Trimmer Shaft Lubrication

Repair and lubrication of the trimmer reducer The device of the trimmer reducer and its possible malfunctions. How to disassemble the gearbox for lubrication? Diy lubrication and replacement algorithm.

Trimmer Gear Lubrication

Gears must be lubricated regularly in accordance with the recommendations set out in the operating instructions for the model used. This should also be done if:

• New gears were installed;
• Atypical sounds emanate from the gearbox during trimmer operation;
• Knives rotate hard.

With continuous use of the trimmer, the transmission is subject to stress from grass adhering to the blades, dirt or torque changes. The lubricant must be selected of high quality in order to extend the life of the gearbox.

Gearbox self-lubrication algorithm

No preliminary disassembly is required to lubricate the transmission. A special hole for these purposes is already embedded in the device (it is shown below). In addition to gears, when lubricating, attention should be paid to the following elements of the mechanism:

• Bearing unit;
• Flywheel and starter coil pawl.

Lubricant injection hole

Fill in oil or add solid lubricant through a grease nipple closed with a screw. In this case, actions are performed in the following sequence:

• Clean the gear case from dirt and adhered grass, especially carefully the area around the plug so that debris does not get inside the mechanism;
• Using the appropriate tool (often it comes with a trimmer), unscrew the plug;
• Into the open technological hole, the selected lubricant is introduced from a tube, or using a syringe, as shown in the graph below;
• Screw the plug into place.

Gear lubrication

If for any reason the gearbox needs to be disassembled, then the old lubricant must be completely removed from the entire surface of the gears and the housing, the shaft, and only then use a new one. It is convenient to lubricate the disassembled mechanism with solid compounds.

The entire gear lubrication process is demonstrated in the video:

It is required to lubricate the transmission unit at least once a year, but it is recommended to do this every 20 hours of intensive use of the brushcutter. If the first signs of malfunctioning with the mechanism appear, then the lubricant must be applied as soon as possible.

Repair and lubrication of the trimmer gear

With frequent, intensive use of brushcutters, the gearbox may start to warm up or make sounds that are unusual for its normal operation, for example, grinding. This indicates that the mechanism needs to be lubricated. If this is not done in time, then more serious problems will arise (for example, gears will quickly wear out and need to be replaced), up to jamming. Other breakdowns also occur with the transmission. Repair and lubrication of the gearbox can be done independently; for this, you just need to familiarize yourself with the features of these works and stock up on some of the available tools.

Used types of grease

When choosing a lubricant, you must consider the following factors:

• The degree of adhesion of the composition to the metal of the assembly;
• Product brand;
• Consumption of lubricant by the transmission mechanism.

Well-known manufacturers, for example, Stihl, Husqvarna and others, apart from trimmers, also produce lubricants for them. These products not only reduce wear, but also protect the gear metal from corrosion. Therefore, for brushcutters from these brands it is better to use their own lubricants.

Different models have different grease consumption. This is largely determined by the intensity of use of the brushcutter and the heating of the transmission mechanism. The lubricant is considered to be sufficient if the temperature of the gear unit during operation does not exceed 40C.

By consistency, trimmer lubricants can be:

• Liquid;
• Semi-liquid;
• Solid;
• Plastic.

In terms of composition, the following types of lubricants are in demand:

• Graphite, significantly reducing friction, as a result of which the rotation of the gears improves;
• Lithium, which is also an excellent anti-corrosion composition, saturated with additives that increase the wear resistance of the metal without harmful substances;
• Universal components containing highly refined mineral oils and improving performance characteristics.

Examples of suitable lubricants are: Champion EP-0, Gear Grease OREGON, Oleo-Mas, Azmol 158, Litol. 24. You should also pay attention to the advice of manufacturers on this issue and use the materials they offer. You can buy them at specialized retail outlets.

Basic gearbox malfunctions and ways to eliminate them

Various breakdowns occur with the gearbox of an electric or gasoline trimmer. The most common of them are presented in the table below. There you can also find the causes of their occurrence and methods of elimination.

Gearbox malfunction	Possible causes of failure	Remedy
the transfer unit is very hot	use of an unsuitable (low-quality) lubricant or its absence	you need to replace or add lubricant
	the gears are new and not worn	for running-in, run for a short time without heavy loads with regular stops so that the mechanism has time to cool down
jamming of the shaft during rotation, the appearance of backlash and knocking	destruction or significant wear of any of the bearings	replace the failed bearing with a new one
the transmission mechanism flies off the brushcutter bar or staggers	damage to its body	it is necessary to replace the part
		in some cases, with minor damage with a clamp made of metal, the place is pulled together with a break
not fixed to the pipe	docking point wear	you can make a winding from an insulating tape at the attachment point or change the bar
the output shaft with a knife does not rotate or stops in case of an increase in load	wear of teeth on gears or one of them	replacement of the interacting pair of worn parts is required

Bearings are destroyed due to the use of inappropriate lubricant or due to lack of it. Also, their damage is caused by the harsh operating conditions of the brushcutter and the ingress of foreign particles of material (for example, broken metal teeth of mechanical transmissions) due to the fact that the integrity of the anthers is broken.

To remove the bearing, you need to disassemble the gearbox and use a special puller. If not, then you can try to do it with a hammer with a guide. In this case, work should be done carefully so as not to damage the seat. It is not recommended to use the preheating method to shoot the bearing. This is due to the fact that the metal may lose the required performance.

Most gearbox problems can be easily fixed by hand. It is recommended to purchase replacement parts that are native, designed for the used brushcutter model.

Trimmer reducer device

A trimmer gear is a unit that transmits the rotational motion of the motor shaft to a knife or fishing line. It is located at the lower end of the brushcutter bar. The transfer assembly is also designed to reduce the trimmer engine speed.

The mechanism consists, depending on the model of the brushcutter, of several gears rotating at high speed. As a result, they heat up due to strong friction. If there is not enough lubrication, or there is none at all, then the process leads to severe overheating and failure of parts, and, accordingly, the need to carry out complex repairs. To prevent this from happening, the transmission unit should be lubricated in time. The disassembled gearbox is shown in the graph below.

Gearboxes of modern trimmers of different models from different manufacturers differ from each other in design and size of the seat. It happens:

• Round;
• In the form of an asterisk;
• Square.

Brush cutters are equipped with gearboxes with different types of gears:

• Conical;
• Worm;
• Spiroid;
• Cylindrical;
• Planetary;
• Wave;
• Combined.

The drive shaft and gearbox are heavily loaded trimmer assemblies that are subject to significant wear. Between them, the movement is transmitted due to the engagement of the teeth of the gears located at different angles to each other. The gear train works effectively only if there is no mechanical damage. In this case, the mechanism should not overheat, otherwise it may jam.

Removing and Lubricating the Upper Trimmer Shaft

First of all, we remove the lower part of the rod from the coupling, and then disconnect the coupling from the upper part of the rod (here we are talking about the coupling that connects the two halves of the rod).

Trimmer PRORAB-8406 with disconnected clutch and lower part of the bar

Now the most interesting thing: on some, like this one, holding the shaft coupling sticking out of the upper part of the rod from below with pliers, they knock it out of the rod with pliers along with the rolling bearing (here we are talking about the coupling connecting the upper and lower shafts). In some petrol cutters with a collapsible bar, like on, the coupling connecting the upper and lower shafts is pressed into the rolling bearing.

With our PRORAB-8406 trimmer and others like it, this number will not work. They do not have a rolling bearing, and the coupling (sleeve) is an extension of the upper rod shaft. A retaining ring is installed in the upper part of this shaft, which must first be removed.

The place of attachment of the upper part of the rod to the clutch housing

1. Unscrew the central screw completely. It fixes the top of the rod by partially entering the hole drilled in it. Loosen the side clamping screws and remove the rod from the clutch housing.
2. We push the shaft out of the upper part of the rod towards ourselves, as far as play allows, to get to the retaining ring and remove it. A special puller may be needed. We remove the retaining ring.

Retaining ring on the upper shaft of the brushcutter

1. Without the circlip, the upper shaft can be easily removed from the shaft from the opposite side. Lubricate it, not forgetting about the slots in the bushings (couplings) on the rod shaft and on the clutch shaft.
2. Put the oiled shaft in place in the upper part of the rod and fix it with a retaining ring. Insert the rod into the hole in the clutch cover and align the hole on the rod with the threaded hole of the fixing screw.
3. Screw in the retaining screw and secure the upper part of the trimmer bar with the side screws in the clutch cover.
4. We clean the rod connector from debris and install it from below on the upper part of the rod.

I don’t have a puller, but I use two large paper clips to remove the locking ring. First, they need to be straightened, on the one hand, make half rings for the fingers, and on the other, bend small hooks.

Hooks grab the holes in the retaining ring and try to push them apart. With difficulty, but it turns out, and the ring starts out of place. If you know another way to remove the circlip without a puller, share in the comments.

Many craftsmen recommend using grease for CV joints, this is the best option. If it is absent, lithol-24 can be used to lubricate the bar shaft of the petrol cutter, which is focused on temperatures up to 130C. But the grease, which has the worst lubricating properties and works at temperatures up to 70C, is not recommended.

However, if you urgently need to lubricate the brushcutter bar shaft, and there are no suitable materials, then solid oil or even ordinary engine oil will be better than nothing at all.

Shaft lubrication for petrol cutters, trimmers

Dismantling the petrol trimmer bar (petrol trimmer) for shaft lubrication using the example of PRORAB-8406 brushcutter. Removing the shaft from the rod is slightly different than shown in some on the internet. Consider when disassembling such devices.

Removing and lubricating the lower shaft of the petrol cutter

To remove the shaft from the lower part of the rod, first remove the coil reducer.

Lower trimmer gearbox PRORAB-8406

1. Unscrew the fully central locking screw. On the reverse side of the lower clamping screw, unscrew the nut and unscrew the screw completely in order to disconnect the coil gearbox from the protective cover.
2. Loosen the upper clamping screw and remove the lower part of the rod from the coil gearbox housing. We take out the lower shaft from the shaft from the side of the gearbox.
3. We clean the shaft from dirt and lubricate it with grease for CV joints or lithol-24, not forgetting to clean and lubricate the coupling (sleeve) with splines in the gearbox.
4. We install the shaft into the bar, and the bar into the lower gearbox of the petrol cutter and align the hole on the bar with the hole for the central screw. Screw in the central screw. Next, we wrap the lower screw, clamp the lower part of the rod in the gear case with the upper and lower screws and tighten the nut on the back of the lower screw.
5. Add 20-30 ml of grease to the coil reducer through the hole closed with the screw located on the graph on the right.

In the operating instructions for the petrol trimmer PRORAB 8405M, 8406M, it is recommended to lubricate the gearbox with grease or its analogues, in extreme cases, fill in liquid engine oil. Excess oil will leak out as the gearbox has no seals.

The user’s manual for the petrol trimmer PRORAB 8402P, 8403P, 8405P, 8406P says that it is allowed to use engine oil for two-stroke engines as a lubricant for the gearbox. There is no mention of solid oil and its analogues.

In order not to bother, lubricate the lower gear with your petrol cutters with the same grease as the boom shaft, or fill in engine oil.

Lubricant for trimmer gear. How and how to lubricate?

Occasionally, in the midst of an intense mowing operation, your trimmer will make an unpleasant grinding noise. This complains about the lack of lubrication, the gearbox is the most heavily loaded unit of the device. And soon, these warnings can be followed by a jammed drive.

What kind of lubricant should I use for the trimmer gear?

In the process of operation, the mechanical part of the trimmer is loaded by contact forces on the teeth, resistance reactions from adhering grass (sometimes with dirt), dynamic, shock loads due to constantly changing torque. Lubrication for the trimmer gearbox must fully take into account these features, so the selection of the brand must be strictly individual.

The following factors are taken into account:

1. Manufacturer’s brand. Each brand reasonably focuses on its own lubricants (you can talk about cheap Chinese products later). This applies to manufacturers such as Husqvarna, Stihl, Huter, Makita, etc. The only exceptions are trimmers of domestic production: for example, the Caliber in the user manual does not indicate the brand of lubricant at all
2. The viscosity of the lubricant. As you know, all lubricants are divided into three groups of high-viscosity (colloidal systems containing various additives), plastic compounds for universal use and solid lubricants that soften during operation.
3. Good adhesion to the surface of gearbox parts, as a result of which the grease is not squeezed out into the gaps or out of the unit.
4. The rate of grease consumption by the gearbox. Here you have to rely on your own experience and the recommendations of specialists, since some trimmer manufacturers, relying on their own service centers, do not give clear recommendations at all regarding the period of operation of the gearbox between two lubrications.

Lubricant consumption also depends on the temperature at which it retains its lubricity. When the gearbox is heated to 40C, it is considered that its operating conditions are satisfactory, and there is sufficient lubrication.

It is believed that there is no universal grease for the trimmer gearbox, but this is not entirely true. In fact, a suitable lubricant will be one that contains the following components:

• Lead-free antiwear additives;
• Solid lubricants with the presence of graphite or molybdenum disulfide (the latter is preferable, since the lubricity is fully retained for a wide range of shaft revolutions);
• Only mineral (inorganic!) Oils, highly refined.

These requirements are fully met by Gear Grease OREGON or Champion EP-0 lithium greases, domestic compositions Oleo-Mas, Litol.24, or Azmol 158, as well as those recommended by the manufacturer of a particular trimmer model.

How to lubricate the trimmer gearbox?

In the upper part of the body, where the gear block is installed, there is a technological hole, which is plugged with a screw during trimmer operation. This screw is unscrewed, and 1.52 ml of lubricant is injected into the hole using the spout on the tube. If the lubricant was purchased in a different package, then an ordinary disposable medical syringe is also suitable for this operation.

After that, the screw is installed in its original place. This procedure, regardless of the user’s recommendations, should be performed every 1015 hours of operation of the trimmer in working mode. Other reasons for updating or replacing the gearbox lubricant are the independent performance of minor routine maintenance (for example, cleaning and flushing the gears of the gearbox before the start of the summer season), repairing the unit, preserving the trimmer for the winter, etc.

If the gear unit is disassembled, it is recommended to completely remove the remnants of the old grease from the surface of the parts, even if it does not have any traces of oxidation and contamination. And only then apply new lubricant. After applying the lubricant, it is recommended to rotate the shaft several times by hand, and make sure that the lubricant is evenly distributed over all parts of the gearbox.

When lubricating, pay particular attention to the following elements:

1. Flywheel: as a rule, grass remnants stick to its surface intensively, and thickening grass juice creates additional resistance.
2. Pawl of the starter coil, which, in the process of turning on the drive, constantly contacts the grooves on the flywheel. In this case, not only mechanical wear occurs, but also mechanochemical corrosion of the flywheel-dog connection, since the materials of this pair are different (the flywheel is aluminum, and the dog is steel).
3. Bearings, if their seals are worn out, and through them, the remaining grease is squeezed out. In this case, the unit begins to vibrate intensively when loaded. This happens with Chinese-made trimmers, so in the long run it is worth thinking about replacing the bearing assembly with a better one, for example, from the Swedish company SKF.

Lower and upper gear lubrication

There are tips that recommend lubrication at the end of the season. However, most people find it best to do this at the beginning of each season. When we repair a unit, as well as carry out any disassembly, it is necessary to use lubricants. The gearbox must be additionally lubricated when the old trimmer is inserted.

Modern trimmers are equipped with a gearbox that measures the angle of transmission of mechanical energy between two components: the shaft and the head. Bevel gears are considered common, they can easily withstand high speeds, are equipped with smooth engagement, as well as an increased level of bearing capacity. The housing includes a shaft, a gear wheel, which is pressed onto the driven shaft. In order to reduce friction, bearings are installed on the bearing points of the shaft.

Petrol trimmer grease

Correctly selected brushcutter care guarantees the durability and quality of the equipment. Manufacturers try to take into account all the nuances and prescribe what materials to use for maintenance. Usually, a specific type of lubricant is not specified, it is simply given generally known standards that lubricants must comply with.

The lubricant must be selected in such a way as to take into account temperature conditions, rotational speed, load dynamics and vibration. The main requirement is that this mixture remains in the zone of maximum friction.

Based on the above information, it should be noted that manufacturers of petrol cutters are developing universal additional tools for their equipment. It can be served with general industrial compounds. The main condition is compliance with the operating conditions, namely, the presence in the composition of a substance against rust and lime, as well as a filler, which consists of a solid lubricant. Grease is poured into the gearbox through a special hole, the unit is not dismantled.

Replacement is done quickly enough.

1. First, turn off the device from the network. Devices running on gasoline must be drained of gasoline.
2. If the lubricant changes completely, then be sure to flush the gearbox. To do this, first fill in the cleaner, then rinse the gearbox well, then drain. It is important to clean the entire case.
3. Use the special tool that comes with the trimmer to unscrew the gearbox plug.
4. Apply new grease: insert a syringe with a tube into the hole and squeeze out the grease (2-5 ml).
5. We turn the shaft manually, turn on the scythe at low speed without load. This is necessary in order for the lubricant to be efficiently distributed in places subject to maximum friction.

How and how to lubricate the gas cutter gearbox?

Responsible maintenance is the key to long tool life. One of the requirements in the work of a petrol cutter is the timely lubrication of the gearbox, as well as cleaning the filters. Every user of such a unit knows what composition to lubricate the gearbox with. First, it is cleaned in several stages, then the element is removed from the casing. It is cleaned with gasoline and dried. The place for the filter is prepared thoroughly, cleaning it from dust and old oil. The main signal for lubrication of the petrol cutter gearbox is extraneous noise and rapid heating of the equipment. This means that it is necessary to lubricate the spare part as soon as possible. The lubrication frequency is specified in the instructions for the brushcutter. The experts say that gearbox maintenance should be done every 15 hours.

Prevention and possible malfunctions of the gearbox

The brushcutter requires first maintenance immediately after purchase, because the manufacturer puts in a small amount of lubricant. If the trimmer does a small amount of work, then lubricate the device at the beginning and end of the season. If the brushcutter works a lot, then we lubricate it after 30-55 hours of operation.

The main malfunctions include the most common options.

• Strong heat. This indicates that the lubrication has run out. It is necessary to add lubricants and run them in a low mode.
• Gearbox vibrates or wobbles. This situation indicates mechanical damage.
• There is a knock. Then the bearing collapsed, the boot was damaged.
• If the trimmer blade is jammed, then the mechanism should be changed completely.

How to properly lubricate the brushcutter gearbox, see below.