Checking the serviceability of the centrifugal clutch of the walk-behind tractor. Motoblock clutch. How to make a clutch mechanism with your own hands

The clutch is tightly interconnected with the gearbox. It performs quite important functions. Namely, it transmits torque from the crankshaft to the gearbox located in the transmission, disconnects the gearbox and the crankshaft (this is done when shifting gears). And this mechanism also ensures the smooth running of the walk-behind tractor from a standstill. Thanks to him, it is possible to stop the equipment without turning off the engine (this is possible through the clutch lever, cable and the entire system as a whole).

What types exist

Depending on the design features walk-behind tractor, the mechanism in question can be of the following types:

frictional;
hydraulic;
electromagnetic;
centrifugal;
single disk;
two-disk;
multidisk;
belt.

A centrifugal clutch is used to solve various problems, one of which is to facilitate the control of a walk-behind tractor. The clutch provides a smooth start of movement, since the pressure on the clutch disc is automatic.

It includes the following accessories:

clutch cable;
flywheel;
release bearing;
switching lever;
clutch lever mounted on a walk-behind tractor;
transmission input shaft;
driven disk;
pen;
lock washer;
stem fungus;
shutdown plug.

By the way, if the owner of the walk-behind tractor does not have experience in plumbing, then he will not be able to make a clutch with his own hands. You can only replace or repair it.

The important role of the differential

Since this mechanism is part of the transmission, it means that it is associated with the clutch. The differential has a difficult purpose - the implementation of smooth turns, as well as improving the maneuverability of heavy walk-behind tractors. The purpose of the clutch for the walk-behind tractor and the differential is to adjust the rotation of both wheels at different speeds. In addition, power transmission mechanisms can be equipped with wheel blocking functions. However, instead of a differential, it can be set special device, which allows you to turn off one wheel while driving.

Extensive functionality

The grip on the walk-behind tractor is of great importance when driving. Without it, it is difficult to move off, although it is possible. If it is out of order, then it is better to immediately repair it. A broken clutch for a walk-behind tractor in a manual gearbox leads to damage to the entire transmission. In this sense, the centrifugal clutch has proven itself better, since it has found application in automatic boxes gears. If it fails, then the walk-behind tractor will not budge at all, which means it will not entail other breakdowns.

The composition of the centrifugal clutch for a light walk-behind tractor includes:

flywheel;
hub with locking groove and key;
pulley;
flange;
bearing;
sleeve;
retaining ring;
casing.

Making a clutch for a heavy or light walk-behind tractor with your own hands requires certain knowledge and experience. If you have them, then start right now. For reliable operation of the centrifugal type, it is necessary to reduce the weight of the pads to 110 grams. Initially, each of them weighs 134 grams. It is necessary to remove the rubber rings from under the pads, and install rigid springs in their place.

Motoblock controls

This is a system of mechanisms that allows you to change the speed, as well as the direction of movement of the walk-behind tractor. The controls include the steering wheel, clutch and shift levers, throttle position knob and more. Since the walk-behind tractors do not provide a seat for the operator, it means that the maneuvering of such equipment is provided with the help of hands. But, if you can buy a trolley with a seat in a specialized store, you get a mini-tractor.

The clutch of a walk-behind tractor is one of the important elements of the transmission. It provides separation of the motor and gearbox during the process of switching speeds. Due to this, the walk-behind tractor starts a smooth movement from a place, and it is also ensured that it stops without completely turning off the motor. How to properly adjust the clutch on a walk-behind tractor is indicated below. If it is easier for you to perceive information visually, then you can refer to the youtube channel of the AgroMotoCentre company, where video reviews of products are posted, as well as advice on how to use them. correct use. To watch the video go to link.

The principle of operation of the clutch

The clutch design for a walk-behind tractor includes several important elements such as control devices, a leading element and driven parts.
The design of the leading part includes the driven and friction discs. Springs are located along the perimeter of the pressure plate cylindrical shape. With their help, the disk they pick up is compressed. In this case, the other end of the spring is in contact with the casing. The control mechanism is made from the release levers, which are connected to the body of the pressure plates with the help of a layer and a lever.

clutch adjustment

The clutch is the link between the gearbox and the control lever, so you need to know how to adjust the clutch on the walk-behind tractor.
When the clutch fails, its failures are immediately visible:

in this case, the clutch is completely squeezed out, and the walk-behind tractor is torn from its place. To fix these problems, tighten the adjustment screw;
if the clutch is in the released state, but the walk-behind tractor still does not give the desired speed or stands still, then it is necessary to loosen the screw.

If a strange sound is heard from the gearbox during use, immediately stop all work. The most common problem is insufficient oil or poor quality. The oil level must be checked each time before starting work. If the oil is changed, but the noise does not stop, then you need to contact the service center for diagnostics.
If problems with gear shifting are found, the causes must be sought in the correct clutch setting, worn gearbox parts or worn shaft splines.

Knowledge about correct adjustment clutches on the walk-behind tractor will ensure your safety and efficiency of the work process. To purchase new products, you can go to!

The walk-behind tractor consists of the following main components: engine 1, transmission 2, running gear 3 and controls 4.

Engine and its support systems

The motoblock drive is a classic internal combustion engine with all the systems necessary for its operation. In light and medium class cars, four-stroke gasoline engines are used (see about the design and operation of a four-stroke engine). Heavy-duty motoblocks are often equipped with diesel engines. In obsolete and some lightweight models, you can sometimes (rather rarely) find a two-stroke gasoline engine.

The device of a four-stroke gasoline engine (Honda) of a walk-behind tractor: 1 - fuel filters, 2 - crankshaft, 3 - air filter, 4 - part of the ignition system, 5 - cylinder, 6 - valve, 7 - crankshaft bearing.

Most motoblock users have to deal with four-stroke gasoline engines air cooled. These engines have the following systems to ensure their operation:

A fuel supply system designed for preparing an air-fuel mixture, consisting of a fuel tank with a cock, a fuel hose, a carburetor, and an air filter.
Lubrication system that provides lubrication of rubbing parts.
A starting mechanism (starter) designed to spin the crankshaft. Many engines are equipped with an easy start mechanism that reduces the starting force by using a device on the camshaft that opens the exhaust valve on the compression stroke and thereby reduces the compression in the cylinder when the crankshaft spins up. Heavy walk-behind tractors are sometimes equipped with battery-powered electric starters. Some models have electric and manual start. The latter is used as a backup.
A cooling system that removes heat from the engine cylinder block by a stream of air pumped by the flywheel impeller when the crankshaft rotates.
An ignition system that ensures uninterrupted sparking at the spark plug. A rotating flywheel with a magnetic shoe induces an emf in the magneto, which is converted by an electronic circuit into electrical signals supplied to the candle. As a result, a spark jumps between the contacts of the latter, igniting the air-fuel mixture.

1 - electronic magneto, 2 - screw, 3 - magnetic shoe.

The starting mechanism and ignition system of the Cascade MB6 walk-behind tractor: 1 - starter handle, 2 - fan housing, 3 - protective casing, 4 - cylinder, 5 - cylinder head, 6 - magneto, 7 - flywheel.

The gas distribution system responsible for the timely entry of the air-fuel mixture into the engine cylinder and the release of exhaust gases. The composition of the gas distribution system includes a silencer designed for the directed release of exhaust gases and noise reduction.

Note that engines are sold with all its systems, and if there is an idea to make a walk-behind tractor with your own hands, then the purchased engine will already have a gas tank, an air filter, a starter, etc., for example, here (only it’s better to buy through the Internet store, because in a regular store of this network, the price may be higher).

The figure below shows the Honda GX series engine of the GX200 QX4 model, which is widely used in domestic-made walk-behind tractors. The power of the unit is 5.5 hp. It has a horizontal crankshaft and a high compression ratio for efficient fuel combustion and low carbon deposits.

Transmission

The transmission is used to transmit torque from the engine to the wheels and change the speed and direction of movement of the walk-behind tractor. It usually consists of several units connected in series with each other: a gearbox, a differential (in some models), a clutch, a gearbox. These elements can be structurally performed as separate units or combined in one housing. The gearbox serves to switch speeds, which can be of different numbers (up to 6 forward and 2 rear), and at the same time is a gearbox.

By their type, transmission units (reducers and gearboxes) can be gear, belt, chain, or various combinations of both.

classical gear transmission, consisting only of cylindrical and bevel gears, is used mainly on heavy walk-behind tractors and some models of medium machines. As a rule, it has a reverse and several lowering steps.

The figure below shows the gear transmission of the Ugra NMB-1 walk-behind tractor, consisting of cylindrical and bevel gears. The engine is rigidly attached to the gearbox, which in turn is rigidly connected to the bevel gear. The design of the NMB-1 walk-behind tractor does not have chain and belt drives, which, according to its developers, are an unreliable link in transmissions due to the tendency to break, damage and belt slippage.

Scheme of the gearbox of the Ugra NMB-1 motoblock: 1 - Clutch fork, 2 - Retaining ring, 3 - Adjusting ring, 4 - Bearing, 5 - Retaining ring, 6 - Adjusting ring, 7 - Retaining ring, 8 - Cuff, 9 - Retaining ring, 10 - Bearing, 11 - First gear and reverse gear, 12 - Second and third gear, 13 - Adjusting ring, 14 - Bearing, 15 - Driven gear shaft, 16 - Driving gear shaft.

Scheme of the angular gearbox of the Ugra NMB-1 (N) walk-behind tractor: 1 - Locking ring, 2 - Adjusting ring, 3 - Bevel gear, 4 - Adjusting rings, 5 - Bearing, 6 - Intermediate gear shaft, 7 - Upper housing, 8 - Output shaft, 9 - Adjusting rings, 10 - Bearing, 11 - Bevel gear, 12 - Retaining ring, 13 - Boot cup, 14 - Boot, 15 - Cuff, 16 - Adjusting rings, 17 - Lower housing, 18 - Adjusting gasket, 19 - Bearing, 21 - Cover, 22 - Gear, 23 - Gear, 24 - Shaft.

The torque from the crankshaft is transmitted to the drive shaft 16 (Gearbox Diagram) of the gearbox and is removed from the bevel gear of the driven shaft 15 by the vertical shaft 6 of the angular gearbox (Angular Gear Diagram), which transmits rotation to the hexagonal shaft 8 of the drive wheels. To avoid violation correct operation transmission, it is not recommended to disassemble the walk-behind tractor transmission, which can lead to a misalignment of the gears.

The gearbox by its design is mechanical two-way with 3 gears forward and 1st reverse. The transmission has two power take-off shafts (A) and (B).

Worm and gear transmissions, consisting of two gearboxes - the upper gear and the lower worm gear - are usually used on light walk-behind tractors. The crankshaft of the engine has vertical arrangement. Sometimes machines with a gear-worm transmission are equipped with a centrifugal automatic clutch. Similar device walk-behind tractor provides increased compactness of the unit.

Belt-gear, belt-chain and belt-gear-chain transmissions are quite common in light and medium walk-behind tractors. The engine rotates the shaft of a gear or chain gearbox using a belt drive, which is also a clutch. Gear-chain transmissions are often implemented in one crankcase.

For a belt drive, to change the speed of the walk-behind tractor and take off power, the pulleys can have an additional stream. The advantages of such a transmission include a simpler disassembly and assembly of a walk-behind tractor than in the case of a gear transmission.

The figure below shows the V-belt transmission of the GreenField walk-behind tractor model MB-6.5 (with a belt-gear transmission), which, along with torque transmission and speed reduction, also performs the functions of a clutch and a gearbox (shifting speeds).

The clutch function is implemented using a tension roller and a control mechanism consisting of a link and a system of levers that allow you to change the position of the roller that tightens or loosens the belt and, accordingly, turns on or off the transmission of torque from the engine to the gearbox. Gear shifting is carried out with the help of two-strand pulleys. By rearranging the belt from one stream to another, they get a different speed of the walk-behind tractor.

A similar scheme is implemented in the domestic Salyut 5 walk-behind tractor, shown in the figure below. The V-belt transmission transmits rotation to the gear reducer of the walk-behind tractor.

As a rule, motoblock transmissions have PTO shafts, providing the transmission of torque to the working bodies of the machine. By their type and location in the transmission, power take-off shafts can be independent, located before the clutch and rotating regardless of its state (disengaged or engaged), or dependent, located after the clutch, and synchronous to a certain gear. In one walk-behind tractor there can be several power take-off shafts - different in type and speed of rotation.

Clutch

The clutch, which is part of the transmission, performs several functions. Transfer of torque from the engine crankshaft to the gearbox (gearbox) shaft, disconnection of the gearbox and engine during gear shifting, ensuring smooth starting of the walk-behind tractor and stopping it without turning off the engine.

Structurally, the clutch can be performed in different ways. In the form of a V-belt transmission (see above), the tension or loosening of the belt of which with the help of the clutch lever leads to the transfer or termination of the transmission of torque from the engine to the gearbox. Or in the form of a single-disk or multi-disk friction dry or wet (oil) clutch, which is more reliable and is used in most models of walk-behind tractors. Some machines use a much rarer conical clutch.

On the already considered walk-behind tractor "Ugra" LLC "Kadvi" a clutch is installed, which is the most traditional in its design - a friction multi-plate clutch with a pressure spring operating in an oil bath. The device of a walk-behind tractor with such a clutch should provide for the presence of a crankcase for the clutch, where gear oil is poured.

Ugra NMB-1 walk-behind tractor clutch scheme: 1 - Motor shaft, 2 - Drive half-coupling, 3 - Driven half-coupling assembly with release bearing, 4 - Belleville spring, 5 - Drive disks, 6 - Driven disks, 7 - Spring thrust ring.

Clutch lever: 1 - Axle, 2 - Fork, 3 - Clutch half, 4 - Lever, 5 - Clutch cable, 6 - Bolt, 7 - Nut, 8 - Washer, 9 - Spring washer, 10 - Sleeve.

The clutch consists of a driving half-coupling 2 (motoblock clutch scheme), a driven half-coupling 3, a belleville spring 4, leading 5 and driven 6 discs, a thrust ring 7. It works as follows. When the clutch lever is released, the Belleville spring compresses the driven and driving discs assembled in the package alternately. Due to the friction between the discs, torque is transferred from the engine to the gearbox. When the clutch lever is depressed, the force is transmitted via a cable to the clutch release lever 4 (Clutch lever). In this case, the clutch fork 2 compresses the spring through the driven half-coupling and release bearings, separating the driven discs from the leading ones and stopping the transmission of torque.

Differential

To improve maneuvering and smooth turns, the design of some walk-behind tractors (mainly heavy ones) provides for a differential. The purpose of the latter is to ensure the rotation of the left and right wheels at different speeds. Differentials can be with or without wheel locking. Instead of a differential, mechanisms can be used to turn off one wheel while driving.

Chassis

The chassis of the walk-behind tractor is a frame on which the main components and wheels are fixed. Sometimes the frame is missing, and its role is played by the transmission, to which the engine and wheels are attached.

In most walk-behind tractors, the distance between the wheels can be changed, this makes it possible to set the track of different widths. Two main types of wheels are used - conventional pneumatic and weighted metal wheels with wide lugs. Weights can be welded to the wheels or bolted to them. Many designs metal wheels provide for fastening loads of various weights. This allows, if necessary, to increase the weight of the walk-behind tractor to values that provide the necessary grip of the wheels with the ground.

Metal wheels can be with a solid rim or made in the form of two or three narrow hoops interconnected by lugs. The first ones have the disadvantage that the ground accumulates between the lugs, which prevents good adhesion of the wheels to the ground.

Governing bodies

The controls are a set of mechanisms that provide a change in the direction of movement and speed of the walk-behind tractor. These include: steering wheel, levers and gearshift rods, clutch control levers, supply of "gas", emergency stop of the engine, etc. Since the design of motoblocks, with very rare exceptions, does not provide for a seat for the operator, the motoblock device must ensure its control with one hand.

Some controls (carburetor air damper, power take-off, etc.) are located on the corresponding units and assemblies.

Usually on the left steering rod there is a clutch control lever and an emergency engine stop lever, on the right - the "gas" handle, the wheel drive lever and the brake (if any). The design of the steering column of walk-behind tractors provides, as a rule, for adjusting the position of the handles in horizontal and vertical planes. The figure shows the controls of the SunGarden MF360 walk-behind tractor.

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The clutch is an integral element of the transmission, the task of which is to transfer the torque received by the crankshaft to the gearbox and disconnect the gearbox from the engine when switching the speeds of the walk-behind tractor. It is thanks to the presence of this mechanism that the agricultural machine starts off smoothly and can stop without completely turning off the engine.

Clutch for walk-behind tractor - design and principle of operation

The clutch of absolutely any agricultural machine consists of a number of elements. The design of the mechanism includes:

Permanent control device;
host node;
driven components.

The design of the control mechanism includes a release lever connected to the pressure disc by means of a pedal release and rods. When the implement's clutch device is blocked, a signal is generated that the release levers receive. They, in turn, disconnect the driven disk from the pressure housing, as a result of which the mechanism is turned off.

The bearing in the clutch assembly of a modern walk-behind tractor serves to reduce friction, excluding, at the same time, the contact of the levers rotating around its axis and a completely motionless layer. For the return of control mechanisms in their out initial position spring responds. The layer, in this case, is repelled from the levers to the distance required for the final shutdown.

Types and description of motoblock clutch mechanisms

Depending on the design features of motoblocks, agricultural units can be equipped with the following types of clutch:

According to their type of friction, clutch mechanisms are divided into dry, as well as devices operating in air or in a bath of engine oil. Depending on the initial starting mode, a non-permanently open and permanently closed clutch is found on sale.

Do-it-yourself clutch for a walk-behind tractor

Regular operation of the clutch system implies constant friction of its parts, which is why even the most reliable mechanism sooner or later becomes unusable. After that, you can buy a new device, or try to make a homemade clutch for an agricultural machine.

Before you make a clutch on a walk-behind tractor, you will need to prepare certain parts. For work you will need:

Flywheel and input shaft taken from a gearbox from a Soviet Moskvich;
Swivel fist and serviceable hub from auto Tavria;
Driven pulley equipped with two handles;
Crankshaft from a GAZ-69 car;
B-profile.

First, grind down the used crankshaft so that it does not touch other internal elements of the device;
Next, put the regular hub of your walk-behind tractor on the shaft;
Machine a place in the surface of the shaft to install the bearing. As a result, the hub must be installed without the slightest gaps, and the pulley itself must rotate freely around its axis;
After that, turn the crankshaft over and do the above steps on its reverse side;
Then make 6 holes in the pulley using a drill with a 5mm bit. The holes must be evenly spaced. Keep in mind that 10mm bolts will be screwed into the holes, so you also need to drill holes on the back of the pulley;
Install the pulley over the flywheel, and fasten both parts with a bolt. Next, mark the places where you need to drill holes. Note that they must match the holes previously drilled in the pulley;
Pull out the pulley and drill small holes in the flywheel;
Machine the surface inside the flywheel and shaft so that the parts do not touch each other;
The mechanism should include a clutch handle on the walk-behind tractor. To make it, take a pipe, 30 long and about 10 mm in diameter, and fix it on a pulley;
The motoblock clutch cable can be taken from old chainsaw, or buy a new cord, and wind it on a reel.

A self-made clutch is suitable for installation on Agro, Neva MB-2 walk-behind tractors and agricultural vehicles of other brands.

The motoblock clutch is an important transmission element, through which the engine crankshaft transmits torque to the gearbox mechanisms. With the help of this part, during the gear change, the motor and gearbox are separated. It is due to the participation of the clutch that the walk-behind tractor smoothly moves off, and also stops without completely turning off the engine.

Clutch functions in the design of a walk-behind tractor

The operation of the clutch is based on the action of the friction clutch. This transmission element performs several important functions, among which stands out:

Uninterrupted torque transmission;
Suppression of torsion vibrations;
Smooth switching of speeds;
Impactless gear connection;
Connecting and disconnecting a gearbox with an internal combustion engine;
Disconnecting the transmission from the flywheel device.

The clutch device makes it possible to briefly turn off the crankshaft of the engine and the power transmission of the machine. Thanks to the clutch, the technique starts and stops the movement smoothly and without jerks.

Centrifugal clutch - device and advantages

This kind of element is worth highlighting among other designs due to its reliability and durability. It is used in checkpoints. automatic type. Its design consists of the following elements:

flywheel;
pulley;
Hubs with locking groove and key;
flange;
bushings;
casing;
bearing;
Retaining ring.

one of critical roles plays a differential device associated with a centrifugal clutch. It helps to improve the maneuverability of the equipment and ensure smooth movement in corners.

Together with the clutch, the differential regulates the rotation of the wheels of the walk-behind tractor for different speed. Moreover, the mechanisms that transmit power together act as wheel locks. In some models of equipment, instead of a differential, a special device is installed that blocks one of the wheels of the walk-behind tractor at the command of the driver.

More modern models vehicles are equipped with a friction clutch. It is mounted between the motor and gearbox. In this design, the driven parts are closely connected with the input shaft of the gearbox, and the leading parts are connected with the crankshaft of the motor. In most cases, both driving and driven elements are made in the form of flat round discs, or in the form of a cone. Just like centrifugal, friction clutch is put into operation by manipulating a separate handle.

The principle of operation of the clutch

The clutch for a walk-behind tractor consists of several important elements:

control devices;
leading element;
driven details.

The leading part consists of the front side of the engine flywheel and the pressure plate. The disc rotates with the attached flywheel. At the same time, the disk can also move along the axis with respect to the flywheel. Between these two elements is a driven disk, which is located on the driven shaft. Along the perimeter of the pressure plate are spring elements in the form of cylinders.
The function of the springs is based on the compression of the disk they support.

In this case, the other end of the springs is in contact with the casing. Thus, the springs maintain the clutch for the walk-behind tractor in a constant on state.

The control mechanism is made of release levers connected to the pressure plate housing by means of pull rods and a pedal. By disengaging the clutch, the owner of the walk-behind tractor engages the clutch cable, which transfers force to the release levers. When the springs are compressed, the levers move the driven disk away from the pressure one, which leads to the disengagement of the clutch.

The bearing reduces friction by preventing the fixed taper from touching the rotation levers. Most models of walk-behind tractors are equipped with three levers located at an angle of 120 degrees with respect to each other. With the help of a spring, each clutch lever returns to its original position. In this case, the layering moves to the distance necessary to turn off the levers. If this distance is not reached, then the clutch begins to slip.

How to make a clutch mechanism with your own hands?

The clutch on the walk-behind tractor works on the principle of increased friction of the components, so rapid wear cannot be avoided. In this case, you should try to make the mechanism with your own hands. The design of a homemade clutch will be composed of:

the input shaft of the gearbox and the flywheel of the Moskvich car;
hub and knuckle from Tavria;
B-profile;
Two stream driven pulley;
Crankshaft from GAZ-69.

Subsequent work on the assembly of the mechanism is as follows:

1. First you need to grind off the crankshaft so that it does not cling to other elements of the walk-behind tractor;
2. We put the regular hub of the walk-behind tractor on the shaft;
3. Next, on the shaft, it is necessary to machine a place for the bearing. This operation should be carried out as precisely as possible so that the bearing fits perfectly on the shaft. As a result, the hub should fit without any gaps, and the pulley should scroll;
4. Then turn the crankshaft over and do the same on its reverse side;
5. Next, with a drill with a 5 mm drill, make 6 holes in the pulley. The distance between them must be the same. Since 10mm bolts will be used, reverse side the wheel that drives the drive belt also needs to be drilled;

Next, install the pulley on the flywheel, and tighten both parts with a bolt. After that, mark the drilling locations on the flywheel so that they coincide with the 6 holes in the pulley;
Remove the pulley and drill holes in the flywheel;
After that, put the pulley back on and securely tighten the structure with bolts;
Machine the inner surface of the crankshaft and flywheel so that they do not beat against each other.

The finished structure can be installed in a regular place in the walk-behind tractor. Do not forget to connect the cables, leading them as far as possible from the friction elements.