. If the fuel filter is broken, it will have to be replaced and it is forbidden to turn on the machine without it.

The cause can also be a broken starter in the chain saw. Some users pull the starter rope too hard, which can cause it to break. This in turn requires replacing the starter.

Main malfunctions of gasoline trimmers

Among the most frequent breakdowns are those of chain saws related to such elements of construction:

  • The engine (in particular with the piston system);
  • carburetor;
  • The fuel filter can be washed in petrol or gasoline;
  • the starter (rope breakage, spring breakage or failure to engage);
  • With the ignition system or the fuel supply;
  • The transmission mechanism (gearbox);
  • filters and muffler.
  • If the brushcutter makes unusual noises during operation;
  • The lawn mower doesn’t start, it doesn’t pick up speed or stops working
  • When the engine is running, the working part does not rotate or slips;
  • gasoline leakage;
  • Excessive heating of individual assemblies.

Smaller faults can also occur that are detected without special diagnostics:

Repairing minor malfunctions is not difficult. Repair of gasoline trimmer for grass in more complex cases will require prior diagnostics to determine the exact cause of. If you have the appropriate knowledge and skills of locksmith work, you can fix the problem yourself, replacing the failed parts.

disassembly of the electric trimmer

Electric grass trimmer consists of a main electric unit and boom. Consider how to make a disassembly to repair the electrical part:

  • Place the brushcutter on a flat surface.
  • Unscrew the fixing screws on one side of the body of the grass trimmer.
  • After removing the cover, you can perform diagnostics, repair or replacement of the electric motor, drive and bearings, brush unit, start button and other elements.
  • Assemble etletrichesky trimmer for grass should be sequentially: first install the motor, tightening the mounting screws, connect the electrical circuit, neatly stack wires in the body in the corresponding grooves, close the top cover and tighten the screws.

Disassembly of gasoline trimmer (the Gruntek BS 52X grass trimmer is shown on the video-instruction) for engine repair is performed as follows:

  • First you need to remove the gasoline engine from the boom.
  • Disconnect the starter by unscrewing the fixing bolts.
  • Remove protective cover of the tank and the tank itself.
  • Unscrew the spark plug and remove the outer cover of the motor.
  • Remove the carburetor, the nozzle, the ignition coil and the muffler from the engine.
  • In order to carry out diagnostics and replace faulty parts of the motor, first of all you need to disconnect the clutch assembly. To do this, secure the combustion chamber, and use a ring spanner to unscrew the clutch mounting bolts.
  • After repairs, reassemble the brushcutter using the same steps in reverse order.

What kind of trimmer do you use in your yard and do you repair the machine yourself??


The most important thing about gearbox maintenance is timely and regular lubrication. This procedure is necessary to reduce mechanical friction and, consequently, heat and wear of the contacting parts.

Lubricate all moving parts, especially the gears and shaft, following the directions in the instruction manual.

If for some reason you do not have access to this information, remember the important rules.