Gearboxes for brushcutters. how to properly lubricate them
Gearbox is the second, after the engine, one of the most important elements of the factory device economic trimmer for grass. The functionality of this mechanism directly affects the ability of the design to transmit the force from the motor to the shaft and working elements of the brushcutter. Gearbox for grass trimmer does not need frequent maintenance. all a gardener needs is to lubricate and flush it in time. Otherwise the unit will start to seize up and break down quite quickly.
Gearbox design for household grass trimmer consists of a certain number of built-in gears, which, during the operation of the mechanism, rotate at a speed set by the device. Toothed gears are designed to reduce or increase the input shaft’s original speed. Thus, when the operator presses the gas pedal, the mowing reel or the cutting blade rotates faster, and when the lever is released it rotates slower.
Gearboxes used by manufacturers of garden equipment are divided into these types:
- cylindrical;
- wave;
- worm ones;
- planetary type;
- conical;
- spiroid;
- mechanisms of the combined type.
The cylindrical reducer of a brushcutter consists of several toothed cylinders. They are quite rarely installed on trimmers for grass, as most chain saws are equipped with worm gears.
Particular attention should be paid to the planetary gears. Their built-in shafts are located in the device of the mechanism coaxially. At the same time, the shafts of bevel reducers are in a crossed position.
Another type of reducers. reduction reducers. Mechanisms of this type are not included in the standard set of brushcutter, but they are almost always used for the manufacture of homemade on the basis of garden trimmers.
Grease for the grass trimmer gearbox. features of selection?
Lubricate the gearbox regularly to keep it running smoothly without jamming or regular breakdowns. As indicated in the manual of the household trimmer for the grass, for this purpose is suitable quality grease gear oil
In some cases, well-known manufacturers of garden equipment produce their own oils, which are suitable for the lubrication of gearboxes of brand trimmers. In order to make these substances as attractive as possible to customers, they are made multifunctional. In other words, such oils are not only suitable for lubricating the gears of household trimmers, but also for the regular treatment of gears, fuel and oil hoses, as well as the maintenance of other parts and assemblies, regardless of the type and purpose of garden equipment.
As an example of multifunctional materials. Oleo-Mac brushcutter gear lubricant, which uses molybdenum bisulfate for production. Another example is Liqui Moly LM 47 MoS2. It is most often used for maintenance of CV joints, but due to its molybdenum disulfide content, it can be used to lubricate loaded high-speed bearings, including the gears of household trimmers.
An important advantage of multipurpose greases is the high level of additives contained in them. Even after complete depletion of the lubricant they continue to keep a thin and very strong lubricating film on the surface of the driving gears, which protects the parts from heat and increased wear.
Some trimmer owners use lithium-based compounds such as Lithol-24 or CTS maintenance material to lubricate gears. Because of their proper consistency, these compounds are easy to apply to the mechanism using a 5cc syringe. These substances have proven to be inexpensive and quite effective lubricants. Their only disadvantage is the need for more frequent replacement of these fluids.
How to lubricate the gearbox of a grass trimmer or lawnmower
Before the first time to lubricate the gearbox of a lawnmower, it is necessary to carry out preventive maintenance of the tool itself, and check the availability of the lubricant laid down by the manufacturer in the gearbox. During operation, the grease is applied at the beginning and at the end of the season, and during intensive operation of the mechanism. every 30-50 hours of work. Many readers and customers wonder: what to lubricate the trimmer gearbox for grass?
Our specialists give you a brief and comprehensive answer:
- the remedy should be appropriately called: “grass trimmer gear lubricant”. That is to say, grass trimmer grease is a completely different substance;
- the grease must be transmission liquid consistent, although today the manufacturers manage to fill the market with universal samples of grease that fits to all parts of the trimmer for grass. Theoretically it can not be ideal tool, because of the specific working temperatures and the friction force in each individual node of the tool, but if you can not find a special. you can try universal (carefully reading the instructions);
- if you need to lubricate the electric reducer, as, for example, on a Makita ur3501 tool, the best choice is the same-name lubricant. This also applies to other trimmers like STIHL, Champion;
- For those trimmer brands do not produce a special gear lubricant, you can use universal means, having previously read the instructions and compared with the parameters of your tool;
- We strongly recommend not using Lithium-based grease and lithium-based tool, as they are not designed for grass trimmer gear a priori.
You can understand that brushcutter, more precisely, its gearbox needs greasing, by the fact that the tool overheats and noises inside the unit. In situations where the noises are present, but also the grease on the gearbox. it must be completely replaced with a new one, but already another manufacturer. Do not disassemble and lubricate the gearbox more than once a year. A few nuances of the lubrication procedure itself:
- Do not turn our grass trimmer upside down, or gasoline will leak out.
- Remove the electrical plug (cap) from the spark plug to prevent accidental starting for safety reasons.
- Unscrew the side screw on the gearbox without losing the sealing washer by turning it counterclockwise. Use a 17 mm wrench or an Allen key.
- If there is no grease on the outer end of the screw, apply 3-4gr of it.
- By turning the gear. help the grease to spread on gears.
- The procedure should be repeated several times.
- Screw it back in, taking care of the sealing washer.
Your machine also requires brushcutter oil to be used. It is better to buy it beforehand, so that internal engine elements could work properly and won’t suffer from premature wear.
Removing and lubricating the lower shaft of the mower
To remove the shaft from the lower part of the shaft, first remove the reel gearbox.
Lower gearbox of the PRORAB-8406 grass trimmer
- Unscrew the central fixing screw completely. On the underside of the lower clamping screw unscrew the nut and unscrew it completely to separate the coil gearbox from the protective housing.
- Loosen the upper clamping screw and remove the lower part of the rod from the reel gear housing. Pull out the lower shaft from the reducer side of the boom.
- Clean shaft from dirt and grease it with grease for joints or Lithol-24, not forgetting to clean and grease coupling (bushing) with splines in reducer.
- Fit the shaft into the shaft and the shaft into the lower gearbox of the lawnmower and line up the hole on the shaft with the hole for the central screw. Screw in central screw. Next, tighten the bottom screw, clamp the lower part of the boom in the gearbox housing with the top and bottom screws and tighten the nut on the back of the bottom screw.
- let’s add 20-30 ml of grease to the coil’s gearbox through the hole covered by the screw located on the right side of the picture.
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In the instructions for use of gasoline grass trimmer PRORAB 8405M, 8406M it is recommended to lubricate the reducer with solidol or its analogues, in the extreme case pour liquid motor oil. Excess oil will leak out, since the gearbox has no seals.
In the PRORAB 8402P, 8403P, 8405P, 8406P gasoline grass trimmer user manual it is written that two-stroke engine oil may be used as a gear lubricant. There is no mention of any solideol or its analogs.
To save yourself the hassle, lubricate your mower’s bottom gearbox with the same grease as the shaft of the boom, or fill it with engine oil.
Sometimes the grass trimmer begins to grind and make unpleasant noises during intensive mowing, which indicates a lack of lubrication of the gearbox. The lower mower shaft is the most heavily loaded part, so it wears out the most. If it is not lubricated in time, the drive may soon seize!
Removing and Lubricating the Lawnmower’s Bottom Shaft
To remove the shaft from the lower part of the rod remove coil reducer first.
Lower gearbox of PRORAB-8406 grass trimmer
- Unscrew the central fixing screw. On the reverse side of the bottom clamping screw unscrew the nut and unscrew the screw completely to disconnect the reel gear from the protective cover.
- Loosen the upper clamping screw and remove the lower part of the rod from the reel gear housing. Pull out the lower shaft from the reducer side of the rod.
- clean shaft from dirt and lubricate it with grease or Lithol-24, not forgetting to clean and lubricate the coupling (bushing) with splines in the reducer.
- Install the shaft in the boom and the boom in the lower reducer of the lawnmower and align the hole on the boom with the hole for the center screw. Screw in the central screw. Next, tighten the lower screw, clamp the lower part of the rod in the gearbox housing with the upper and lower screws and tighten the nut on the reverse side of the lower screw.
- Add 20-30 ml of grease to the reel gearbox through the hole covered by the screw on the right side of the picture.
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In the operation manual for gasoline grass trimmer PRORAB 8405M, 8406M it is recommended to lubricate gear reducer with solidol or its analogues, in extreme cases it is recommended to fill it with liquid motor oil. Excess oil will leak out, since the gearbox has no seals.
In the user manual of the gasoline grass trimmer PRORAB 8402P, 8403P, 8405P, 8406P it is written that two-stroke engine oil may be used as lubricant for the gearbox. No mention of solidol or its analogues.
In order not to bother, lubricate the lower gearbox of your lawnmower with the same lubricant as the shaft of the boom, or fill it with motor oil.
Sometimes the grass trimmer begins to grind and make unpleasant noises during intensive mowing, which indicates a lack of gear lubrication. This assembly is considered the most loaded and therefore it wears out faster. If it is not lubricated in time, then soon the drive may jam!
Lubricate lawn mower, brushcutter: boom, drive shaft and other parts
The drive shaft, which is located inside the boom, transmits rotational motion from the engine to the gearbox of the grass trimmer, and the latter, in turn, to the knife or fishing line (depending on the type of cutting tackle of your machine). All of these items, including the shaft, also require lubrication to help prevent premature wear, breakage, friction, grinding, overheating, or breakage. It is mandatory to lubricate the lawn mower before its preservation for the winter, as well as as when necessary, when the parts give such a “request”. A few nuances to the procedure:
- It is not necessary to lubricate the boom, because it is the shaft itself that rotates inside the part and some of the lubricant remains on its inner walls;
- Every grasshopper needs lubrication, without exception, and the tool’s instruction manual will tell you how much to use;
- Do not forget that the grass trimmer also has an upper gearbox, which also needs to be lubricated;
- the shaft is lubricated by filling small channels at its end, because it is these that contact the gears inside the gearbox;
- Grease your brushcutter. choose the correct product from the “KosiKosa” specialty store to keep your brushcutter working and free from overheating.
Gearbox grease appears in the service catalog as a separate product. Order it at a low price and give your gearbox a long life!
The main gearbox failures and troubleshooting
Various breakdowns may occur with the gearbox of electric or gasoline grass trimmer. The most common ones are presented in the table below. There you can also find the causes and methods of elimination.
| Gearbox Failure | Possible causes of failure | Remedy |
| Transmission unit becomes excessively hot | use of unsuitable (low-quality) lubricant or lack thereof | replace or add lubricant |
| The gears are new and worn out | to run in for a short time without heavy loads with regular stops so that the mechanism has time to cool down | |
| Shaft seizing during rotation, backlash and knocking | One of the bearings is destroyed or excessively worn | Replace the defective bearing with a new one |
| Transmission unit comes off the brushcutter bar or wobbles | If the housing is damaged | the part must be replaced |
| in some cases, in the case of minor damage, tighten the place with a fracture using a clamp made of metal | ||
| it is not fixed on the pipe | wear and tear at the mating point | it is possible to rewind insulation tape on the fixing point or change the rod |
| Output shaft with blade does not turn or stops when load increases | Worn gears or one of them | The cooperating pair of worn out parts must be replaced |
Bearings are destroyed by the use of unsuitable grease or by the absence of it. Also damages are caused by the rough operating conditions of the brushcutter and the ingress of foreign material (e.g., broken metal teeth in the mechanical gears) because the integrity of the dust collectors is compromised.
To remove the bearing, the gearbox must be disassembled and a special puller must be used. If it is not available, you can try to do it with a hammer. In this case, work carefully so as not to damage the seating. It is not recommended to use preheating to remove the bearing. This is due to the fact that the metal may lose the desired performance characteristics.
If the blade stops rotating under load or stands still, it is accompanied by an abnormal sound.
Most gearbox problems can easily be repaired with your own hands. Parts you need to buy are designed for the model of brushcutter you are using.
Boom and implement drive
The rod has two very important functions: the first is that it forms a rigid framework for the entire structure, and the second is that inside the hollow metal rod there is a shaft that connects the implement with the motor. By the appearance of the rod you can determine the class of the tool, if the rod is curved. it is convenient for work, but in this case the drive is a flexible shaft, which can not transmit a lot of torque. If it is straight, there is a rigid metal rod inside that is much more solid and can transmit more torque. That’s why professional tools always have straight booms.
Lubricate gears at regular intervals as recommended in the instruction manual of the model in use. This should also be done if:
You should also regularly lubricate the trimmer’s shaft in addition to the gearbox. It is a standard of proper maintenance of the device.
Continuous use of the grass trimmer causes stress on the transmission mechanism from grass clippings, dirt or torque variations. Choose a quality lubricant to extend the service life of the gearbox.
Types of grease used
Factors to consider when selecting a lubricant:
Well-known brands like STIHL, Husqvarna and others also make lubricants for their trimmers. These products not only reduce wear and tear, but also protect the gear metal from corrosion. That’s why it’s best to use the same brands of brushcutter lubricants.
If the compound used for lubrication has good adhesion, it will hardly squeeze out of the gearbox through the gaps.
Grease consumption differs from model to model. This is determined to a large extent by the intensity of use of the brushcutter and the heating of the gearing. A lubricant is considered sufficient if the temperature of the gearbox during operation does not exceed 40°C.
By consistency grass trimmer lubricants can be:
In terms of composition, the following types of greases are in demand:
- Graphite greases, which considerably reduce friction, thereby improving rotation of the gears;
- Lithium soap, which also has excellent corrosion protection and is enriched with additives that increase metal wear resistance, without any harmful substances;
- Universal, containing mineral oils of high purity and performance-enhancing components.
Examples of suitable greases are: Champion EP-0, Gear Grease OREGON, Oleo-Mas, Azmol 158, Lithol.24. You should also pay attention to the manufacturers’ advice and use the lubricant suggested by them. You can buy them at specialized outlets.
Champion EP-0 universal grease 120 gr
Algorithm of self-lubrication of a gearbox
To perform the lubrication of the gear mechanism, it does not need to be disassembled beforehand. The device already has a special hole for this purpose (it is shown in the photo below). In addition to the gears, when carrying out lubrication, it is necessary to pay attention to such elements of the mechanism:
Use a screw to pour oil or grease into the grease fitting. Proceed as follows
- Clean dirt and grass clings from the gearbox housing, especially the area around the plug to prevent debris from getting into the mechanism;
- With the appropriate tool (often it comes with the trimmer) unscrew the plug;
- the selected lubricant is injected into the open technological hole from a tube or using a syringe, as shown in the photo below;
- screw the plug in place.
When applying the grease, you need to rotate the knife so that it is evenly distributed over the teeth of the moving gears.
If you have to dismantle the gearbox for any reason, you must remove all old lubricant from the gears and housing and the shaft before you use a new one. It is convenient to lubricate the disassembled mechanism with solid compounds.
The entire process of lubricating the gearbox is demonstrated in the video:
You should lubricate the transmission unit at least once a year, but every 20 hours of heavy use should be enough. If the first signs of malfunctions appear, you should replace the lubricant as soon as possible.
Gearbox construction
In order to better understand what lubrication is needed for your grass trimmer, it is necessary to understand the structure of the gearbox, which nodes it consists of and analyze the working conditions of these nodes.
The grass trimmer gearbox is usually located on the lower end of the drive shaft and serves two main purposes:
- to transmit the rotary motion of this shaft to the fishing line reel or to the cutter
- Increasing the brushcutter’s torque by reducing the number of revolutions
A gearbox usually consists of the housing itself, shafts, several bearings, one or more spur and bevel gears, seals (see “Technical data” on page 54) and a gearbox housing (see “Technical data” on page 58). photo).
The driveshaft rotates the drive shaft at high speed, along with the drive gear. The idler pinion has more teeth and therefore rotates slower. But the torque increases. Each shaft is supported by two bearings in the housing.
When the grass trimmer works, vibrations and shocks are transmitted to the gearbox due to changes in rotational resistance from the interaction of the cutting unit with the grass, bushes. Grass or dirt on the blades of grass also causes vibrations and oscillations with a high and constantly changing rotating speed.
In general it can be said that gearbox units operate at high rotation speed and dynamic loads. These conditions lead to high contact stress on the pinion teeth and transverse vibrations on the bearings.
Temperature regimes are average, as the tool is designed to mow grass, and this work is usually performed in summer, at positive temperatures. The friction heats up the gearbox components, but the excess heat is removed by lubrication and atmospheric air cooling of the gearbox housing.
High heat is unusual for a gearbox and indicates the need for repair or lubrication.
How to choose the right lubricant
During operation, gear units are loaded with tooth contact forces, debris drag reactions as well as dynamic and shock loads. Depending on the nature of the load, you should choose what to lubricate the grass trimmer gear.
When selecting a lubricant such factors should be taken into account:
- manufacturer’s brand;
- viscosity of the lubricant (the selection of this parameter depends on the torque of the shaft);
- adhesion to the surface of the parts of the assembly;
- intensity of grease consumption (ambient temperature, type and volume of work must be taken into account).
If a suitable lubricant is not available, a universal one can be used. The latter should contain some components:
- anti-wear additives (without toxic lead);
- high-purity mineral oils (inorganic);
- solid lubricants with graphite or molybdenum disulfide.
How to choose the right lubricant
During operation, the knots of the mechanism are loaded with contact forces on the teeth, reactions of resistance due to debris, as well as dynamic and shock loads. Depending on the nature of the load, you should choose what to lubricate the gearbox trimmer for grass.
When selecting such factors should be taken into account:
- manufacturer’s brand;
- the viscosity of the lubricant (the selection of this parameter depends on the torque of the shaft);
- adhesion to the surface of the parts of the node;
- intensity of grease consumption (ambient temperature, type and volume of work must be taken into account).
In the absence of the necessary lubricant, you can use a universal. The latter must contain some components:
- anti-wear additives (without toxic lead);
- Mineral oils of high purity (inorganic);
- solid lubricants with graphite or molybdenum disulfide.
How to lubricate the gearbox trimmer for grass
Virtually every gear reducer brushcutter is equipped with a small technological hole, which in the operation mode is plugged with a special bolt. After a thorough cleaning of the assembly from grass and debris, remove the screw and inject 1.5 to 3 ml of grease into the gearbox cavity, depending on tool brand. For easy dosing you can use a traditional medical syringe. Do not allow foreign particles and objects to get into the gearbox during the operation, because it may cause intensive wear of the gearing and its jamming.
Specialists recommend disassembling the gearbox, flushing gears and bearings at the end of the mowing season and storing the tool without operation for a long period of time, as well as re-lubricating the unit.
Properties of the trimmer grease
Special substances are used in the production of lubricants, which must meet environmental regulations and standards. After use they decompose without damaging the environment.
Material consistency initially has a high viscosity level, and during operation this parameter decreases. This factor ensures complete penetration and reliable protection of working steam in heating conditions.
Long use and trouble-free operation is ensured by timely and proper maintenance. Various materials are used for maintenance operations. Renowned manufacturers develop their own branded care products. These include: lubricant for trimmers “Husqvarna”, “Champion”, “Makita” and others. The gearbox of the gasoline grass trimmer is to be lubricated every 8-10 working hours.
Characteristics and peculiarities of trimmer grease
When servicing any hand tools where there are moving parts, a lubricant with the following characteristics and features is used:
- There must not be any solid particles in it, which can cause breakage of moving parts of the mechanism.
- The temperature at which the lubricant becomes fluid should be over 120 degrees.
- Oil should not absorb moisture and should form a strong film that protects parts from corrosion.
- Also, most importantly, the oil should be of such a viscosity that it has the ability to adhere to moving parts.
The consistency or viscosity of greases is categorized according to NLGI (National Lubricating Grease Institute), whereby in certain cases it is necessary to use oil of a certain thickness. Viscosity according to speed, the higher the speed, the more fluid the oil must be. This is the viscosity to be chosen according to the tool:
- Drills, rotary hammers, jigsaws, where gears are slow. Grease with NLGI-2 index, which is soft.
- Lightweight rotary hammers and impact drills. NLGI-1 grade, very soft consistency.
- Angle grinders, circular saws, brushcutters. Grade NLGI-0, consistency semi-liquid.
- Heavy rotary hammers, demolition hammers. Class NLGI-00, consistency very soft angle grinders, circular saws, brushcutters.
Performance
The choice of gasoline mower, or they are also called by the name of the cutting device. trimmers for grass, should be made on the amount of work, the more workable area, the more power is needed. For small plots choose household, for garden plots fit trimmers for grass middle class. farmer, for mowing large areas, especially if there are thickets of weeds or bushes, you need a powerful professional tool. a park. Such equipment has an engine power of more than 2.5 liters.с. and can work 3-4 hours a day.
Gearbox trimmer for grass includes 2 shafts. the first has a drive from the engine, and the other is used to rotate the cutting blade of brushcutter or line electric trimmer. Bevel gears are made as a unit with the shaft, but there are versions with a separate part installed on the splined joint. Models are available with different tooth angles depending on tool design. There are gearbox modifications with worm, planetary or mixed (multistage) gears.
The shafts are mounted on antifriction bearings, which are sealed with protective washers. Parts maintain lubricant retention and prevent dirt from getting into the raceways. Bearings are located in the gearbox housing, made of aluminum alloy. Split assembly, consisting of two symmetrical halves that are joined together with screws. To ensure the tightness of the joint, a separate gasket or sealant is used.
The lower gear unit of the grass trimmer is installed on the tool via a mounting socket. There are several types of joints, varying in shape.
The most common are round seating positions with diameters of 24 or 26 mm.
Available with square or multi-faceted joints. Torque transmission is made through a splined joint.
Lubricant reviews from users
Specialists advise to use only original materials, the characteristics of which meet the requirements of the manufacturer. If they are not available, you should specify than to lubricate the gearbox of the trimmer for grass. Experienced users do not advise to use solidol, because this material is not suitable for the temperature and speed characteristics of the node, as well as the consistency. Also the given material does not have antiwear properties.
The working temperature range of solidol. from minus 40 to 65 degrees, but even with these parameters in the process of heating the density of the material increases, and the grease itself becomes coarse. In case of an emergency need to treat the tool, you can use “Lithol-24”.