Chainsaw Friendship 4 - carburetor adjustment and chainsaw repair

Model range overview

All Druzhba chainsaws produced were equipped with an air-cooled MP-1 engine; the air was supplied by a flywheel on which the blades were made. For power supply, a carburetor with a diaphragm was used, which ensured the supply of the mixture regardless of the position of the tool. The high power and weight of the equipment limited the scope of use of the tools that were supplied to logging enterprises. To operate the power unit, a mixture of gasoline and oil for two-stroke engines was used (which was replaced by the M8 engine).

Friendship 2

An early example of a saw, equipped with a 3 hp motor. The handles, made of steel pipe, are bolted to the engine flywheel housing. The design does not provide damping pads at the motor mounting points or a chain brake. The tool is lubricated manually; a centralized fluid supply is not installed. The production of the tool continued for several years, after which chainsaws with an improved design came to replace it.

Friendship 4

The handle is secured to a separate cast clamp placed on the engine crankcase. The MP-1 engine capacity remained the same (94 cm³), but modifications to the gas distribution diagram and installation of a modernized carburetor increased the power to 4 hp. The permissible number of revolutions has also increased (up to 5200 per minute), while the weight of the tool has remained unchanged (12.5 kg). The chain lubrication system was not installed at the factory; the owners subsequently modified the tool themselves.

Friendship 4-A

The shortcomings identified during the industrial operation of early models of Druzhba saws led to the creation of another modification, 4-A. A system for supplying oil to the blade (by gravity) was introduced into the design, and reinforced bearing supports for the crankshaft began to be used. The chainsaw now has an emergency brake that is activated when the chain breaks. The engine was equipped with an improved KMP-100 carburetor and a modernized magneto. The power and other technical characteristics of the saw remained unchanged.

Friendship-4A-Electron

To improve performance characteristics, a transistor ignition unit was installed on the saw, which ensured stable sparking. The engine began to start at low air temperatures without preheating. The rest of the instrument has not undergone any changes.

Friendship 4M Electron

The Druzhba M modification received an automatic lubrication unit for the working chain. The damping elements were modified, and rubber linings with increased wall thickness began to be used on the handles. To prepare the working mixture, a KMP-100U membrane carburetor is used; fuel fluid is supplied by gravity. gbks weight is 12.5 kg; For felling trees, a 450 mm long tire is used.

Friendship-5E

The chainsaw is distinguished by the use of an engine with increased power to 5 horsepower. The design uses a conical main pair, which makes it possible to transmit increased torque and at the same time reduces the weight of the equipment to 11.7 kg. The attachment points of the power unit to the frame are equipped with rubber bushings, which reduce the level of vibration during operation. An automatic chain lubrication system has been introduced using a pump that supplies fluid from a separate tank.

Druzhba-Altai

The saw is a 4M unit assembled at the production site (Altai). The equipment was equipped with a modernized KMP-100U carburetor and a contactless ignition system. A pump is used to supply fuel. The equipment has no external differences, except for the use of a protective casing for the air filter. The chainsaw has improved starting characteristics. Production of products ceased in the second half of the 90s.

Friendship 60

The saw is equipped with a two-stroke single-cylinder engine with a power of 3 hp. with a working volume of 94 cm³. A cable starter with forced return of the cord to the reel is used, the speed control is located on the right handle. A gearbox with a gear ratio of 0.319 is used to drive the chain. Torque from the crankshaft is transmitted to the gears by an automatic centrifugal clutch, which requires adjustment during operation.

Engine

In most cases, the following problems occur in engine operation:

• the engine stopped starting;
• the engine starts, but after a while it stalls;
• the engine is not able to develop the required power;
• The engine is extremely unstable.

How to check crankshaft seals

The presence of oil seal leaks can only be checked by getting to the crankshaft itself and carefully examining it for leaks. You can see how to do this correctly in the video:

How to check compression on a chainsaw

At a compression level below 8 atmospheres, the engine will not have enough power, which means the chainsaw will not be able to fully function.

To measure compression you need:

1. Remove the protective cover and unscrew the spark plug.
2. Insert the tip of the compression gauge into the hole where the spark plug should be located.
3. Using the starting cord, rotate the piston and remember the maximum readings of the measuring device.

How to properly install a piston on a chainsaw

The work of replacing the piston for most models of modern chainsaws is carried out according to the following algorithm:

1. The top and side covers are removed.
2. The candle is unscrewed.
3. The stoppers are removed from the shock absorbers and the handle is disconnected from the body.
4. The drive sprocket and starter are removed.
5. A piston stopper is installed in the spark plug hole and the nut securing the flywheel and clutch is unscrewed.
6. The flywheel, clutch, and worm drive of the oil pump, located immediately behind the clutch mechanism, are removed.
7. The screws securing the carburetor and air filter are unscrewed, after which these components are removed along with the engine control lever.
8. The ignition coil is removed, as well as the muffler.
9. The saw is turned upside down and, by unscrewing the screws securing it to the body, the engine is disconnected.
10. The pan is unscrewed and the piston is removed.
11. Since the piston is removed only together with the crankshaft, to disconnect it it is necessary to remove the retaining rings.
12. The old piston is replaced with a new one, but as carefully as possible. This is caused by the high fragility of compression rings.
13. The crankcase is put in place, and sealant is used instead of a gasket.

All subsequent actions are carried out according to the reverse algorithm of disassembly.

Model range of chainsaws Druzhba

The advantages of the Druzhba chainsaw, in addition to those mentioned above, are that it cuts smoothly and accurately, is highly productive and all the parts are in a durable case. Its disadvantages include significant weight - more than 12 kg with dimensions of 86.546x50 cm and a cable starter.

The main difference between modifications of the Friendship chainsaw is engine power:

• Friendship 2 has a power of 2 kilowatts, manual start and, unlike the 1st model, an element for chain braking.
• Druzhba 4, which received “gold” at the World Technology Exhibition in Brussels in 1958, has almost one kilowatt more power, sawing effortlessly, with shaft revolutions of more than five thousand, a half-meter log in one minute.
• Friendship 4M-electron, having a contactless electronic ignition system, uses the engine resource more efficiently, with almost the same power - 3 kW. The cylinder's chrome coating adds wear resistance, and rubber gaskets reduce overall vibration. In modification 4A, an oil pump is installed for forced lubrication of the chain.

Like any other technical device, the Druzhba 4 chainsaw requires constant carburetor adjustment, attention, regular care and preventive maintenance. At least once a year it is necessary to fine-tune the Druzhba 4 carburetor, including its adjustment.

How to properly break in a chainsaw - the main threats

What, in fact, is the problem with many councils. Let's figure it out in order.

There are other options for advice. It’s impossible to list everything.

Advantages and disadvantages

Advantages of petrol saws of the Druzhba series:

• the use of aluminum alloy for the manufacture of the body;
• removable structural elements fixed with threaded connections;
• high power and increased engine torque;
• when the chain jams, the motor does not stop;
• the use of gasoline with an octane rating of less than 80 is allowed;
• the design of the handles allows you to saw wood while standing;
• high build quality (especially products of early modifications);
• chrome plating of the working surface of the cylinder is provided.

Equipment disadvantages:

1. there is no emergency stop button for the engine; when the speed drops, the shaft is disconnected from the chain gear by a centrifugal clutch;
2. the heavy weight of the saw, making it difficult to carry the product;
3. spontaneous loosening of threaded connections;
4. high noise level during operation and oil emission from the exhaust pipe;
5. the use of an internal combustion engine imposes restrictions on the use of the tool indoors.

Most common faults

1. The engine does not start. Check for a spark at the spark plug electrodes. Make sure there is no damage to the wire insulation, clean or replace the spark plug if necessary.
2. Make sure the fuel tank is tight; interruptions in engine operation are often caused by moisture and condensate getting into the fuel mixture.
3. Adjust the carburetor
4. The most common cause of overheating is a lack of lubrication. Correct the problem.
5. Check the serviceability of the muffler. Its design is quite simple; repairs are possible at home.
6. The reason may be a malfunction of the ignition module, as well as a violation of the gap between it and the magnetic circuit in the flywheel. Gap length – from 0.2 mm. up to 0.5 mm.. This value is set using a special gasket, which is located between the flywheel boss and the ignition module. The broken module is replaced. In addition, you can replace the spark plug.

Carburetor adjustment and muffler cleaning

If excess fuel is eliminated, but the breakdown is not corrected, then the carburetor may not be adjusted.
To fix this, follow these steps in strict order:

• turn the fuel screw until it stops;

• unscrew it three turns. No more, no less;

• screw the propeller firmly;

• unscrew it already two strict turns;

• Seal with sealant or wrap thin sheet metal around the adapter coupling.

Everything that must be firmly and tightly connected. The quality of the chainsaw depends on this.

There are times when the chainsaw motor only works at low speeds and stalls at high loads. A similar problem may indicate a clogged muffler.

The muffler spark arrester can become clogged for several reasons:

1. Using low-quality oil;
2. The fuel mixture has a high oil level;
3. Using oil not intended for such engines.

In any of these cases, you need to remove the muffler and clean it well with various detergents. After that, dry it with a hairdryer.

Read here how to choose the right chainsaw.

The Druzhba chainsaw is a mechanized tool that is used to cut thick branches, clearing power line routes, as well as felling trees. Whether a given instrument is of the highest quality or not is difficult to answer. Some consider him a reliable assistant, while others do not like him, as he is clumsy and capricious. Nowadays, this chainsaw model is popular not only in Russian markets, but also outside the Russian Federation. This unit is available in almost every family living in villages and villages. Therefore, whether it is reliable or inconvenient is impossible to answer. But like any other tool, this chainsaw tends to break. Is it possible to repair a Druzhba chainsaw yourself at home? If you wish, you can. But, if it is carried out in specialized workshops, then this repair will result in a good amount.

What can be done to extend the life of a chainsaw without repairs?

Repair of the crankshaft main bearing has to be carried out quite often, since this is the most vulnerable point of this model of chainsaw. As soon as it becomes faulty, the ignition begins to go astray, which leads to unpredictable operation of the tool. With such a breakdown, in some cases it is almost impossible to start the chainsaw. But in other cases it simply cannot be drowned out in any way. This model was recently equipped with a button that forcibly stops the operation of the unit. Craftsmen who are well versed in this have installed such buttons on their units themselves much earlier. Chainsaw Friendship is a capricious tool. Under intense load, it has a considerable list of failures, including broken connecting rod, jamming of the piston, as well as loss of spark and gearbox malfunction.

The presence of contact ignition in a chainsaw also causes a lot of trouble, since it is sensitive to various brands of not only oil, but also gasoline. Therefore, to prevent this problem from leading to tool repair, experts strongly recommend replacing the contact ignition with an electronic one. This model of chainsaw should be constantly adjusted and tuned. If problems with the carburetor are quite common, then you can solve it by bending the gasoline valve inside. As a result, the amount of fuel that enters the engine is limited.

User manual

When working with the Friendship saw, you must follow the operating rules:

• Start-up and operation is prohibited with a damaged or removed air filter;
• the instrument is held with two hands;
• To protect the operator, special clothing and glasses are used;
• at the moment of starting, the saw chain should not touch the ground, stones or other objects;
• It is not allowed to saw wood without filling the tank with oil;
• It is strictly forbidden to refuel the saw with pure gasoline;
• when operating the saw for a long time, it is necessary to take breaks to cool the motor (every 40-45 minutes);
• The tightness of threaded connections is periodically checked;
• If parts of the saw are damaged, operation of the tool is suspended.

Before using the saw, you should read the instructions from the manufacturer. To make a fuel mixture, you need to prepare gasoline and special oil. Half the volume of prepared gasoline is poured into a clean container, then lubricating fluid is added and mixed thoroughly. Then the remaining gasoline is poured into the mixture, the solution is further mixed and filled into the tank. When running in the engine (after replacing the rings), it is recommended to introduce additional oil to ensure the running-in of the rubbing surfaces.

When felling wood, a cut is first made, located on the side where the trunk should fall. Then the trunk is sawed on the other side; There should be no unauthorized persons within a radius of 50 m from the tree being cut down. The operator moves from trunk to trunk with the saw running at idle speed (without chain rotation) or with the engine off. The operating instructions do not allow sawing of trunks tied into logs or stacked.

During operation, it is necessary to adjust the engine idle speed and adjust the carburetor to achieve maximum power. The equipment requires adjustment of the clutch, which overheats during prolonged operation and loses its original characteristics. Since the saw chain stretches during operation, it is necessary to adjust the tension of the element. A correctly tensioned chain moves along the bar by hand and has no sagging in the lower branch.

Operation, maintenance and repair

To ensure trouble-free operation of the saw, it must be adjusted periodically. The operating instructions supplied with the equipment describe the features of setting up the model. Incorrect configuration will lead to unbalanced operation of the nodes.

How to adjust the carburetor

Failures occur when not enough or too much fuel is supplied, as well as if the proportions when mixing fuel with air are violated.

Carburetor adjustment is carried out as follows:

1. The fuel regulating screw is first turned all the way, and then back (counterclockwise) 1.5-2 turns.
2. Start the engine, warm it up for 1-2 minutes and turn the T screw in one direction or another to ensure its stable operation at maximum speed. The chain should not move along the bar at idle speed.
3. Check and, if necessary, seal the connection between the carburetor and the cylinder.

It is easier to adjust the carburetor using a tachometer, but at home, in most cases, engine operation is adjusted by ear. When both the quantitative and qualitative fuel supply is normal, the engine does not overheat, does not choke, runs smoothly, without sharp sounds. When adjusting, turn the screws slowly, without jerking.

How to set the ignition

Stable operation of the engine is ensured by correctly adjusted ignition - the Druzhba 4 chainsaw in this case will consume a minimum amount of fuel. The saw is ignited thanks to a magneto using a spark plug and a special wire.

To monitor the quality of the spark for igniting the chainsaw, place the spark plug on the cylinder body and pull the starter. If the spark plug is in working condition, a spark will jump between the electrodes. A weak spark will not ignite the fuel; such a spark plug must be replaced.

It is better to replace the contact ignition of a chainsaw with an electronic one. This will eliminate constant problems with its regulation. It is necessary to ensure that the ignition coil mounting screws do not loosen.

Basic malfunctions and their elimination

If you know why the tool malfunctions, you can repair it yourself at home.

When the Druzhba 4 chainsaw engine starts and stalls, the reasons may be as follows:

1. There is not enough fuel in the gas tank. It is necessary to add the mixture according to the instructions supplied with the instrument.
2. The spark plug was splashed with fuel. This prevents a spark from forming. The candle must be removed, dried, and heated on a gas burner.
3. Poor contact between spark plugs and wire. This occurs due to the increased gap (more than 0.5 mm) between the tip of the spark plug and the wire. The spark plugs must be cleaned of carbon deposits with a wire brush and blown with air. They need to be changed periodically.

If engine malfunctions occur at idle, repairing the Druzhba 4 chainsaw comes down to the following:

• replacing the fuel mixture with reducing the amount of oil;
• cleaning the air filter and muffler (due to its clogging, the engine runs but does not develop speed);
• checking the fuel line and replacing the tube if necessary.

If the cutting speed has decreased and the tire is “driving”, pay attention to the sharpness of the saw teeth. A well-sharpened chain is more important than a strong engine. It is best to take it to a master for sharpening or use a machine with a rotary sharpening disk

The bevel of the Friendship saw blade on the bottom edge is 45°, and on the side edge - 60°. The height of the limiting protrusions relative to the chain teeth must be the same and checked after 3-4 sharpenings of the chain

It is best to take it to a specialist for sharpening or use a machine with a rotary sharpening disk. The bevel of the Friendship saw blade on the bottom edge is 45°, and on the side edge - 60°. The height of the limiting protrusions relative to the chain teeth should be the same and checked after 3-4 sharpenings of the chain.

The reasons why the Friendship saw does not start may be the following:

1. The fuel mixture does not comply with the repair and operating instructions for the model.
2. Manufacturing defects. Repairs are carried out in a warranty workshop.

When assembling, even if the parts fit tightly, you should not use force, for example, hitting them with a hammer. By replacing worn elements, you can restore the functionality of the chainsaw or extend its life.

Technical characteristics of the Druzhba chainsaw

The Druzhba 4 chainsaw has excellent technical characteristics, which makes it stand out among modern professional models. Among the design parameters of the Soviet instrument, the following should be highlighted:

• Engine power – 3.5 l. s./2600 Watt;
• The recommended tire size for work is 45 cm;
• Saw chain pitch – 0.325 “;
• Reservoir for filling fuel – 550 ml;
• Lubricant tank – 260 ml;
• Weight – 7 kg.

Representatives of the 4th generation of Druzhba chainsaws have the highest technical characteristics among the entire line of chainsaws of this brand. By the way, their predecessor, the Druzhba 2 chainsaw, has a power of 2.8 liters. pp., which significantly reduces the ability of the instrument in practical use.

What other carburetors were installed on the Ural 2t Electron chainsaw?

The Ural 2t Electron chainsaw was often equipped, and is installed today, with carburetors from other two-stroke engines with the following engine parameters:

• power 5.5 hp
• combustion chamber volume 90.4 cc,
• piston diameter 55 mm.

Sometimes carburetors from much more powerful engines were installed. For example, from motorcycles “Minsk”, “Voskhod”. True, there is a drawback: the supply of the fuel-air mixture increases significantly. It was reduced by adjusting the screws. The engine worked, but the excessive fuel consumption was significant.

Walbro carburetor for Ural chainsaw

On the Ural 2t Electron chainsaw, the German carburetor from the Stihl MS 660 chainsaw, which is similar in power, has proven itself well. Its fuel mixture supply almost completely corresponds to the Ural 2t Electron engine. A perfect fit is achieved by adjusting the screws. Also, the mounting dimensions are almost identical (between the holes on the carburetor and the studs on the engine). A difference of 1 mm is eliminated by sharpening both holes with a file, each by 0.5 mm.

This is what a Walbro carburetor looks like, which is installed on a Ural chainsaw

Basic malfunctions and ways to eliminate them

The main malfunctions encountered when operating the Druzhba saw:

1. Difficulties starting the engine occur when the level of gasoline in the tank is insufficient or the pipeline is clogged. The defect is observed when the mixture is excessively enriched. To restore performance, it is necessary to blow out the engine by cranking it with a manual starter. If the saw has been stored for several months with a full tank, then the quality of the fuel decreases due to the evaporation of volatile fractions of gasoline.
2. The engine does not start due to incorrect ignition adjustment. It is necessary to set the gaps in the contact group in accordance with the instructions. Additionally, the distances between the spark plug contacts are checked.
3. Insufficient engine power indicates wear of the piston group or the presence of gaps in the connection between the cylinder and the crankcase. The problem occurs when the jets are clogged, which need to be flushed and the carburetor adjusted.
4. Heating of the gearbox housing during operation of the saw indicates a decrease in the lubrication level. To repair a Druzhba chainsaw, you need to introduce a lubricant like Litol-24 or Konstalin-1 into the crankcase of the mechanism.
5. Clogging of the air nozzle and jets leads to interruptions in the supply of the fuel mixture and failures in engine operation. To restore functionality, you need to remove the device and wash the parts in clean gasoline. Check the mobility of the throttle valve - if the element is stuck, the air flow does not reach high speeds and does not ensure fuel intake through the jets.
6. Violation of the cut geometry indicates improper sharpening or deformation of the teeth.

Finalization of Friendship 4

Many Western chainsaw manufacturers produce tuning kits for their saws to increase power, and service centers have a separate price list with a list of possible modifications. Mainly found in petrol tool service centers in the USA and Germany.

It is also possible to modernize and replace components in order to improve the characteristics of saws from the Druzhba family.

Examples of what can be done:

• Install turbocharging to increase the rate of supply of the fuel mixture;
• Install a more modern carburetor;
• Increase the compression of the fuel mixture;
• Install an electric starter;
• Bore the internal combustion engine and install an enlarged piston;
• Install the decompression valve;
• Leave one piston ring to reduce cylinder running resistance.

In general, the chain saw in question is a paradise for the implementation of engineering ideas. Craftsmen all over Russia assemble various devices, from a boat motor to a bicycle, based on this gasoline saw. We recommend reading an interesting article about what you can make from a Friendship 4 chainsaw with your own hands.

Electronic ignition unit for chainsaw

Despite the widespread use of imported chainsaws, the population, especially in rural areas, still uses many domestic “Druzhba” and “Ural” machines. Both saws have a common drawback that I also had to deal with - the fragility of the electronic ignition unit. This problem is not new - see the article by P. Ivanov “Repairing the ignition unit of a chainsaw” in “Radio”, 2003, No. 2, p. 45. Nowadays it is not difficult to buy a block, but it is expensive and does not last long. I decided to start developing my own design, which I bring to your attention. Unlike the one mentioned above, the ignition unit does not contain remote elements and fits entirely into the original dimensions of the factory unit. The board of the old unit must be removed. The block diagram is shown in Fig. 1. Generator coil L1, ignition coil (high-voltage transformer) T1, capacitor C1, induction ignition pulse sensor L2 and a duralumin base were used from an old ignition unit. The remaining elements are newly introduced. Rice. 1 Schematic diagram of the device When the flywheel rotates, the generator coil L1 generates an alternating current, which, after rectification by the diode bridge VD1-VD4, charges the capacitor C1. At a certain position of the flywheel, a short pulse of positive polarity appears at the terminals of the sensor coil L2, which, passing through the diode VD5 and the current-limiting resistor R1, opens the thyristor VS1. Capacitor C1 is discharged through an open thyristor and the primary winding of the ignition coil T1. Its secondary winding forms a high voltage pulse, which is then supplied to the spark plug. The amplitude limiter of the opening pulse is assembled on transistor VT1, resistor R2 and zener diode VD6. As long as the voltage on the control electrode of the trinistor VS1 does not exceed the stabilization voltage of the zener diode VD6, the transistor VT1 is closed and does not affect the control electrode circuit. When the zener diode VD6 opens, current begins to flow through it and resistor R2. A voltage appears across resistor R2, which slightly opens transistor VT1, which shunts the control electrode circuit of thyristor VS1. As a result, the pulse amplitude is limited to about 4 V at the zener diode indicated in the diagram. This voltage is enough to reliably open the thyristor. In order for the described design to fit into the dimensions of the factory ignition unit, it is necessary to modify the thyristor. To reduce its length, the threaded shank was shortened (1-2 threads were left), the cathode and control leads were also shortened to a length of 4...5 mm. Before shortening the lead, it must be compressed in two places near the body using side cutters with blunt cutting edges. Then, above these places, the lead is bitten off and the cut is soldered with solder. The terminal can be compressed no closer than 2 mm from the SCR body, otherwise the insulator will crack. This compression is necessary to increase the contact area between the internal conductor coming from the crystal and the external terminal of the SCR. The unit is installed using rigid copper wire with a diameter of 0.4-0.45 mm in vinyl insulation. Diodes VD1 - VD4 are assembled closely into a block and their terminals are soldered in such a way that on one side of the block there are AC terminals, and on the other - DC. The transistor is secured with the screw that was used to secure the factory board. A petal is placed under the transistor, to which the leads connected to the body are soldered. Resistors, diode VD5 and zener diode VD6 are soldered to the terminals of transistor VT1 by surface mounting. Capacitor C1 is placed in the same place, and the bridge VD1-VD4 is placed in the same compartment. The wires from coil L1 to the bridge are flexible, of the same cross-section. The wire going to the anode of the thyristor is soldered to its body. Before filling with the compound, the thyristor is held “suspended” on rigid wires in such a way that it does not protrude beyond the dimensions of the unit, and a gap of about 2 mm remains between the thyristor body and the duralumin base of the generator. After testing for functionality, the assembled unit is filled with epoxy compound, making sure that the parts of all elements close to the edges and the SCR housing are covered with a layer of compound. After the compound hardens, the thyristor is rigidly fixed to the base of the generator. The finished block is shown in Fig. 2. Fig. 2 View of the finished block When installing the block in a chainsaw, it may be necessary to adjust the ignition timing. In practice, it was often necessary to set it earlier relative to the factory mark. If you plan to install the block in a Ural chainsaw, before assembly you need to remove part of the mounting protrusion from the back side of the base, painted in Fig. 3 in blue, flush with the base plane. Under the remaining parts of the protrusion, when installing the block in place, it is advisable to place gaskets made of heat-insulating material, such as asbestos cardboard, with a thickness of no more than 0.5 mm. With a greater thickness, the flywheel may interfere with the block parts. Gaskets are needed because the design of the Ural chainsaw provides for the installation of an electronic ignition unit directly on the wall of the engine crankcase, which becomes very hot during prolonged operation. Rice. 3 Reverse side of the part In the above-described block, instead of those indicated in the diagram, you can use diodes KD105G, KD209 with any letter index, as well as other suitable dimensions with a reverse voltage of at least 400 V and an average forward current of at least 0.3 A. We will replace the KS133A zener diode with KS 139, KS 147, KS 156 with letter indices A, B, G or their imported analogues, provided that the sum of the stabilization voltage of the zener diode VD6 and the voltage of the IBE transistor VT1 does not exceed the permissible voltage at the control terminal of the thyristor. SCR KU202N can be replaced with KU202M, KU205V, KU205G. Tri-nistors in a plastic case should not be used due to their insufficient resistance to overheating. In conclusion, I will add that more than 20 blocks were assembled according to the description provided and they work for a long time and reliably. The unit I assembled and installed on my chainsaw 6 years ago has never failed

Forester Income from waste

Chainsaw Druzhba-4 - do-it-yourself repair. Should I choose a chainsaw or an electric saw? How to choose the right chainsaw?

If you are the owner of a Druzhba-4 chainsaw, which sometimes malfunctions, then our article is just for you. We will tell you about more frequent dilemmas presented by the friendship chainsaw 4, the repair of which is possible even at home.

If you are the owner of a Druzhba-4 chainsaw and understand the techniques of working with a chainsaw, which sometimes acts up, then our article is just for you. We will tell you about more frequent dilemmas presented by the friendship chainsaw 4, the repair of which is possible even at home.

Contact ignition on Druzhba is very sensitive to different brands of gasoline and oils and causes a lot of trouble for many. Elements of such ignition are not repairable and are not cheap. We advise owners of old chainsaws to change contact ignition to electric ignition. This will free you from constant problems with its regulation and, as a result, save money. In addition, we recommend reading the article setting up the ignition of the Friendship 4 chainsaw.

If the spark plugs are wet #8212 means the carburetor is overfilling. We fix the problem by slightly bending the gasoline valve inward. This will limit the amount of fuel entering the combustion chamber.

We tighten the fuel screw until it stops and unscrew it three turns; we screw the air screw until it stops and unscrew it two turns. It may be useful to seal the connection between the carburetor and the cylinder to prevent air leaks - another probable reason for the saw to not work. You can use a special sealant or wrap the adapter coupling with a strip of narrow sheet metal. In general, all connections, including gasoline pipes and carburetor membranes, must be sealed; this is the key to high-quality operation of the chainsaw.

For more detailed information about the Friendship 4 saw, read the article Operating instructions for the Druzhba-4m Electron chainsaw.

Gallery

Carburetor. mounted on saws. consists of a housing, the inner part of which is made in the form of an air nozzle (Venturi nozzle). The air drawn in from the engine flows through this air nozzle. The smaller the cross section, the greater the air flow speed, the greater the vacuum. Fuel nozzles are connected to various places in the air nozzle (diffuser), from which fuel is sucked in by the air flow. It is necessary to be extremely careful when adjusting the chainsaw carburetor.

The fuel pump, injector system and adjustment devices for optimal preparation of the air-fuel mixture are integrated, or built-in, into the housing.

Fuel consumption, and therefore engine power, is controlled using the throttle valve.

The pulse cavity of the fuel pump is connected through a pulse channel; low or high pressure controls the pump diaphragm. Thus, the fuel pump operates depending on the engine speed.

For combustion of the air-fuel mixture, oxygen is required, which comes along with the incoming air. To prevent dust and dirt from getting into the drive mechanism and carburetor, an air filter is installed in front of the latter.

Fuel is supplied by the pump diaphragm from the fuel tank through the fuel line, the suction head, the carburetor intake pipe, the pump inlet and outlet valves and the fuel strainer to the inlet needle, and the inlet valve to the diaphragm control chamber.

The inlet needle of the chainsaw engine is connected to the control membrane through the inlet control lever. The cavity under the control membrane is connected to the atmosphere through a hole in the lid. Changes in pressure in the cylinder and crankcase also affect the operation of the carburetor. During intake, a vacuum occurs in the Venturi nozzle, and as a result, depending on the position of the throttle valve, an air flow occurs. In this case, fuel is sucked from the jets and mixed with the passing air.

The fuel is atomized in a diffuser (Venturi nozzle), resulting in the formation of the air-fuel mixture necessary for combustion in the cylinder.

The mixture is fed into the cylinder. Here, individual drops of the mixture evaporate due to high temperature.

The cavity under the control membrane is connected to the atmosphere, so the membrane is pressed upward. At the same time, the inlet needle is lifted from the seat by means of the inlet adjustment lever, and new fuel enters the membrane chamber. Thus, the control membrane is installed so that a constant amount of fuel is drawn in from the jets.

The amount of fuel flowing from the jets into the diffuser can be adjusted by the main adjustment screw and the working mixture adjustment screw when the friendship electron chainsaw is idling.

When the adjusting screws are unscrewed, the mixture becomes richer; when screwed in, the working mixture becomes leaner. The idle speed can be further adjusted by an idle fuel control thrust screw located outside the carburetor crankcase, acting on the throttle shaft lever.

Using adjusting screws, the optimum engine power can be constantly adjusted under different external operating conditions (for example, in the mountains or at sea level). Friendship chainsaw repair is best left to professionals. And don't forget to follow the instructions for Chainsaw Friendship.

Review from a chainsaw owner

I decided to create this topic on our favorite forum, since I couldn’t find anything like it on the Internet - everywhere everyone writes at random and there’s practically nothing about it. So. Before, during and after each use of your chainsaw, you carry out its normal maintenance, which includes such procedures as preparing and filling the fuel mixture and chain oil, adjusting the chain tension, regular cleaning (after each use) of the underframe (sprocket, chain brake, oil supply) and tires with chain, straightening a dull chain, cleaning the air filter and others. But sooner or later your chainsaw. Regardless of the manufacturer's brand, it undergoes some minor repairs. For more than 2 months now I have had an impossibly simple chainsaw from the Ryobi brand (ryobitools.ru) PCN 4040. French assembly and from the same Chinese (like all other saws, including high-profile brands like Shtil and Husqvarna), but Quite high quality parts. Later I found out that this is the twin sister of the HomeLite 4016 saw, only in a different color and with different branded stickers. In general, it doesn't matter.

During this short period of time, 3 malfunctions were identified and eliminated: 1. It became very difficult to start (it would start normally, everything was according to the instructions, but after working for 5 seconds it would stall. 2 times I had to carry out the procedure of completely starting a cold engine - then it would start normally). 2. Dips appeared (even stalling) when accelerating at minimum-medium speed. Initially, when I bought them, they were the same, but somehow softer. 3. At medium-high speeds, the saw began to shake in the hands and simultaneously emit wa-wa with a frequency of approximately 20-30 Hz. The first 2 malfunctions appeared almost simultaneously, and therefore plunged me into shock and confusion. I read a lot on the Internet about carburetors, ignition systems, I even found and downloaded the full details (.) of my saw! I'm afraid to take the saw apart - it's still under warranty. One day my patience ran out and I turned (tightened and unscrewed to the same position) screw L of the carburetor. Screws L and H have plastic end stops (you can't twist them too much - just half a turn each). Hurray, the malfunction of point 2 immediately disappeared! This means the carb was a little unfinished from birth. After that the saw began to accelerate beautifully. But point 1 did not disappear, and at the same time point 3 appeared. I climbed the entire Internet. I also read about tripping (of a single-cylinder engine, about detonation, etc. I replaced the gasoline - it was no use. I spat and removed the top crankcase cover. The air filter was very clogged (sawdust + dust + strengthened with oil). Washed it. Dried it. Started it up - nothing changed. . I unscrewed the spark plug (Champion was screwed in). And purely by accident I broke it (for fun I decided to unscrew the tip - I damaged the central electrode). The spark stopped appearing. I ran to the market to my grandfathers, as usual to motorists - there is no such spark plug! I asked purely by chance from the only one selling power tools there, he unexpectedly got me the same candle, only OREGON's in a package! Naturally, I called him handsome and well done, gave him 100 rubles for it. Came, screwed it in. Started it. Worked and won't stall! Didn't get it. I warmed up the engine a little and turned on the heat. There was a lot of happiness. After that, my girl buzzes smoothly and clearly, as before, does not shake, and at the same time, in addition, she also picks up speed beautifully (dynamically) when you press the trigger.

Read also: Clematis isago photo description

Bottom line: The carburetor was a little unfinished at the factory. Only 1-2 degrees of full rotation. The blockage of the air filter worsened the situation - serious failures appeared in acceleration. This is my fault - the instructions say - regularly check the condition of the air filter! I almost forgot about him. The French decided to save money and introduced cheap Chinese counterfeits of candles from the famous Champion brand. You can see from the candle that this is bullshit. Hence, over time, poor starting appeared and the engine shook at medium speeds; the spark plug began to produce a spark unstably (or a bad spark, I don’t know). Everything has been decided. And further. The material of the air filter is nothing more than the material of commercially available napkins such as pressed cotton wool (sold in every hardware store - multi-colored, and made in almost any city, including our Kislovodsk). So, if you’re too lazy to wash it, you tear off the old one, cut out a new one and glued it on. So I suggest sharing your experience and tricks on repairing and maintaining modern chainsaws!

How to adjust the ignition on Druzhba

The spark on the candle must flash strictly at a certain moment. On Druzhba - when the piston with a portion of the fuel-air mixture approaches the spark plug, not reaching 4 mm from TDC. Only with a precisely adjusted spark point will the engine operate normally. Deviations are called early or late ignition.

With small deviations in one direction or another, the engine will perform worse (lack of power, overheating, excessive fuel consumption, poor starting). With more significant ones it will not work at all. Can shoot into the exhaust system or carburetor.

Mechanical chainsaw breaker Friendship is simply regulated.

Before adjusting, you need to check - perhaps the fastening of the entire system platform has become loose and it has turned. It is checked by matching the factory marks (marks) on the metal base of the ignition and the engine crankcase. As a rule, they are stamped in the form of stripes on the upper right side of the ignition and should match. If there is a bias, it is corrected.

The maximum gap (at the peak of the divergence) between the cams (contacts) should be from 0.2 to 0.4 mm. Ideally 0.3 mm. Checked with a calibrated feeler gauge in the BDC piston position. This gap may increase beyond the permissible limit due to a decrease in the thickness of the contacts (burnout, grinding during cleaning). It is adjusted to 0.2-0.4 mm by turning the adjusting screw using the eccentric, with the pad of the entire breaker loosened.

But a spark occurs at the moment the contacts begin to connect, so its adjustment is more important than the maximum gap at BDC. When the piston does not reach TDC 4 mm, the breaker contacts should begin to diverge. This position is also adjusted by turning the screw using an eccentric. Most often this point is checked visually.

For more precise adjustment, you can use a 12 V indicator light with two wires powered by a battery.

The battery negative is connected to engine ground. One wire of the light bulb indicator is connected to the battery positive. The second wire of the indicator light is pressed against the body of the movable insulated contact. If the contacts are closed, the light shines.

Lightly turn the flywheel by hand. As soon as the contacts open, the light goes out. This is the moment the contacts begin to connect and a spark forms. The piston at this moment should be in a position that has not reached TDC 4 mm.

It is important not to confuse this with the position where TDC has passed by 4 mm.

Running in Chinese chainsaws

Many users will argue - well, well, when it comes to brands: Stihl, Echo, etc. can afford to have high-quality production processes. What about cheap Chinese? The answer is yes, their surface cleanliness may not be at the highest level. Although it should be borne in mind that the same Shtils are also produced in China, which does not make them worse. But often normal operating modes without increased torques (without the tire jamming in the barrel, which should be avoided at any other moment) provide more benefits than “enriching the fuel mixture” or, God forbid, idling.

Modifications

During the entire production of the chainsaw, Friendship 4 has not undergone any major design changes. Let's see what minor changes have occurred in the design of the chainsaw:

1. 1950 - 1960 . The first structural modification concerned a change in the mounting option for the handles; they began to be attached to the fan cover, and subsequently the fastening was moved to the clamp that connected the engine and gearbox.
2. 1960 - 1980 . At this time, a modification of the chainsaw called Druzhba - 4A, which had two main advantages: a contact magneto and the well-known KMP-100 carburetor, entered the assembly line and was produced for 20 years. At the end of the 80s, the modification of the Druzhba -4A chainsaw was discontinued.
3. Late 1980s. Release of the Druzhba-4M Electron modification. Electronic ignition was used for the first time.

4. 1990s . Equipping the chainsaw with a modern (at that time) carburetor KMP-100U. Changes in the saw set - the use of modern type chains.

Many people are confused and say that a number of other changes were made to the Druzhba 4 chainsaw, such as a removable starter, a detachable crankcase and a removable cylinder, but they are deeply mistaken. All these changes were made on the Ural chainsaw, the basis of which was Druzhba.

Ignition system repair

Childhood chainsaw disease Friendship 4 - difficulty starting a hot engine when stopped in operation. The reason for this is a weak and outdated ignition system. To increase the power of the spark at the plug, it is necessary to repair the ignition. Such a repair will correct the situation even if there is no standard coil.

Step-by-step algorithm for repairing the ignition of petrol tools Druzhba 4

1. The high and low voltage windings are removed from the standard ignition coil.
2. Instead of a low-voltage winding, 250 turns are wound onto our coil with special wire (for transformers). You can use PEV2 wire, with a cross section of 0.8-1 mm. We must not forget about interlayer insulation - a new layer of special wires is laid with paper. The beginning of the entire winding is connected by soldering to a standard output to the magnetic core, the other end of the winding is connected with a special mounting wire to the breaker. Then the coil is wrapped with electrical tape or covered with another insulator. The section of the capacitor circuit fed to the coil and the breaker does not undergo changes.
3. Using two wires through a piece of insulating tube, the ends of the connections are made. To prevent short circuits, all the resulting wiring can be placed in one insulating tube.
4. An ignition coil of type B-115 with a removed side resistor is ideal as a transformer. This type of coil is used in ignition of old Soviet Muscovites. It is not recommended to use motorcycle ignitions; they are not powerful enough to provide the required spark. The reel can be fixed to the chainsaw frame using a mounting clamp in any suitable place.
5. The wires from the internal combustion engine are switched according to the following scheme: the first wire, which connects the breaker, capacitor and coil output together, is connected to terminal B-115 with the designation “VK”, the second wire, which comes from ground, connected to the magneto mounting screw, is connected with output B-115 without identification marks. To make the diagram easier to read, it is better to use different colored wires.
6. Finally, the ignition coil is connected to the engine spark plug igniter using a high-voltage wire.

This repair of the ignition system showed an excellent result, the childhood disease of the Druzhba 4 chainsaw disappeared, such a system will work for a very long time.

The only drawback is that the appearance of the chainsaw has changed due to the external coil on the body, and the dimensions have increased. But this is a forced alteration, but the ignition system works reliably and the saw starts at any temperature.

If some points remain unclear, we suggest watching a video on the topic of repairing the ignition of the Druzhba chainsaw.

Device

The main parts of the chainsaw are as follows:

• engine;
• sawing apparatus;
• frame with handles;
• gas tank

The engine is a single-cylinder two-stroke carburetor. Cooled by air flow created by a centrifugal fan. The engine and sawing apparatus are independent units, connected into 1 unit with flange fasteners and secured with a clamp.

When the fuel tap is opened, fuel enters the diaphragm carburetor, which ensures uninterrupted supply to the engine at any angle of inclination and strong vibration. The design of the chainsaw does not allow the engine to stop if the chain gets jammed in the barrel while cutting wood.

The handles are located high, which provides the following capabilities:

• do not bend over while working and get tired less;
• work in deep snow conditions;
• increase user safety.

Technical characteristics table

Below are the technical characteristics of the Druzhba chainsaw; three main versions of the chainsaw were taken for comparison.

Review of the model range of the first Soviet gasoline saws “Druzhba”

The first Druzhba chain saws were not particularly ergonomic and safe, but they were popular and in demand not only in the Soviet Union. They did not have a chain brake, vibration damping system, or chain lubrication. All they had was heavy weight (more than 13 kg) and high power. These chainsaws were used in logging sites, since their main purpose was and remains felling trees and cutting logs of different thicknesses. So, Soviet MashProm released the following modifications of the Druzhba chain saws:

1. Chainsaw “Friendship 2”.
2. Chainsaw “Friendship 4”.
3. “Friendship 4-A”, chain saw.
4. Modernized saw "Druzhba-4A-Electron".
5. Chainsaw “Friendship 4M Electron”.
6. “Druzhba-5E”, chainsaw.
7. “Druzhba-Altai” chain saw.
8. Petrol-powered saw “Friendship 60”.

Let's take a closer look at each modification of these legendary saws:

Chainsaw “Friendship 2”

This chainsaw has a durable aluminum body and is equipped with a two-stroke single-cylinder internal combustion engine with a power of 2200 W, or 2.99 horsepower. Starting the chainsaw manually, from the starting cable. Massive handles are attached to the fan; vibration dampers, chain lubrication and a braking system are still missing. There was only one way to stop the chainsaw - by cutting off the fuel supply to the engine. The length of the saw bar reached 45 cm. The massive appearance and solid weight of the chainsaw (12.5 kg), as well as shortcomings regarding safety, were an incentive for new developments.

Chainsaw FRIENDSHIP 2

Technical characteristics of the “Friendship 2” chainsaw:

Chainsaw “Friendship 4”

Changes have affected the appearance of the saw; now the handles are attached not to the fan, but to the clamp that combines the gearbox and the engine. The weight of the chainsaw remains the same - 12.5 kg. The power of the two-stroke internal combustion engine has increased to 4 horsepower. The photo shows this model; we see two independent units connected together with a clamp: the motor and the saw unit. The tire is 45 cm long. The model is universal; repairs could be carried out even in the field.

Chainsaw “Friendship 4”

Engine characteristics:

• make and model: MP-1 (single-cylinder, carburetor, two-stroke, air-cooled);
• working volume: 94 cubic meters cm.;
• power: 4 hp (2.94 kW);
• maximum crankshaft speed: 5200 rpm;
• Lubrication system: gasoline with oil;
• connection system with saw set: flange connection fixed with a clamp.

Operating instructions for the “Druzhba” petrol saw

This document contains the following information:

1. Device, assembly diagram of the Druzhba chain saw.
2. Technical characteristics of a gas-powered saw.
3. Safety precautions when operating and servicing a chain saw.
4. Preparing for launch.
5. Run-in.
6. Maintenance of the Druzhba chain saw.
7. Malfunctions of the Druzhba chainsaw.

Let's briefly go through the sections:

Chainsaw safety

• do not operate the saw with the air filter removed;
• hold the instrument with both hands;
• use special clothing and protective equipment;
• do not adjust the carburetor if you lack the skills;
• use only high-quality mixture;
• do not work with an empty oil tank;
• do not operate the saw if it is faulty;
• ensure the absence of strangers in the workplace;
• take 10-minute breaks every 45 minutes of work;
• do not use pure gasoline, only when mixing gasoline and oil;
• When replacing the headset, turn off the saw motor.

Where it is located?

The breather on the Husqvarna chainsaw, as in models from different manufacturers, is located in the tank. Sometimes it becomes clogged, which leads to problems with starting the tool or the chainsaw runs intermittently or does not start.

How to fix the problem? Here are several options:

• use a compressor for cleaning;
• Clean the small breather hole with a needle.

In both cases you have to get to this detail. Taking into account the structural features of chainsaws, in order to clean the breather, you will have to remove the handle of the device.