How the clutch works on a tiller


Clutches are constantly being improved, like other components and systems of cars. over, each type has both advantages and disadvantages. The main thing is to have an idea of ​​the type of clutch that is installed on your car and operate it correctly.

How the clutch works on a motorcycle


Transmission. Clutch and quickshifter

Text: Artem ‘S1LvER’ Terekhov

Any motorcycle must be able to disconnect the crankshaft drive from the rear wheel so that the engine can run when the bike is stationary. Despite this obvious statement, imagine this possibility did not always exist.

Many early motorcycles used direct drive with a belt and pulleys on the crankshaft and rear wheel that could not be separated. Such a drive really worked, but some problems got out during its operation. For example, to stop at an intersection, you had to turn off the engine. And in this case it was possible to start the bike only from the “pusher”, which is clearly not the best starting option. The clutch mechanism has been designed to ensure that the running engine is decoupled from the rear wheel drive. The second function is no less important. the ability to select gear ratios on machines that are equipped with a gearbox. Let’s see how this mechanism works.

Clutch work is based on friction. In its simplest form, the clutch consists of two discs, one of which is located on the crankshaft journal, and the second is connected through some drive mechanism (chain, belt, gears) to the rear wheel and pressed against the first disc. If there is a small gap between the discs, the engine is running, while the second disc remains stationary. If you connect the discs to each other, then the rotation of the crankshaft due to friction will be transferred to the second disc, and since it is connected to the rear wheel, it will also rotate. So the power supply from the engine to the wheel can be switched on or off as needed. The vast majority of modern production bikes use a hand-operated lever clutch on the handlebars. The exception is scooters that use an automatic centrifugal clutch, the operating mode of which depends on the engine speed. In our article, we will focus specifically on the clutch used on motorcycles (unfortunately, the format of the article does not allow us to laugh enough at funny stories about scooters who have switched to motorcycles and try to “brake” the clutch).

How the clutch works

The entire clutch assembly is installed on the input shaft of the gearbox (read about the device of this device in our article). The clutch housing or outer drum is mounted on a bearing and can rotate freely and independently of the shaft. The outer clutch drum is directly connected through the forward gear to the crankshaft (although there are some designs in which the clutch is mounted directly on the crankshaft journal; this scheme is common on BMW and Moto Guzzi motorcycles), so that when the crankshaft rotates, it also rotates. The central part of the clutch, or inner drum (hub), is smaller and is located inside the outer drum. It is installed on the input shaft of the gearbox and is fixed on it against turning by splines, so that when the inner drum rotates, the input shaft also rotates.

Wet multi-plate clutch section, Yamaha R6 2008

The clutch plates are located between the outer and inner drums. Two types of discs are used: smooth and friction discs. They are positioned alternately, and the exact number of discs depends on the type of clutch and the machine on which it is used. On the outer circumference of the friction discs there are rectangular splines, which are installed in the grooves of the outer clutch drum. Teeth are cut on the inner circumference of smooth discs, which are installed in the grooves of the inner clutch drum.

In the normal position (when the bike is in motion) the friction and smooth discs are held in direct contact by springs acting on a plate called the pressure plate. When the crankshaft and the outer clutch drum rotate due to friction between the plates, the inner clutch drum, and therefore the input shaft of the gearbox, also rotate.

When the rider squeezes the clutch lever, the cable or hydraulic mechanism, counteracting the force of the springs, pushes the pressure plate away from the package of smooth and friction discs, as a result of which the discs stop contacting. By eliminating direct contact between the discs, friction is reduced, allowing the outer drum to rotate freely relative to the inner drum. As the rider releases the clutch lever, the discs are pressed against each other again, and gradually rotation of the outer clutch drum is transferred by friction to the inner drum, thus gradually transferring torque to the gearbox and beyond. to the rear wheel; thanks to this, the possibility of stopping or jerking is excluded (of course, if everything is done correctly and the clutch is released smoothly).

clutch, works, tiller

How to Slip the Slip Clutch on a Rototiller (or Brush Hog, etc.)

The ability of a clutch to transmit torque depends on many factors: the number and diameter of the discs, the force of the springs compressing them, and the coefficient of friction between the discs. All other things being equal, smaller machines require fewer disks than larger and more powerful machines. Similarly, if the torque is the same, then with an increase in the diameter of the discs, their number can be reduced. Friction discs (who would have thought?) Are coated with friction material, and smooth discs are made of steel.

2007 Honda CBR1000RR Clutch Components

Design Matters When choosing the type of clutch to install on a particular motorcycle, the designer’s decision is influenced by several determining factors. First, let’s look at the number of disks. A multi-plate clutch uses more than one set of smooth and friction discs, usually seven or eight or sometimes nine friction discs. There are always one less smooth discs than friction discs, since the disc pack is always limited on both sides by friction discs. Most monoblock engines (that is, those in which all transmission units are made within the engine crankcase) with a transverse crankshaft in the frame use a multi-plate clutch. The reason for this is the small diameter of the clutch. A multi-plate clutch is also much lighter than a single-plate clutch, although it has a larger friction surface and strength. Single or double disc clutches are used on motorcycles with a longitudinal crankshaft in the frame (for example, Moto Guzzi bikes with a V-twin, the cylinders of which are located across the frame). The clutch is mounted on the rear crankshaft trunnion and has a separate housing between the engine and gearbox. Due to this arrangement, the clutch does not require compactness, and with a large diameter, only one or two discs are needed.

The next question that designers decide is whether to use a dry clutch or an oil bath clutch.

Ducati 749 dry clutch exposed (in stock, of course, covered with a cover)

clutch, works, tiller

You can’t go against physics. it is natural that the friction provided between the clutch discs operating in an oil bath is lower than the friction between the dry clutch discs. Therefore, discs of large diameter or a greater number of them (or maybe both) are needed, which leads to an increase in size.

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Suzuki RGV250 equipped with dry clutch Same as RGV250 but with wet clutch

This is why dry clutch is primarily used on sport bikes. High efficiency and low weight (no need to pour oil) is an integral part of a dry clutch. However, the same as a small resource. Most racing machines are equipped with a dry clutch, as are almost all Ducati civilian sportbikes (except the 848, but there is a separate factory “dry kit” for it). Japanese manufacturers mainly use an oil bath clutch. From a practical point of view, a “wet” clutch looks preferable. a much longer service life and less tendency to overheat. On the other hand, if the goal is maximum performance in a race, then dry grip will be chosen.

Nothing is broken here, this chatter is the sound of a working Ducati dry clutch

Another point with which the designer must decide is how the force will be transferred from the lever to the clutch drive mechanism. Most often, a cable is selected for this purpose, otherwise a mechanical clutch drive. Ropes are susceptible to pulling and wear, they need to be adjusted and lubricated, but they are easy to maintain and repair. The mechanical drive is simple. the cable acts on the clutch by means of a drive mechanism located inside the clutch cover or on the opposite side of the crankcase, while the mechanism acts on a long pusher passing through the input shaft of the gearbox.

The hydraulic clutch actuator is mainly used on large machines. It costs much more and requires careful maintenance, but the disadvantages are more than offset by the smoothness and ease of its operation.

The hydraulic drive works on the same principle as the front brake system (we will also talk about brake systems in due time): when the lever presses on the plunger of the master cylinder, it acts on the hydraulic fluid and pumps it into the hose. Then the fluid pushes the piston of the working cylinder, which acts on the pusher located inside the input shaft. Except for regularly checking the fluid level, the hydraulic system is virtually maintenance-free, although the fluid and seals need to be replaced periodically to ensure proper operation. Also, the design of any hydraulic system implies that the fluid is prone to water absorption and air saturation (in a word, servicing the clutch hydraulic drive is similar in thoroughness to servicing the brake system). With that out of the way, let’s move on to more modern and high-tech stuff. I think when reading reviews of modern motorcycles, you have repeatedly come across the phrase “slippery clutch”. As a rule, the presence of it on the tested motorcycle delights the tester, which he immediately reports. However, no one really explains how this thing works. Let’s start with this.

The clutch slip mechanism (hereinafter referred to as PS for simplicity) is a development focused on high-performance motorcycles. The main goal for the PS is to limit the reverse torque that occurs when the engine is braking from high speed or when downshifting. For the first time, the PS was used on a 70s drag bike under the name Hogslayer. a non-trivial clutch for that time allowed the Svinoboy to accelerate to 290 km / h without skidding or overheating (in addition, this maximum speed was facilitated by two 880-cc injection engines from Norton, but that’s a completely different story.).

Among modern mass-produced motorcycles, the slipper clutch has also found its place. mainly, it is equipped with sports bikes, as well as charged factory streets.

Slipper clutch for Ducati 999 from FBF

Now more about why the PS is used at all. When throttle is opened, the rear wheel is driven through the clutch. When the throttle is closed and the bike continues to move at a speed greater than a predetermined limit corresponding to the current throttle opening, the rear wheel still rotates the engine shaft through the clutch; but because the engine has a lot of resistance (due to compression, especially at high rpm and low gears), it is possible to reach a point where the resistance, or reverse torque of the engine, exceeds the grip coefficient of the rear tire. The result is a locked rear wheel. Such an outcome is especially likely in rainy conditions, because In the rain, the tire’s grip is greatly reduced, and the weight redistribution that occurs during heavy braking reduces the load on the rear axle. PS is installed in order to exclude the possibility of locking the wheels due to slipping of the clutch when changing the direction of the transmission of torque. However, the PS does not completely disengage the clutch and the engine braking effect remains.

Different manufacturers approach the PS design in different ways, but most often slippage is provided by the following mechanism: the inner clutch drum is located on a number of ratchet stops with an inclined surface. When the direction of transmission of torque is changed, the inner clutch drum shifts on the ratchet stops, thereby deflecting the pressure plate and relieving pressure on the discs. This approach was first tested in series on the Kawasaki ZXR 750.

2007 Kawasaki ZX-6R slip clutch as standard

The Aprilia engineers took a more sophisticated and technological path when designing the RSV Mille clutch. To move the inner clutch drum, a servo motor is used, which is controlled by a vacuum supplied from the engine intake manifold. When the throttle is closed, the increased manifold vacuum creates a vacuum in the air line of the servo motor, which moves the inner clutch drum and relieves pressure on the discs. This approach is no longer used anywhere other than the RSV, manufacturers prefer the simpler version tested on the ZXR 750 (each company tries to bring something different to the PS design, but the general principle remains very similar to the version from Kawasaki). Whatever one may say, despite its simplicity, the slipping mechanism in the clutch is a very, very useful thing. If your motorcycle is not equipped with PS. do not despair, it is likely that a tuning kit for it exists in nature, you just need to look.

Finally, we got to the long-awaited topic. Translogic quickshifter systems, it is. BMW Quickshifter. Contrary to the sensational claims of the German company about the new super-technology, similar systems of “fast gear shifting without releasing the clutch by the rider” are produced by some tuning firms, the most famous of which are. Translogic and Dynojet have long been used by World Superbike, Supermoto / MX and even karting champions. It’s just that BMW was the first company to use this system in some production bikes.

The advantage of the mechanism lies in its very name: “quick”. “fast”, “shift”. “shift, shift, switch”. That is, “quickshifter” literally translates to “quick switch”. How quickly the gear changes, you ask. The answer can be found in the example that is given on the official Translogic page. “For the most professional motorcycle racer, gear changes take at least 340 milliseconds, while for systems from Translogic it takes between 48 and 150 milliseconds.” Impressive, isn’t it? Another technology that descended from the Olympus of big motorsport and became available to “mere mortal” motorcyclists.

DynoJet QuickShifter Kit

Now let’s deal with the quick-clutch device. The key elements of the entire mechanism: a pressure sensor (monitors the pressure on the gearshift foot; simply speaking, it determines whether the rider presses on it or not) and the quickshifter thrust (if the standard one does not fit). Some manufacturers (for example, Dynojet) also offer a quickshifter on / off button that can be installed on the steering wheel. The sensor is connected to an external ignition control module (for example, Power Commander). When the rider puts pressure on the shift pad, the sensor sends a signal to the ignition control module, after which it gives the ECU a command to temporarily turn off the ignition (for several tens of milliseconds). When the engine is off, a changeover occurs. without throttle release and clutch release. In the case of BMW motorcycles, you do not need to buy an ignition control unit. the quickshifter is connected to native “brains”, you do not need to adjust or install anything. Usually the quickshifter is installed when they want to improve the accelerating dynamics of the device, but nothing prevents you from switching down in the same way when braking.

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Hopefully, as you read this article, you have made some more progress in your understanding of what a motorcycle is. However, many iron questions have not yet been solved, so stay with us, there are many interesting topics for discussion ahead.!

How the clutch works on a motorcycle?

With the bike in neutral, the rider “squeezes” the clutch and presses the gearshift lever. This causes the select mechanism to engage first gear by sliding the fork to which the corresponding coupling mechanism is connected.

Releasing the clutch transfers torque from the engine through the transmission to the rear wheel.

As the speed rises, the rider releases the throttle, squeezes the clutch and lifts the gearshift lever up.

The select mechanism shifts the first gear mechanism to neutral and then closes the second gear mechanism. The clutch is released, the throttle opens and the acceleration continues.

A similar mechanism works with each subsequent switch “up” and in the opposite order when switching “down”.

How the clutch works in a manual transmission car?

Clutch. The manual transmission is paired with a clutch. Thanks to this unit, it is possible to temporarily disconnect the motor from the transmission, which allows painless gear shifting (steps) without turning off the engine speed.

The clutch unit is necessary because significant torque passes through the manual transmission. Any conventional transmission design has parallel shaft axes on which the gears are based. The common body is called the crankcase. The most popular are three-shaft and two-shaft companies.

The three-shaft has three shafts:

  • The first is the leader;
  • The second is intermediate;
  • The third is a slave;

The first shaft is connected to the clutch; splines are cut on its surface along which the clutch driven disc moves. From this axis, rotation is transmitted to the intermediate axis, rigidly connected to the gear of the input shaft.

The driven shaft of the manual transmission has a specific location. It is coaxial with the leading one and connected to it through a bearing located inside the first shaft. This, in turn, allows for their independent rotation.

The gear blocks from the driven axle do not have a rigid fixation with it, and the gears are delimited by special synchronizer couplings. The latter just sit rigidly on the driven shaft, but are able to move along the axis along the splines.

The ends of the couplings have toothed rims capable of connecting with the same rims located at the ends of the gears of the driven shaft. The modern gearbox design assumes the presence of such synchronizers in all forward gears.

When shifting the gear into neutral mode, the gears rotate freely, and the position of all synchronizer couplings is open. When the driver squeezes the clutch and switches the lever to one of the steps, then at this time the fork in the gearbox moves the clutch into engagement with its pair at the end of the gear. So the gear is rigidly fixed with the shaft and does not scroll on it, but provides the transfer of rotation and force.

From the driven shaft, torque and revolutions are transmitted to the drive wheels through the propeller shaft (on the rear wheel drive) or through the gearbox and CV joints (on the front wheel drive). When the synchronizer directly engages the drive and driven shafts without the participation of gears, the gearbox provides maximum efficiency. For reverse speed, an intermediate “parasitic” gear is installed, which reverses rotation.

Synchronizers. Modern manual transmissions have synchronizers. Without them, in order for the peripheral speeds of the gears to equalize, and to ensure the possibility of switching stages, drivers would have to do double squeezing.

But it should also be noted that on gearboxes with a large number of gears (sometimes up to 18 steps), synchronizers are not installed, which is typical for special equipment. It’s just technically impossible.

The synchronizer works as follows. When the driver engages the gear, the clutch moves towards the desired gear. During movement, the force is transferred to one of the locking rings of the clutch. Due to the different speeds between the gear and the clutch, the tapered surfaces of the teeth interact with the help of frictional force. She turns the locking ring on the stop.

clutch, works, tiller

The teeth of the latter are set against the teeth of the clutch, so subsequent displacement of the clutch becomes impossible. The clutch comes into engagement with a small rim on the gear wheel without any resistance. Due to this connection, the gear is rigidly locked with the clutch. This process takes place in a fraction of a second. One synchronizer usually provides two gears.

Gear shifting process. The corresponding mechanism is responsible for shifting gears. On rear wheel drive vehicles, the lever is mounted directly on the manual transmission housing. The whole mechanism is hidden inside the body of the unit, and the shift knob directly controls it.

Front wheel drive vehicles can be equipped with a shift lever in the following locations:

  • floor between the driver’s and front passenger seats;
  • on the steering column;
  • in the area of ​​the instrument panel;

Remote control of the gearbox for front-wheel drive cars is carried out using rods or rockers. This design also has its own characteristics.

Replacing clutch discs on a motorcycle

If all steps were done correctly, then there should be no problems.

What is a motorcycle clutch?

How the clutch works?

The clutch is one of the most important structural components of a car’s transmission. It performs a short-term disconnection of the power unit from the transmission and their smooth connection with each other during gear changes. This structural element is located between the gearbox and the engine.

1 General

The clutch is based on the action of the friction clutch (sliding frictional force). This transmission component is intended for:

  • transmission of torque;
  • damping torsional vibrations;
  • smooth gear shifting;
  • shockless gear connection;
  • connection and short-term disconnection of the connection of the internal combustion engine with the checkpoint;
  • disconnecting the transmission from the flywheel.

The mechanism makes it possible to temporarily disconnect the power transmission of the tiller and the crankshaft of the motor. In addition, the tiller with the help of the clutch without jerking starts the action. Being of great importance for agricultural machines when driving, the clutch allows you to get under way (although it is possible to do this without it, it is very difficult).

The centrifugal clutch has proven itself as a reliable component of the transmission. It has found its application in automatic transmissions. Its main working elements include: a flywheel, a pulley, a hub with a key and a locking groove, a flange, a casing, a bushing, a bearing, a circlip.

The differential, which is directly related to the clutch, also plays an important role. It is tasked with improving the maneuverability of heavy class trailers and ensuring smooth turning. The clutch and differential in “symbiosis” regulate the rotation of the wheel part of the tiller at different speeds. In addition, the power transmission mechanisms are equipped with wheel locking functions. However, in some models, the differential is replaced by a special device that disables one wheel when driving.

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On modern models, the tiller usually uses a friction clutch. It is installed between the gearbox and the engine. With a friction clutch, the driven elements are closely connected with the input shaft of the gearbox (or another transmission unit following the clutch), and the leading elements are closely connected with the engine crankshaft. As a rule, the leading and driven elements are made in the form of round flat discs, sometimes they are made in a conical variation (for example, Tilleri BChS-735 and Kataisi Super-600) and block (Gutbrod, Mepol-Terra).

In the case of the production of these working bodies in the form of V-belt drive pulleys, tension rollers are additionally introduced, allowing you to set their position, the degree of tension from the belt control rod, and disconnect and connect the engine to the transmission.
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2 Types of clutch, their features

Depending on the design characteristics of motor vehicles, the clutch for the tiller can be of such types as:

  • frictional (discussed above);
  • electromagnetic;
  • hydraulic;
  • centrifugal;
  • belt;
  • one-. two-disk;
  • multi-disc.

By the type of friction, the considered mechanism is classified into wet, operating in an oil bath, and dry, operating in an air environment. In accordance with the mode of inclusion, a permanent closed and non-permanently closed clutch are distinguished.

Centrifugal works due to the following working elements: clutch cable, transmission input shaft, flywheel, clutch lever, release bearing, handle, driven disc, engagement lever, stem fungus, lock washer, shutdown fork. Centrifugal devices have not found widespread use due to their tendency to slip, which is characteristic under loads, and wear of friction surfaces.

With a hydraulic system, through the connecting rod, when the pedal is depressed, the movement is transmitted to the piston, pushing the hydraulic fluid through a special channel. The piston, under the action of the pressure of the working medium, acts on the lever through the connecting rod. With a spring, it returns to its original position.

The multi-disc and single-disc operating principles practically do not differ from each other. The advantages of the first are based on the small size of the friction discs, smooth engagement of the clutch. The disadvantages are worse cooling conditions, problems in obtaining the purity of the inclusion. Two-disc mechanisms are installed in connection with the high power of the power unit, the need to transmit increased torque, to increase the service life.

Homemade Tiller Clutch

The belt-driven clutch, which provides the transmission of torque from the motor to the gearbox, is considered one of the first and is inferior to the above mechanisms, because has a number of disadvantages: a high level of wear, unreliability, low efficiency, impracticality when working with powerful engines.
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Tiller clutch: types, device, principle of operation

As an integral part of the transmission, the tiller clutch performs the function of transferring torque from the motor crankshaft to the gearbox (gearbox shaft). With its help, during gear shifting, the power plant and the gearbox are disconnected. Due to this mechanism, the tiller or motorboat starts to move and stops without turning off the motor.

If the conceived design of factory-made motor vehicles does not provide for the implementation of the clutch, it can be assembled independently.

1.1 Design and principle of operation

The friction-type clutch consists of:

  • control mechanism;
  • leading part;
  • driven elements.

Centrifugal clutch to tiller

The drive end is formed from the end face of the motor flywheel and the pressure plate, which rotates with the flywheel. However, the disc has the ability to move in the axial direction relative to the flywheel. Between them is the driven disc, its hub is located on the splined driven shaft. Coil springs are placed around the circumference of the pressure plate, installed with preliminary compression.

The role of the springs is to press the pressure disk, into which they abut with one end, and the other against the casing, together with the driven end surface of the flywheel. As a result of these actions, the clutch arrives constantly in the engaged state.

The control mechanism includes release levers, which are connected to the pressure plate by rods and a branch with a pedal. When disengaging the clutch, the operator sends a force from the pedal or lever using a fork or cable to the release levers through a release bearing with a release bearing. With their outer end bolted to the pressure plate, the levers during the compression of the springs move the driven discs away from the pressure plate, thereby disengaging the clutch.

The bearing reduces friction by eliminating contact between the stationary arm and rotating arms. Usually there are three levers in the configuration, placed at an angle of 120 degrees to each other. By means of a spring, the parts of the control mechanism are returned to their original position. The branch is separated by the amount of clearance from the levers required to completely disengage the clutch. If this distance is not observed, the clutch slips and the friction linings wear out. When the clearance exceeds the required distance, the clutch will not completely disengage.
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2.1 Retrofitting the clutch

Since the principle of operation of the device provides for serious friction of the component parts, natural wear cannot be avoided. You can make a clutch on a tiller with your own hands, however, owners of motorized cars who do not have experience in plumbing are not recommended to perform this operation.

Let’s consider an example of creating a mechanism for a heavy tiller. The basis is the flywheel and the input shaft of the Moskvich car box, a steering knuckle with a hub from Tavria, profile B, a driven pulley for two strands and a steel billet as a crankshaft (suitable from GAZ-69). The self-made product begins with turning a steel billet on a lathe in order to fit a hub onto the resulting false shaft. After the pulley lands on the sharpened shaft, you should grind the seat in diameter on the inner ring of the pulley under the support bearing, which should “sit” perfectly.

If the hub fits without gaps, and the pulley scrolls, this is a sign of a correctly completed task. Turn the part over and do the same on the back side. In the next step, use a drill and drill (5 mm) in the pulley to make 6 holes equidistant from each other. Since the bolts will be 10 mm, on the back side it is necessary to drill out the holes of the wheel that gives movement to the drive belt with a 12 mm drill.

Crankshaft Crosser CR-M12

A pulley is installed on the flywheel, a hole should be made with the same drill and both parts should be tightened with a bolt to fix. While the pulley is on the flywheel, mark the flywheel through the holes you made earlier. Remove your pulley and drill all 6 holes.

Use bolts (10 mm) to tighten the structure, the thread without head should be 60 mm. Grind the crankshaft inside with a blank. To prevent the flywheel from hitting, it is also necessary to grind its surface, and then center it along the landing hole.

It may be necessary to slightly trim the inner plane of the flywheel together with the pulley on a lathe. The metal layer is removed no more than 1 m. Having previously seated the flywheel on the shipment, check the runout of the planes, it should not exceed 0.1 mm. Ultimately, it remains to mount the basket on the flywheel.
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