How to Disassemble a Stihl Trimmer Reducer

Regularly using a motocosa, its owner can notice an increase in the temperature of the gearbox or the appearance of new uncharacteristic sounds in it, which had not been heard before. These symptoms indicate that the mechanism requires lubrication. If you ignore them, after a while there will be new, more significant problems. So, without lubrication, the gears wear out much faster and soon require replacement. In some cases, the part is jammed during operation. It should be understood that a damaged transmission mechanism can cause damage to other parts of the structure. Repairing the trimmer gearbox, as well as lubricating the part, is quite feasible with your own hands, if you know how to properly perform such procedures, and also have the right tool and materials.

The device and principle of operation of the trim gearbox

A gearbox is a device for transmitting rotation to the cutting part from the motor shaft. Its second purpose is to convert the angular speed of rotation of the output shaft to lower or higher revolutions. In the first case, the device is called a “multiplier” and is used on trimmers with powerful engines, in the second. The “multiplier” and is installed on low-power tools. The gearbox is always located at the bottom of the bar of gasoline and electric braids of different brands, whether it is Champion, Huter or another brand.

How to Disassemble a Stihl Trimmer Reducer

Gear unit as follows. The main parts are the pinion shaft (for transmitting movement from the motor) and a gear mounted on the driven shaft (for rotating the cutting unit). To reduce the friction force during movement, rolling bearings are placed on the bearing points of the shafts. They are protected by special washers that allow you to preserve lubrication and prevent the penetration of dirt into the seat. All parts are placed in a duralumin housing with a special technological hole for introducing lubricant. It is necessary so that you do not have to constantly disassemble the unit to perform lubrication.

Thus, depending on the model and brand that produced the equipment (for example, Sterwins, “Foreman”), the gearbox design includes several gears coupled together by teeth to transmit rotation and moving at high speed. Due to significant friction, they are very hot.

Important! In the absence or lack of lubrication, overheating of the gear occurs with their subsequent breakdown, after which it becomes necessary to replace damaged elements. To avoid such unpleasant consequences, it is necessary to use the lubricant in time and treat the transmission unit with it.

Features of different types of gearboxes

Manufacturers of electric and gas mowers install various models of gearboxes on their equipment. Usually they differ from each other in the shape and dimensions of the seat, which is made in the form of a circle (popular diameters are 24, 25.5 and 26 mm), a square or an asterisk.

Another difference between gearboxes of Russian, Chinese and European brands is the types of gears. They are conical, worm, spiroid, combined, wave, planetary, cylindrical. Typically, worm gearboxes are used on brushcutters.

Common Faults. Causes and Solutions

In intensive use, the gearbox may be damaged. Most of the malfunctions of this node are typical for different brands of trimmers and are eliminated equally.

  1. Strong heat transmission unit. There are two reasons for this: new non-ground gears or grease: inappropriate, poor quality or completely absent. If the problem is with the lubricant, replace it with another. And new gears must be run-in for a short time without significant loads and with interruptions, so that the parts have time to cool.
  2. The shaft sticks while driving there was a knock and play. Such signs indicate bearing wear. It is necessary to disassemble the gearbox and install a new part. Destruction of the bearing is caused by poor lubrication or lack thereof, as well as increased load of the trimmer or metal objects falling into its seat, due to a damaged boot. To remove and install a new bearing, you will need a special puller or hammer with a wooden block. Beat carefully so as not to spoil the landing nest. Its preliminary heating is allowed only in the most difficult cases.
  3. When mowing gearbox dangles or flies off the rod. This means. Its case is damaged, it is necessary to install a new part. If the defects are insignificant, you can tighten the fault point with a metal clamp.
  4. If gear does not rest on the bar, this means that the docking place is worn out. It is necessary to replace the rod with a new one or wind the mount with electrical tape if it is partially damaged.
  5. The knife on the shaft does not rotate or stops with increasing load. The reason is the wear of one of the gears or teeth. It is necessary to replace worn parts with new ones.

The owner of the trimmer can fix most malfunctions of the gearbox by himself. It is only necessary to have a suitable tool, spare parts (it is recommended to use the original ones for a specific model of scythe), and also know how to disassemble the gearbox in order to replace the damaged element with a new one.

Gear Lubrication Algorithm

To lubricate the gear mechanism of the gearbox, it is not necessary to disassemble the unit. For this, a special hole is provided in the upper part of the housing. In addition to gears, it is necessary to carefully lubricate elements such as the bearing assembly. The wear of its sealed walls leads to the fact that the lubricant leaves the seat and the vibration of the equipment begins. This problem is relevant for Chinese trimmers. The solution will be to replace “native” bearings with high-quality parts. The flywheel is also subject to lubrication. During operation, the part is covered with grass fragments that create additional resistance when mowing.

Important! It is also necessary to lubricate the starter coil dog, since when it starts, it touches the grooves on the flywheel. This leads to wear and tear, as well as to the appearance of mechanochemical corrosion due to the fact that the parts are made of various materials (flywheel. Aluminum, dog. Steel).

Solid grease or oil is placed in through a hole protected by a screw. In this case, perform the following actions:

  1. The gear housing is carefully cleaned from contamination, especially near the plug, to prevent debris from entering the assembly;
  2. A special device is supplied with the scythe; they remove the cork;
  3. From a tube or using a syringe, grease is introduced into the hole by gently turning the cutting unit so that the substance is evenly distributed over the gear teeth;
  4. Return to their original place the cork.

Advice! If it becomes necessary to disassemble the gearbox, remove the old grease from the housing, from the surface of the shaft and gears, and then apply a new one. When disassembled, it is very convenient to lubricate parts with solid substances.

The lubrication of the gearbox is mandatory annually, and with intensive use, this procedure should be performed every 20 hours of operation tool. If there are signs of breakage, treat with the composition of the lubrication site as soon as possible.

Lubricant selection rules

Many companies producing garden tools, such as Stihl and Husqvarna, independently produce grease for their products. In this case, it is recommended to use just such a product. It best reduces the wear of equipment. If the original grease is not available for the trimmer, several factors should be considered when choosing a composition:

  • Product quality of a brand that produces lubricants;
  • Viscosity of the composition. The shaft torque affects this parameter;
  • Adhesion to the surface of the components of the site;
  • Consumption of lubricating coating. You need to take into account the air temperature, type and amount of work performed.

Advice! If it is difficult to choose a lubricant, it is better to purchase a universal composition. It usually contains a number of additional components that protect the gearbox and extend its life.

According to the consistency, lubricants can be liquid and semi-liquid, containing various additives and additives, as well as plastic and solid. Plastic ones are the most common, and solid ones represent their original state. The most popular in composition are:

  • Graphite lubricants that reduce friction and improve the movement of gears;
  • Lithium compounds with high anti-corrosion properties and additives that reduce metal wear;
  • Universal substances containing mineral oils and additives that increase the operational properties of the gearbox.

The most common lubricants include: Litol-24, Champion EP-0, Azmol 158, as well as the composition of the production of the company “Stihl”.

Gearbox disassembly and replacement

Due to the different types of gears, the shape and size of the seat, interchangeability of gears is possible in rare cases. Therefore, when acquiring a new part, one should take into account the model of the old unit and the brand of trimmer. In the event that you still need to use a non-original device, you must choose it taking into account the following nuances:

  • Rod diameter (usually 24.5 or 26 mm);
  • Seat shape and diameter (most often. 8 mm);
  • Method of fixing protection.

If the listed parameters are the same, the old gearbox can be replaced with a suitable non-original part. And in order to carry out the replacement, you need to remove the gear from the rod and disassemble. For this, it is necessary to loosen the clamping bolts located under the structure and remove a couple of corkscrew rings using pliers, and then remove the bearings from the driven and drive shafts using a special puller. And to assemble the mechanism, you need to install the removed parts in the reverse order.

Advice! In the absence of a puller, the bearings can be carefully knocked out with a hammer and a wooden block. Impacts must be applied carefully so as not to damage the seat. However, it is impossible to crank up the attached parts, therefore, to remove them, you need to warm them up using a building hair dryer (temperature is 600 ° C).

Gearbox assembly is easier than disassembly. Parts of the structure are set in place by light hammer blows. When the device is assembled, you need to make sure that the driven shaft rotates freely if you move it by hand.

Breakdown prevention

To avoid breakdowns and subsequent costly repairs, it is recommended that you follow a series of simple rules for operating the trimmer and servicing the gearbox.

  1. Lubricate this garden tool immediately after purchase. Before starting operation. Typically, the manufacturer (for example, Interskol or Huter) applies only a small amount of lubricant, which is sufficient only for break-in.
  2. At the end of the season or before long-term storage of the trimmer, you should disassemble the gearbox, check the condition of the bearings and gear, lubricate the assembly.
  3. It is necessary to add grease after the tool has worked for twenty to forty hours. With intense loads, this time is reduced to twenty hours.
  4. Changing grease to a new one is necessary when repairing a structure or before the start of a season.
  5. When the gearbox overheats or makes a loud noise, check for grease. If it is present in sufficient quantity, it is recommended to replace it completely with another.

So, you can repair and lubricate the motokosa gearbox yourself at home. Adding lubricant will not be difficult, a detailed description of this process and recommendations for choosing the right substance can be found in the instructions for use of the tool or on the, which are many on the Internet. Most gearbox failures are typical for trimmers of different brands, it is quite easy to eliminate them if you know the correct procedure. And in order to avoid their appearance, it is enough to follow simple operating rules and conduct timely maintenance of the trimmer gearbox.