Motoblock Neva valve adjustment

What functions does the walk-behind tractor perform?

The first task set for the walk-behind tractor is to replace manual labor with mechanized labor. A person no longer needs to invest enormous effort in caring for his plot of land. The Neva MB-2 walk-behind tractor will do everything for him.

What functions can this unit perform? First of all, you need to know that a walk-behind tractor is a universal machine. It can perform a huge number of different functions. Thanks to it, you can prepare the soil for planting a new crop in a matter of hours (based on the area of the land itself).

The Neva MB-2 walk-behind tractor can cultivate the land. Its tasks include loosening the soil, removing weeds and snow, digging furrows for sowing and root crops, transporting heavy loads and much more. One walk-behind tractor "Neva MB-2" can replace many other devices that are not so functional. Buying such a unit means saving money and personal time, which are useful for any person.

Description

Spare parts for the Neva MB-2 walk-behind tractor, as well as the unit itself, are produced at the Soviet-era plant CJSC Red October. This is one of the leaders in the domestic market in the production of various agricultural machinery and spare parts for it. The walk-behind tractor, in addition to the basic model, has several modifications that differ in technical characteristics. Most owners of this equipment speak positively about it as a reliable device that never fails.

Setting gaps

Adjusting engine valves means setting the optimal clearances. Their norm is indicated in the technical passport of the walk-behind tractor. Each model has its own acceptable parameters, which depend on the brand and type of engine of the car.

The permissible valve clearance on a walk-behind tractor for a standard unit has the following value:

for the inlet valve - 0.10-0.15 mm;
for output - 0.15-0.20 mm.

To configure them, you need the following tools:

spanners;
probes for 0.10 mm, 0.15 mm and 0.20 mm;
flat screwdriver.

The algorithm for setting optimal gaps is as follows:

The engine must be cold during operation.
Disconnect the oil bath cup from the air filter and the filter element.
Take the key and unscrew the 4 bolts around the protective casing.
Remove the starter, then the walk-behind tractor flywheel protective cover.
Fix the “dead center” on the end of the flywheel. The mark on the cylinder airflow edge must correspond to the zero mark of the flywheel.
Carefully remove the valve cover with the paronite gasket, after unscrewing the 3 bolts.
Check clearances:
There is an inlet valve near the filter;
near the muffler - day off.

To check the interval, insert a feeler gauge between the rocker arm and the valve. If the distance is greater or less than acceptable, use a spanner wrench and a screwdriver to adjust the elements.

Wipe all connections of the mechanism with a clean rag.
Reassemble the structure in reverse order.
Turn on the walk-behind tractor and check its functionality.

If the valves are adjusted correctly, the engine will operate without noise, jerking or failure.

The Neva MB-2 walk-behind tractor is an agricultural unit designed to work on a wide variety of soil types, including previously uncultivated soil.

Available in various modifications with different types of engines:

The main work that can be performed on the Neva MB-2 walk-behind tractor is:

plowing the soil;
cultivation, milling;
watering (pumping station);
hilling;
cleaning areas from grass, snow, etc.;
harvesting potatoes, onions, etc.

Motoblock "MB-2 Neva": instructions for the model range

This type of equipment has many modifications. What is the MB-2 Neva walk-behind tractor? The instructions for the model range include a description of the most popular modifications of this unit. Each model differs from the previous one in power and other parameters. Thanks to this variety, you can choose a walk-behind tractor that will suit all the necessary parameters that meet the owner’s requirements and the needs of the land plot.

"Neva MB-2B 6.0"

This device is equipped with a foreign-made Briggs Stratton engine, which deserves respect for its performance qualities. A motor with a power of six horsepower is perfect for ordinary work on the site. The working volume of this unit is two hundred and five cubic centimeters, which is not such a good result compared to other, more powerful modifications of the Neva MB-2. The fuel tank, which has a volume of about four liters, can be filled with ninety-second or ninety-five gasoline. The fact that it has eight cutters makes it possible to cultivate a strip of land up to one hundred and thirty centimeters in width. Because of this, his productivity is very high. Such a machine weighs about one hundred kilograms.

Repair of the Neva walk-behind tractor: how to do everything right without the help of specialists

If you have access to a huge selection of necessary spare parts, then, of course, it is easier to make gearboxes yourself. But please note that such a spare part requires serious metal processing equipment. If you have this, then you can choose a housing with optimal parameters, make holes for the shafts on the bearings and make the device no worse than at the factory.

Initially, you need to calculate the rated power without errors. Thanks to the correct results, you will be able to find out the optimal angle to find for a bevel gear. You need to calculate the number of rotations in 60 seconds.

The completed gearbox requires determination of its operating conditions, including the load. Its functioning will be at the highest level if the temperature and lubricant are chosen correctly. The next step is to assemble the gearbox. The case can be taken from the factory. According to its diameter, you can determine the bearing housing for the shaft. A caliper and a drill will help you with this.

A steel flange must be mounted on the front side of the gearbox. Inside we mount a flange bearing and a washer. The flange is secured with screws at the generator itself. The key and gear must be selected in advance. All components that are in contact with the transmission system are fixed to the rotary generator.

Operating manual Neva MB-1

First, it should be noted that among the many models of this manufacturer, it is MB1 and MB2 that are considered the most famous and widespread. Using their example, we will deal with common malfunctions.

If the owner of a walk-behind tractor notices an oil leak on the output shaft, he immediately needs to remove the axle shaft covers and replace the cuff;
If the gearbox is jammed, the mechanism should be disassembled and the unsuitable chain should be replaced;
If there is no kinematic connection in the gearbox, you must not hesitate and update the sprocket in the block;
Problems with gears can occur as a result of the destruction of the shift holder or due to the cut threaded part of the shift knob. To get rid of problems, it is worth replacing damaged parts;
When the overrunning clutch starts to act up, it becomes obvious. You should remove the starter, take out the clutch and grind off the grooves for the balls. By pouring a little high-quality oil inside, you can minimize the friction of the coupling and shaft.

The focus was on the most common problems. Thanks to the instruction manual, you can easily understand the features and carry out repairs yourself.

If the owner of the unit is faced with the impossibility of separating the axle shafts, he needs to check the drive adjustment and change the cable tension;
Self-switching of gears is often the result of a malfunction such as a violation of the shift control system. Then you should reduce the tension of the screws holding the board, engage 1st gear and again tighten the screws as much as possible;
If there is no kinematic connection in the gearbox, it is necessary to update the shift fork.

Operating manual MB 2 (2013 version for new models)

Operating manual Neva MB-2 (1992 version for older models)

Solutions to other problems and more detailed information about using the walk-behind tractor can be found in specialized operating manuals designed for new and old devices.

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"Neva MB 2B 6.5"

This model is similar in almost all respects to the Neva MB-2B 6.0 walk-behind tractor. The last index “6.0” shows the engine power. The Neva MB-2B 6.5 unit has an engine power of six and a half horsepower. The motor of this equipment is more powerful than that of the previous modification, which makes it more efficient.

"Neva MB-2K-7.5"

The engine on this unit is already from the domestic “ZAO”, the power of which reaches seven point five horsepower. The engine displacement of this beauty is three hundred and seventeen cubic centimeters. This walk-behind tractor is a powerful unit for plowing fields that will never let its owner down. The only drawback that the Neva MB-2K-7.5 has is its small three-liter fuel tank. You have to constantly add fuel, because under heavy loads (ploughing) it quickly runs out.

Motoblock "Neva MB 2": operating instructions

Do not forget that it is still better to take care of your unit and not bring it to a faulty state. Operating the Neva MB-2 walk-behind tractor is a delicate matter. You need to feel when to stop and when you can continue working. In order not to overheat and overwork the engine, it is best to give your car a rest every couple of hours. You should always monitor the oil level. The quality of the oil itself is also important - if it is bad, then the parts will wear out quickly, and then you will need spare parts for the Neva MB-2 walk-behind tractor. Fortunately, spare parts for it are not that expensive.

Clutch, levers, cables

Clutch cable for Neva walk-behind tractor

The Neva walk-behind tractor is equipped with several simple elements: levers and cables. The number of engine revolutions depends on the operation of the gearbox lever and all connecting cables. Such a device tends to wear out and fail during operation. Therefore, they should be periodically checked for integrity and replaced if necessary.

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Also, don’t forget about the clutch. It fails much less often, but the plug should also be inspected periodically. If necessary, all these parts are freely available in the store.

Some people think about not buying a new cable, but making one from improvised materials. But it’s better not to experiment with this part and buy a new one. Because it cannot be replaced equivalently. The only temporary replacement option is to take it from a car clutch or scooter.

Features, pros and cons

The Neva MB 2 walk-behind tractor is one of the most popular units of this type. It is versatile and has excellent technical characteristics. Ideal for working in private farms, vegetable gardens, and orchards.

There are engines with markings:

The letter “2K” means that the walk-behind tractor has an engine made in Russia , it has a good service life and an average price. The single-cylinder engine has a power of 6.1 and 7.6 liters. With.

Much depends on what kind of unit it is: DS 1 or DS 2. The first can run on 76-grade gasoline, DS 2 requires 95-grade fuel. On average, gasoline consumption is about three liters per hour if the walk-behind tractor is almost 100% loaded.

The walk-behind tractor with the letter “2B” has an imported power plant (most often Briggs & Stratton). Such mechanisms are considered to be the most reliable. Model “2C” on such models there is a Japanese “Subaru” engine with a power of up to 7.1 liters. With. Diesel options have more power.

Japanese technology requires proper configuration, only then will it work without failures. Before buying a Neva walk-behind tractor, you should understand what kind of work it will do.

If the plot at the dacha is too large, more than 16 acres, then the engine should be chosen at least 9-10 liters. With.

“Neva MB-2” is fixed on the frame, and various equipment can be assembled there. The power plant is equipped with a gearbox with six gears, this is a significant help in processing even the most dense soils.

The machine can move at speeds of up to 10 km per hour, and even large heavy loads can be transported. The walk-behind tractor has four speeds, 2 of them are rear. The controls are very convenient, mounted on the steering wheel.

The V-belt drive can quickly rearrange the pulley, lever and belt. The unit is well equipped; there are cutters for a wide variety of purposes.

The device weighs only 99 kg and is compact in size. It can be transported over long distances in the trunk of a car.

The machine can do the following work:

plow;
sow;
to harvest;
serve in public utilities;
work like a pump.

Main parameters:

depth of penetration into the soil up to 21 cm;
the grip can be realized up to 130 cm;
The set includes 6 cutters;
turning radius 112 cm;
cutter diameter 37 cm;
traction force 172 N;
dimensions LxWxH, meter – 1.75 by 0.66 by 1.4;
operation is permissible at temperatures from – 26 to +39 degrees Celsius.

In the cold season, it is necessary to drain the “summer” oil and fill in the “winter” oil. It is unacceptable to use the wrong oil, this will lead to damage to the unit, the same statement applies to fuel. American power plants are extremely picky about the purity of gasoline. It is better to filter domestic fuel before pouring it into the tank of a walk-behind tractor.

The unit service package includes:

running in the engine and tuning it;
adjustment of gearbox and transmission;
adjustment of attachments;
preventative maintenance and testing;
timely oil change.

The main problems of operating the Neva MB walk-behind tractor

The fate of the walk-behind tractor has so happened that each of the components requires regular attention and periodic maintenance, regardless of which engine is installed on the unit. But even Subaru and Briggs engines require periodic washing and adjustment of carburetors during operation, cleaning the needle valve seat from accumulated dirt, and cleaning the spark plug.

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Gearbox and V-belt drive

The next most important unit of the walk-behind tractor is the gear-belt reducer. The mechanism consists of two parts - a gear reducer and a V-belt drive. The walk-behind tractor gearbox is assembled in a light alloy housing and filled with oil. According to the instructions, the oil is changed after the first 200 hours of operation. There are no problems with oil, TAD17i is suitable, there are problems with deformation and splitting of the gearbox housing, rapid operation of sealing seals and leakage. The gearbox provides two forward and one reverse gears. Two more gears are obtained by reversing the V-belt drive belt.

Experts recommend changing the oil not according to the instructions, but after the first 40 hours of operation, with mandatory flushing of the crankcase and replacement of rubber seals with imported ones.

According to the instructions, the belt of the Neva-2 walk-behind tractor should be of standard A1180 - A45. This is the most consumed and worn part of the transmission, since instead of the traditional disc clutch, which even the Chinese often install on their Zubrs, the Neva uses a V-belt clutch, which is already more than a hundred years old. It is clear that the service life of such a mechanism is ten times less than the ferrido system.

According to the instructions, the clutch works as follows:

When you press the lever-handle, the force is transmitted through a flexible cable to the tension roller, which tensions the belt and picks up the slack, ensuring traction of the narrow side belt drive with the cheeks of the pulleys;
When the lever is released, the return coil spring increases the slack and loosens the belt's grip on the pulleys.

But unfortunately, regularly stretching the coil spring to its maximum leads to its weakening, and, as a result, burning of the belt at maximum speed. Therefore, during operation, you have to regularly stop the walk-behind tractor to adjust the belt tension according to the instructions. According to the instructions, the deflection of the belt in the center when pressed with a force of 5 kg should not exceed 9-10 mm.

Motor DM-2

To operate the walk-behind tractor, according to the instructions, use pure unleaded gasoline of the A-92 brand. If you use a clean canister for intermediate storage, and be sure to settle the fuel before starting operation, and do not fill the last 100-150 ml into the tank, but carefully drain it for other purposes, then there should be no problems with the operation of the engine.

The most painful part of a walk-behind tractor engine is its carburetor. Not only is it almost impossible to adjust the operation according to the instructions, but even at the factory settings the needle does not lock and regularly pours fuel into the intake tract. Accordingly, after 20-30 hours the engine oil in the crankcase turns into a stinking slurry.

According to the instructions, M10GI mineral oils are used to fill the engine crankcase; in practice, semi-synthetics and synthetics are used, for example, 10W40 approximately 1.3 liters. For the gearbox, the instructions require filling 2.2 liters.

To start the engine according to the instructions, you need:

Open the tap, pump fuel into the carburetor and move the pump foot to the starting position;
Hole a couple of times with the damper open;
Close the throttle completely and start the engine.

Of course, when the walk-behind tractor engine is hot, it is started with the throttle open.

Plow adjustment

In order to obtain the required plowing depth and blade direction, you need to know how to set up a plow on a walk-behind tractor. According to the instructions, the plow is attached to the hitch using an adjustable bracket and kingpin. Installation and adjustment of the plow is carried out in two stages.

At the first stage of operation, the installation height of the plow is adjusted; for the Neva, the vertical bar must be installed higher and lower in the row of finished holes. The optimal height is 7-9 cm.

After trial operation of the plow, you will need to set the angle of attack of the cutting edge. To do this, according to the instructions, the walk-behind tractor, shod with lugs, is installed on a flat surface. A 15 cm high stand is placed under the left wheel, and by turning the fastening head the inclination of the cutting edge to the coating surface is adjusted.

Device

The power plant has an overhead valve arrangement, the crankshaft is located in a horizontal position, which allows it to create significant torque. Motoblocks "Neva" for the most part are equipped with this particular unit produced in St. Petersburg. The second most popular is the unit from Subaru (Robin-Subari EX21), which also has a power of 6.6 liters. With. Motoblocks "Neva" are mounted with Briggs Stratton engines (power 5.6 hp).

Domestic walk-behind tractors with a DM-1K engine can have modifications of 6.2 and 7.5. The first is oriented on 76 grade unleaded gasoline, the second is designed for 92 grade gasoline.

Over 35 years, many different modifications of Neva walk-behind tractors have been produced, however, the main spare parts of the unit are standard, which makes maintenance easier; spare parts can always be found on the market. The bearings are reliable and ensure smooth operation of the gear. The decompressor operates automatically and is an integral part of the unit. The air filter has two assembled blocks.

The engine consumes a small amount of fuel, creating a small amount of noise. The spark plugs ensure uninterrupted ignition operation; the engine can be started even in conditions of high humidity at any temperature.

"Neva MB 2" has dimensions:

length 1742 mm;
width 652 mm;
height 1310 mm.

The track width is 322 mm; if you take into account the axle extensions, the size can reach 570 mm. The ground clearance of the walk-behind tractor is 142 mm. The cutters have a diameter of 36.2 cm; tillage in depth can reach 22 cm.

Basic faults

Belt adjustment and dimensions

For the Neva MB-2 walk-behind tractor, the A-1180 drive belt is used. This model uses one belt that provides forward movement.

In other modifications of the Neva MB-2 model, two drive belts are used. Reverse gearing occurs in the gearbox itself.

Replacing the belt for MB-2 walk-behind tractors is carried out in the following sequence:

The shield is removed, and then the pulley protective cover.
The spring from the walk-behind tractor rod is removed to loosen the belt.
The screws securing the bracket are turned.
The bracket rotates to a position in which the limiting pins do not prevent the part from being removed from the pulley.
The pulleys are adjusted, and then a new belt is installed.
Pull the belt onto the gear shaft pulley, and then onto the motor pulley.
In reverse order, place the remaining parts in their places.

Replacement of gearbox seals

The oil seals in the Neva MB-2 walk-behind tractor are replaced if an oil leak is detected.

This condition is dangerous because the walk-behind tractor gearbox may be left without oil, and this will lead to rapid wear of the unit.

The sequence for replacing oil seals is as follows:

Remove the cutters from the shaft, cleaning the shaft and covers from dirt and oil residues.
Unscrew the cover bolts, tap off the oil and debris, and remove the cover from the gearbox.
The old oil seal is replaced with a new one and wiped dry.
The cover is returned to its place (if necessary, it is placed on sealant) and fixed with bolts.

Adjusting and tuning the Neva MB-2 carburetor

The functionality and durability of the walk-behind tractor engine depends on the stable operation of the carburetor. This is why its adjustment and tuning are so important. In addition, if the carburetor is incorrectly configured, a gasoline walk-behind tractor may experience increased fuel consumption

The carburetor of the Neva MB-2 walk-behind tractor is adjusted as follows:

The full throttle and idle screw are turned to the limit.
Both screws are unscrewed 1-1.5 turns.
Next comes starting and warming up the engine.
The throttle control lever is placed in a position in which the engine will operate at minimum speed.
Set the minimum idle speed until the unit operates stable.
The idle speed is set to maximum.
The minimum idle speed is adjusted.
Steps 6 and 7 are performed until the engine runs smoothly (more smoothly by ear) at idle speed.

For long-term and uninterrupted operation of the walk-behind tractor, it is necessary to regularly perform engine diagnostics, monitor the frequency of oil changes, and also comply with operating conditions and time intervals for scheduled maintenance.

Adjustment of valves

Adjusting the valves is a fairly simple procedure that requires wrenches, screwdrivers and a feeler gauge. The valve adjustment process is needed to establish optimal and technically correct clearances between the valves of a walk-behind tractor engine. Adjusting valves using the example of the Neva MB-23 walk-behind tractor (the principle is the same for everyone)

The adjustment sequence is as follows:

remove the casing that covers the engine;
remove the valve box cover;
make adjustments (see below);
Reinstall the valve box cover;
Replace the casing.

The valves are located under the valve cover. The gap size can be checked with a feeler gauge. The intake valve clearance is 0.15 mm, and the exhaust valve clearance is 0.2 mm. The dipstick should fit under the valve with the correct gap size.

To adjust, the valve nuts are loosened, then a feeler gauge is inserted, after which the adjustment itself is made, and the valve nut is tightened.

The manufacturer emphasizes that in Neva MB-2 walk-behind tractors, the gaps between the ends of the valves and the ends of the pushers (0.1÷0.2 mm) are ensured by grinding the ends during the initial assembly of the engine and are not adjusted during operation!

Checking and adjusting the clutch of the Neva MB-2 walk-behind tractor

The main function of the clutch is to connect the gearbox to the engine, disengage it, and also connect other operating devices to the engine. If an overload occurs during operation, the clutch begins to slip - this is how other parts of the walk-behind tractor are protected from damage.

Checking the clutch operation can be done according to the diagram below.

If the clutch lever is in the disengaged position, the clutch cable is loose. Consequently, the tension roller lowers and comes into contact with the drive belt. After which the drive belt and small roller move to the lowered position - this stops the supply of power from the engine to the transmission.

When the clutch lever is moved to the "ON" position, the clutch cable pulls the idler pulley, therefore the bottom of the belt is pressed tightly, the small pulley moves the large pulley and power is transferred.

Models

"NEVA MB2 MultiAGRO"

This is a new model that can rightfully be called one of the most successful. The unit stands out from the line with rich functionality, as well as a good Briggs&Stratton engine, which belongs to a separate Vanguard series. Supplemented with an excellent gearbox with original characteristics.

The engine resource is designed for five thousand hours, which is a record among power plants of this class . The walk-behind tractor has two forward gears and one reverse gear. The traction force is about 142 N, which allows you to work on virgin soil and transport heavy loads.

The walk-behind tractor has a single-cylinder four-stroke engine. It features economical fuel and oil consumption. Any attachment is suitable for this walk-behind tractor.

Set:

walk-behind tractor "Neva MB-2B-6.5" 1 pc.;
cutters 4 pcs.;
wheels (4.6x10) 2 pcs.;
axle attachments 2 pcs.

"NEVA MB2 B"

6.5 l. With. Suitable for a wide variety of jobs. Such a unit is indispensable in auxiliary communal services. This walk-behind tractor is equipped with a four-stroke Vanguard engine, which has a number of original improvements:

more modern carburetor layout;
the gearbox has several additional stages;
there are big wheels.

The processing strip is 82 cm; if additional cutters are installed, the strip increases to 126 cm.

"Neva MB-2N GX200"

Makes it possible to cultivate the soil and clean streets and squares. The power of the unit is enough to cultivate virgin lands.

The gasoline engine is from, has a cast iron body, power is 4.2 kW. The machine has increased traction parameters.

"Neva MB2 GX-200"

It cannot rightfully be called a heavy unit. Maneuverability, maneuverability and power are noticeably above average.

The unit is distinguished by its unpretentiousness and high productivity. Maneuverability is achieved by locking the wheel. You can install eight cutters, the track width can be up to 172 cm. It can be combined with any attachments.

Characteristics:

the weight of the device is just over one hundred kilograms;
the fuel tank holds up to 3.2 liters of gasoline (92 or 95);
there are two gears;
the soil can be cultivated at a depth of 21 cm;
shaft revolutions in first gear are 22-43;
shaft revolution in second gear 88-161;
The gearbox is enclosed in an aluminum housing.

"Neva MB 2S-7.5PRO"

Another popular walk-behind tractor model. The machine is distinguished by its ability to work in any weather and temperature. The gearbox has a chain and gears, which contain a double-groove pulley. The device is very maneuverable, its wheels work autonomously. There is a function to turn off one of the wheels. The ground can be processed with eight cutters, the working width is 171 cm.

The equipment is capable of performing almost any job, characteristics and types of work:

cleaning the area;
transportation;
harvesting root crops;
mowing;
with Subaru engine;
the amount of fuel in the container is 3.5 liters;

total weight 101 kg;
aluminum body;
width of cultivated soil 171 cm;
processing depth 21 cm;
shaft revolutions 22-43 (1st gear) 88-161 (2nd gear).

"Neva MB 2S-6.5PRO"

This is a classic unit that has proven itself from the best side. "MB 2C-6.5PRO" is versatile and can work with any soil. Power is 4.7 kW (6.4 hp). It is possible to install up to eight cutters; the width of the cultivated soil strip can reach 172 cm. It is distinguished by high maneuverability even during high loads.

You can change the speed by moving the pulley. It is possible to block the left wheel, which makes the unit more maneuverable when turning.

Main characteristics:

suitable for transportation;
cultivation of all types of soil;
public works;
horsepower 6.1 (4.5);
the tank holds 3.5 liters of gasoline;
the device weighs about a hundredweight;
two forward gears and one reverse gear;
gasoline 92 and 95.

"Neva MB 2B-6.5 RS"

This walk-behind tractor is equipped with a gasoline engine from the Briggs&Stratton I/C series. This is one of the best units that can successfully cope with the most complex tasks, performing almost any type of agricultural work, the soil may be different. Designed for processing medium and large sized areas. Additionally, the walk-behind tractor has an electric starter and headlights. It features increased performance, the engine is 6.21 liters. With. (4.5 kW).

The unit has good functionality, reliability, and the mechanism can withstand heavy loads.

Main advantages:

you can work in different gears, the pulley is simply redirected to the second cell;
there are unlockers, they are provided with maneuverability by the mechanism;
there is a light source, which allows you to work in the dark;
fuel capacity 3.9 liters;
weight 98.5 kg;
two gears - forward, one reverse;
engine capacity 204 cc. cm;
fuel – gasoline 92 and 95;
width of the cultivated strip is 85-128 cm;
shaft speed 22-43 and 88-162;
immersion in the ground up to 21 cm.

Gearbox, faults, device

Below is an algorithm for setting up a carburetor on a Neva walk-behind tractor with a Subaru engine.

Carburetor adjustment diagram

The diagram shows three screws that are responsible for the amount of fuel supplied.

Screw 1 - number of full throttle revolutions;
Screw 2 - number of idle speeds;
Screw 3 - responsible for idling.

To adjust the carburetor, you must perform the following manipulations:

Tighten screws 1 and 2 until they stop;
Then unscrew them about 1 turn;
Turn on the ignition and warm up the engine;
Then place the throttle control lever until the engine is turned off (that is, until the speed is at a minimum level);
Set the minimum idle speed level with the third screw;
Then set the maximum idle speed with the second screw;
If necessary, adjust the minimum speed again by adjusting the position of the third screw;
Carry out the last two steps until stable engine operation is obtained;
If there are interruptions, tighten the first screw again until it stops and unscrew it one and a half turns.

The gearbox is designed to transmit rotation that comes from the engine to the wheels and attachments. It regulates the speed and direction of movement.

Gearbox of the Neva walk-behind tractor

The gearbox is designed in such a way that to regulate its operation there is no need to disassemble the entire mechanism. All regulators are located on the outside.

The gearbox has 5 positions. When you press the lever, the clutch is disengaged; when it is released, it returns to its place.

If the drive is connected to the right axle shaft, then at this moment of switching the walk-behind tractor stops. When the handle is recessed, the left sprocket catches and the gear shifts down. If it is necessary to increase the gear, the handle moves forward.

The clamps or springs have failed. In this case, they should be replaced with new ones;
The settings of the gearbox itself have gone wrong. Loosen the screws, set the first gear, and tighten it back;
Oil appears on the shaft. The main reason for this behavior is the failure of the cuff. It needs to be replaced with a new one. It is also recommended to replace the seals. To do this, just pry off the old ones, pull them out and install new ones;
The transmission is jammed. There's a problem with the chain. It should be inspected and, if its integrity is damaged, replaced with new ones;
The transfer is not recorded. Most likely the fork is worn out. It cannot be repaired, only replaced with a new one.
Grinding noise in the gearbox. Most often it occurs with increased loads on the walk-behind tractor. This indicates that the gearbox axle shaft has failed, or the drive belt tension needs to be changed.

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Brief video review of the Neva walk-behind tractor gearbox: design, disassembly, repair

Instructions for assembly, operation and repair of the NEVA MB-2 walk-behind tractor

The walk-behind tractor, under the “Neva” logo known to rural workers, belongs to the category of small-sized agricultural equipment produced in St. Petersburg. In fact, this brand of mini tractor is not new to gardeners and amateur gardeners. "Neva" was put into serial production back in the mid-80s. The walk-behind tractor of this brand has become a “pioneer” in the domestic market of small equipment for rural areas. Throughout this time, to this day, this model has only been modernized and improved.

Tow hitch for a walk-behind tractor with a plow

Motoblock device

Today it will be no secret to anyone that the MB 2 unit is the most popular equipment among lovers of rural work and is in great demand . The walk-behind tractor of this line is available in several modifications, differing from each other by engine brand. These include:

a model with the 2K index, equipped with a motor from a domestic manufacturer with a long service life and a fairly low price;
“Neva” with the designation 2B - mini-tractor is equipped with an imported engine, mainly from Briggs & and Stratton;
modification 2C, equipped with professional elements for processing land balls from the manufacturer EX Robin Subaru.

Gearbox of motoblock Neva MB 2 diagram