The choice of the required camshaft should begin with two important decisions:
First, let's check how we determine the operating rpm range, and how the choice of camshaft is determined by this choice. Maximum engine speeds are usually easy to isolate, as they directly affect reliability, particularly when the main parts of the block are conventional.
Maximum engine speed and reliability for most engines
| Maximum engine speed | Estimated working conditions | Expected service life with related parts |
| 4500/5000 | Normal movement | Over 160,000 km |
| 5500/6000 | "Soft" forcing | Over 160,000 km |
| 6000/6500 | Approximately 120,000-160,000 km | |
| 6200/7000 | Forcing for everyday driving/ "soft" racing | About 80,000 km |
| 6500/7500 | Very "hard" street riding or "soft" to "hard" racing | Less than 80,000 km in street driving |
| 7000/8000 | Only "hard" races | Approximately 50-100 runs |
Keep in mind that these recommendations are general. One engine can hold up much better than another in any category. How often the engine is accelerated to maximum speed is also very important. However, as general rule you need to be guided by the following: the maximum engine speed should be below 6500 rpm if you are building a boosted engine for everyday driving, and it is required reliable performance. These engine speeds are normal for most part limits and can be obtained with medium force valve springs. So if reliability is the primary goal, then a top speed of 6000/6500 rpm would be a practical limit. Although the decision on the maximum RPM required may be relative simple process based in principle on reliability (and maybe cost), the inexperienced engine designer may find determining the engine's operating speed range a much more difficult and dangerous task. Valve lift, stroke duration and cam profile camshaft will determine the powerband, and some inexperienced mechanics may be tempted to choose the "largest" possible camshaft in an attempt to increase the engine's maximum power. However, it is important to know that maximum power only needed for a short time when the engine is at full speed. The power required from most uprated engines is far below the maximum power and RPM; in fact, a typical boosted engine can "see" a full opening throttle valve only a few minutes or seconds for a whole day of work. However, some inexperienced engine builders ignore this obvious fact and choose camshafts more by intuition than by guidance? If you suppress your desires and make a careful choice based on real facts and possibilities, then you can create an engine capable of delivering impressive power. Always keep in mind that the camshaft is pretty much a compromise part. After a certain point, all the gains come at the cost of low-end power, loss of throttle response, economy, etc. If your goal is to increase the number Horse power, then first make modifications that add maximum power by improving intake efficiency, as these changes have less of an effect on power at low rpm. For example, optimize the flow in the cylinder head and in the exhaust system, reduce the flow resistance in the intake manifold and in the carburetor, then install a camshaft in addition to all the above "set". If you use these techniques judiciously, the engine will produce the wider power curve possible for your investment of time and money.
In conclusion - if you have a car with automatic transmission, then you need to be conservative when choosing the valve timing of your camshaft. Too long valve opening will limit engine power and torque at low rpm, which are essential elements in ensuring good acceleration and starting the car from a standstill. If your car's torque converter stops at 1500 rpm (typical for many standard transmissions), then a camshaft that puts out good torque, though not necessarily maximum power, at 1500 rpm will provide good acceleration. You may be tempted to use a high stop torque converter and long valve timing in an attempt to achieve best result. However, if you are using one of these torque converters with normal traffic then their efficiency at low speeds will be very low. Fuel efficiency will suffer quite a lot. For an everyday car, there are more efficient ways to improve acceleration with low speed.
Let's summarize the main elements of choosing a camshaft. First, for everyday driving, the maximum engine speed must be maintained at a level not exceeding 6500 rpm. RPMs above this limit will noticeably shorten the life of the engine and increase the cost of parts. While a "normal" engine can benefit from as much valve lift as possible, too much valve lift will reduce engine reliability. For all high lift camshafts, bronze valve guides are a necessary item to ensure long term bushing service life, but for valve lifts of 14.0 mm or more, even bronze guide bushings cannot reduce wear to a level acceptable for normal applications.
The longer the valves are held open, especially inlet valve, the more maximum power the engine will produce. However, due to the variable nature of camshaft timing, if valve timing or valve overlap goes beyond a certain point, all the extra maximum power will come at the cost of low-end performance. Camshafts with intake strokes up to 2700 measured at zero valve lift are good replacements for standard camshafts. For high-powered engines, the upper limit of the duration of the intake stroke of more than 2950 is the property of a purely racing engine.
Valve overlap causes some torque loss at low rpm, however, these losses are reduced when valve overlap is carefully selected for the application - from about 400 for camshafts standard engines up to 750 or more for special applications.
Valve timing, valve overlap, valve timing and cam center angles are all related. It is not possible to adjust each of these characteristics independently on single cam engines.
Fortunately, most camshaft specialists have spent many years creating cam profiles for power and reliability, so they can offer a camshaft that suits your needs well. However, do not blindly accept what the masters offer you; you now have the information you need to competently discuss camshaft specifications with camshaft manufacturers.
After all, the camshaft is one of the parts of the intake system. It must match with the cylinder head, intake manifold and exhaust system. Volume intake manifold and the size of the exhaust manifold pipes must be matched to match the power curve of the engine. In addition to this, the air flow rate in the carburetor, the number of chambers, the type of activation of the secondary chamber, etc. also have a noticeable effect on power.
Previously, when automatic washing machines were just coming into use, spinning clothes in them especially pleased the owners. It's no joke - technology freed them from such a tedious process. Then no one thought about the frequency with which the drum rotates. The machine still squeezed much better than a man. Now manufacturers are trying to make sure that the wrung out in washing machine linen could almost immediately hang in the closet. True, increasing the speed of rotation of the drum - the method by which they are trying to achieve this, in our opinion is very doubtful. Let's try to figure out if the washing machine needs "space" speeds?
Spin in the washing machine: observe speed mode!
The final stage of washing spinning has always been one of its most difficult stages. As the saying goes, "the last fight is the hardest." Women, who in our country, as a rule, were engaged in washing, it was at this stage that they called for help from their husbands and children: one cannot wring out a heavy duvet cover.
Fortunately, times have changed. Now, in fact, none of the family members is engaged in laundry in the house. Preparing and sorting laundry does not count. The process itself is at the mercy of automation a modern washing machine has settled in our apartments.
You can talk for a long time about what programs and functions have washing machines of various price categories and manufacturers, how they differ from each other or vice versa similar. Sometimes, on specialized Internet forums or even just in the subway, there are disputes about which programs a washing machine needs, and which ones you can do without. All disputants, however, agree on one thing without spinning, an automatic washing machine would immediately lose its attractiveness.
Classes and spin technology
Washing machines according to the spin class are divided into 7 categories, which are indicated by Latin letters A, B, C, D, E, F, G. The award of one category or another depends on the residual moisture content of the laundry, which is measured as a percentage. It is determined simply dry laundry is weighed before washing, and after it the wrung out (wet) is weighed. The dry weight is subtracted from the wet weight, and the resulting difference is divided again by the dry weight. The quotient is multiplied by 100 percent the desired result is obtained.
The residual moisture content of the laundry in spin class A should not exceed 45 percent. The B-class allows residual humidity up to 54 percent, C up to 63, and D up to 72. Models that wring out worse are now practically not found on sale.
I must also say that you should not be "scared" by washing machines whose spin class is lower than A (there are, by the way, the majority) the difference between classes A and B or even C although it looks significant as a percentage, in practice it is not so great. Of course, when spinning the C-class, it will take a little more time to dry the laundry, but the quality of the wash (what a washing machine is actually needed for) will obviously not get worse.
But the spin class depends not only on the degree of residual moisture content of the laundry. One of its criteria is also the number of revolutions that the drum of the washing machine can make in a minute. The more of them, the higher the chances of the manufacturer to proudly announce that the spin class of their unit is A. In most models on the market today, the number of revolutions is 1000 1200 per minute. However, there are units that "accelerate" to 1600, 1800 and even 2000 rpm (for example, the Gorenje WA 65205 model).
Is it good or bad? Do you need such "cosmic" spin speeds or will the usual, "earthly" ones be enough? To answer these questions, it is necessary, first, to understand how the spinning process actually takes place.
Basically, it's not complicated at all. After rinsing is completed, the used water is drained using a pump. Then the spin itself begins. The number of revolutions of the drum gradually increases, the water from the laundry, obeying centrifugal force, through the holes in the drum enters the tank, while the pump periodically turns on and it is removed into the sewer. The engine (and hence the drum) reaches its maximum speed at the end of the spin cycle, and only for a few minutes (usually no more than two).
Expert opinion
Returning to the question of the need for "high speeds" of rotation of the drum, it should be noted that until recently in Russia there was a strong opinion that what more revs per minute during the spin cycle is able to make the drum of the washing machine, the better and more reliable the entire unit as a whole. Actually it is not. In order not to be unfounded, we decided to turn to practitioners specialists of one of the largest Moscow household appliance repair networks A-Iceberg. Our questions were answered by Andrey Belyaev, manager of the large household appliances repair department, whose work experience in this area is 11 years.
-Andrey Viktorovich, can it be argued that the number of revolutions of the washing machine drum during the spin cycle is indirectly an indicator technical excellence, greater reliability of the model, and hence more long term her services?
No, there is no direct relationship between the number of revolutions of the drum, the service life and reliability of the machine. Each model has its own service life set by the manufacturer, and he also takes responsibility for warranty service of its equipment, produces spare parts. And even machines with 400 600 drum revolutions per minute (now these are usually narrow and compact models) may well operate for more than ten years. True, the service life, which is announced by the manufacturer, is also subject to revision. For example, at Ariston, the service life of machines has decreased from 10 years to 7. At the same time, the manufacturer did not provide any official explanations. But many experts believe that this is due to an increase in the number of complaints about the operation of units of this brand, and in fact this indicates a decrease in product quality and a “safety net” for the manufacturer. It should be noted that a similar trend (decrease in quality) is now observed in many firms producing household appliances. This can be explained by the desire of some companies to reduce the cost of their products, to make them available to a wide range of customers. Because of this, many resort to purchasing cheaper components as a result, quality suffers.
But don’t they put, for example, reinforced bearings and other specially prepared components on units with a high number of drum revolutions?
They put it, but, alas, this does not lead to a serious increase in the working life of the same bearings. In principle, even the opposite can be argued - the lower the number of revolutions, the longer some components of the washing machine can work, which is also reflected in the service life of the entire unit as a whole. But still, I emphasize once again that the direct duration of the service life of the washing machine and the number of revolutions of the drum during the spin cycle are not related. Rather, how many years your “automatic laundress” will work depends more on the quality of the components. For example, since we are talking about bearings, some companies order them in Poland, but the quality of bearings from this country is worse than, for example, from Sweden, SKF. So it is advisable to choose a machine according to the configuration, and not according to the number of revolutions of the drum during the spin cycle.
What number of revolutions brings the car into the category of "high-speed" units?
Today, such models are considered capable of wringing with a drum rotation speed of more than 900 rpm.
Are there washing machines with a high drum speed special devices to reduce the inevitable noise and vibration? And in general, how does a “high-speed” machine differ from a conventional one, except, in fact, the speed of rotation of the drum?
Differs, for example, in the presence of a processor board that allows the user to independently change the number of revolutions of the drum in the process of setting up a washing program. In addition the presence of reinforced shock absorbers and suspension springs. As a rule, more modern ones are installed on such models. asynchronous motors. Recently, machines with a new type of motor have appeared in general it is “directly” connected to the drum. This avoids belt drive, one of the main sources of spinning noise. For example, LG already has such machines.
And yet, there is a direct relationship between the maximum number of revolutions of the drum and the spin class of the washing machine. The faster the drum spins, the drier the laundry as a result, the lower its residual moisture, which means the higher the spin class. Where is the limit, how much more you can increase the rotation speed 1600, 1800, 2000, maybe 2500 rpm is an ideal option?
Do not increase the number of drum revolutions indefinitely. If this is done, then the laundry will simply tear: microscopic holes will turn into small ones, small ones into large ones, folds on synthetics can become creases
What is optimal number revolutions?
Over 1000 rpm is not necessary. All the same, for washing wool, silk, fine fabrics, the limit is 500 revolutions. Synthetics cannot be wrung out at a speed of more than 900 revolutions (this is the maximum!). For some things, spinning is generally contraindicated. As for the notorious residual moisture content of the linen, if you compare it at 500 and 1000 rpm, the difference will be significant, and at 1000 and 1200 rpm it will be almost invisible. Residual humidity of 45% or less (which some manufacturers strive for) is achieved by complex and expensive technical solutions.
In which type of machines is it easier to “organize” high spin speeds: front-loading or top-loading?
On the one hand, the reliability of “vertical” washing machines is theoretically higher than that of “frontal” ones. This is due to the fact that in them the drum is fixed on both sides, and not on one side, as in front-loading machines. Naturally, this affects the service life of other parts, for example, bearings, which are “spaced apart” by “vertical” devices. different sides(according to the drum mounts). But on the other hand, the level of vibration during the spin cycle of such washing machines, in general, is greater due to the design features. Therefore, now there is little difference between the types in which one is more suitable for wringing on high revs no.
Are there alternative methods of spinning clothes?
It is difficult to call them alternative, rather it is a symbiosis of methods in which you can wring out the laundry at a “sane” number of revolutions of the drum, and then dry it with a tumble dryer or a washer-dryer. But there are some downsides. For example, there may simply not be enough space to install a dryer. After all, the bathrooms and kitchens in the apartments of many people are not very large, and not everyone wants to put such a unit in the hallway or in the living room. Washing machines with dryers are distinguished by their small capacity. Drying in them, as a rule, can be no more than 3 kilograms of laundry, and, given that you can usually wash 56 kilograms , it turns out that the drying process will stretch into two stages, and this is additional time, and electricity consumption. By the way, many dryers generally do not consume electricity very economically. Basically, their energy class is higher than C. In addition, you need to be aware that linen that is constantly dried in a “machine” way wears out faster. This is due to the fact that no matter how hard the manufacturers try, no matter how they improve the drying process, the fibers of the fabrics do not always warm up evenly. In some places, a banal overheating occurs, the thing dries out and the fabric becomes thinner.
Conclusion
Well, it seems to us that now everything that is called has fallen into place. The desire of the manufacturer to impress the imagination of the buyer is understandable. After all, the technique must be sold in order to make a profit. But the catch is that in the process of automating washing, almost everything that the modern development of technology has allowed has been invented. Breakthroughs and revolutions are not yet worth waiting for. So the "poor" firms that produce household appliances have to come up with something out of nothing to attract buyers to their new models. "High-speed" spin just from this series.
We hope that those who used to pay attention to this parameter when buying a washing machine - spin speed, will reconsider their approach after our material. Of course, we do not urge not to be at all interested in how the machine wrings out. But chasing "quintals per hectare" with a large number of revolutions of the drum during the spin cycle is certainly not worth it. Be sure 1000, maximum 1200 rpm is enough for high-quality spinning of terry dressing gowns, sheets and towels. We do not recommend pressing everything else at such speeds.
There is, of course, still such a thing as prestige. For some, it is especially important that everything is better for them than for others. But believe me, if you buy a Swiss Schulthess washing machine (for example, the Spirit XL 1800 CH model) for 75,000 rubles, it will amaze the imagination of neighbors and friends with its cost alone, and, perhaps, design. Of course, you can squeeze out something unnecessary, at a speed of 1800 rpm, but only if you really don’t need it.
In general, the choice, as always, is yours. We just want it to be meaningful.
The characteristic of the turbojet engine in terms of the number of revolutions is curves that show the change in thrust and specific fuel consumption with a change in the number of revolutions (at constant speed and flight altitude).
The characteristic by the number of revolutions is shown in fig. 41.
When the thrust is changed by revolutions, the following main modes of engine operation are noted:
1. Idle throttle or RPM idle move. This is the lowest speed at which the engine runs stably and reliably. At the same time, stable combustion occurs in the combustion chambers, and the turbine power is quite sufficient to rotate the compressor and units.
For turbojet engines with centrifugal compressor idle speed is 2400-2600 per minute. Engine thrust at idle does not exceed 75-100 kg.
Idle speed accrual specific consumption fuel is not a characteristic quantity; this is usually the hourly fuel consumption.
At idling speeds, the turbine operates in severe temperature conditions, in addition, the oil supply to the bearings is very small. Therefore, the time of continuous operation at low gas is limited to 10 minutes.
2. Cruise - the engine is running at speeds at which thrust is approximately 0.8 R MAX.
Rice. 41. Characteristics of the turbojet engine in terms of the number of revolutions.
At these speeds, continuous and reliable operation of the engine is guaranteed for due date service (engine resource).
The designer selects the engine parameters in this way (ε, T , efficiency) in order to obtain the lowest specific fuel consumption in cruising mode.
The cruising mode of operation of the engine is used for flights of duration and range.
3. Nominal mode - the engine operates at a speed at which the thrust is approximately 0.9 R MAX.
Continuous operation in this mode is allowed no more than 1 hour.
In the nominal mode, climb and flights at high speeds are made.
According to the nominal mode, the thermal calculation of the engine and the calculation of parts for strength are carried out.
4. Maximum (takeoff) mode - the engine develops maximum number revolutions, at which the maximum thrust R MAX is obtained - in this mode, continuous operation is allowed for no more than 6-10 minutes.
Maximum mode used for takeoff, climb and short-term flight at maximum speed (when it is necessary to catch up with the enemy and attack him).
The characteristic by the number of revolutions is built under standard atmospheric conditions: air pressure P O = 760 mm rt. Art. and temperature T 0 = 15 0 С.
Rice. 42. Change in specific fuel consumption by the number of revolutions.
With an increase in the number of engine revolutions (at constant altitude and flight speed), the second air flow through the engine G SEK and the compression ratio of the compressor ε COMP. As a result, the engine thrust sharply increases and the specific fuel consumption decreases, the turbojet engine is more economical at high speeds. If the specific fuel consumption for maximum speed taken as 100%, then the specific fuel consumption at idle speed will be 600-700% (Fig. 42). Therefore, it is necessary to reduce the operation of the turbojet engine at idle speed in every possible way.
5. Fast and furious. For engines with an afterburner, the characteristics also indicate thrust, specific fuel consumption and the duration of the engine when the afterburner is turned on - the afterburner.
When starting the turbojet engine, the initial spin-up of the shaft to the idle speed is carried out by an auxiliary starting engine.
As starting motor used: electric starters, starter-generators, turbojet starters.
The electric starter is an electric motor direct current, powered by current from aircraft or airfield batteries during launch. Its power is about 15-20 liters. With.
On some turbojet engines, a starter-generator is installed, which, when started, works like an electric motor, and while the engine is running, it works like a generator - it feeds the aircraft network with current.
An electric starter, or starter-generator, is included in automatic system launch, and its work is coordinated with the work of the launcher fuel system and ignition systems.
The turbojet starter is an auxiliary turbojet engine installed on powerful turbojet engines.
A small electric motor drives a turbojet starter that spins the main engine to idle and shuts down automatically.
Setting up a chainsaw carburetor with your own hands
For an independent carburetor option, you need to familiarize yourself with its device and understand the procedure for the work that is carried out to adjust the parts responsible for the correct functioning constituent parts device and parts close to it.
It is necessary to carefully handle the items for the system option, and also determine the compliance of the set characteristics with very acceptable values.
About the carburetor device
The carburetor serves to mix the combustible mixture with air, subject to predetermined proportions. If clear doses are not observed, the correct operation of the motor is at risk. When a huge amount of air enters during mixing, and there is not enough fuel, then such a mixture is considered "poor".
Oversaturation should not be allowed, because with a large amount of fuel compared to air, malfunctions or engine wear are also likely. Carburetor adjustment is needed not only before the initial implementation, but also when any differences in its operation are detected. Before you start working with a chainsaw, do not forget to break it in.
Components of a carburetor
The design of the carburetor contains standard set parts, but may vary slightly depending on the manufacturer. Components:
- The basis. This is a special tube that visually resembles an aerodynamic design. Air passes through it. A damper is located in the transverse direction in the middle of the pipe. Its position can be changed. The more it is extended into the passage, the less air enters the engine.
- Diffuser. This is the narrowed part of the tube. With its help, the air supply speed is increased precisely in the segment where the fuel comes from.
- Channels for fuel supply. The fuel mixture is contained in the float chamber, then passes into the jet, from which it flows into the atomizer.
- float chamber. It is a separate structural element, reminiscent of the shape of the tank. Designed to constantly maintain optimal levels fuel fluid before entering the channel from where air enters.
Don't know which chainsaw to choose? Read our article.
Looking for cheaper models, but reliable and time-tested? Pay attention to Russian-made chainsaws.
Or study foreign manufacturers chainsaws such as Stihl.
What you need to have to set up
Every carburetor owner should have necessary tools to adjust this system. There are three adjustment screws that are located on the body of the device. They have their own markings:
- L - screw for correcting low speed.
- H - screw for adjusting high speed.
- T - regulates idling, in most cases it is used for experiments.
Chainsaw air filter
Before adjusting the carburetor, you need to prepare the device:
- The engine warms up, that is, it starts up about 10 minutes before repair, and turns off at the start of work (see how to start a chainsaw).
- Check and clean the air filter.
- The chain is stopped by turning screw T as far as it will go (see chain oil).
To carry out a safe repair, you need to prepare a flat surface where you can carefully position the device, and turn the chain in the opposite direction. You need a tachometer. It determines the presence of a violation in the operation of the carburetor. When turning the screws, the sound should be perfect and absolutely even. If squealing notes are noticed, then the mixture is oversaturated.
Setting instructions
Carburetor adjustment is divided into two main stages. The first is called basic. It is done with the engine running. The second is performed when the engine is warm.
To complete the carburetor tuning procedure successfully, You need to read the instruction manual beforehand. specific model to identify additional features device settings.
First stage
The adjustment screws for the highest and lowest speeds should be turned clockwise until the highest resistance is met. When the screws reach the stop, you need to transfer them to reverse side and leave at the passage of 1.5 turns.
main stage
Chainsaw STIHL 180 check how many revolutions it turns
In this video we will answer the question of how to tune or adjust the carburetor chainsaws do it yourself
Chainsaw STIHL 230 check how many revolutions it turns
Carburetor adjustment chainsaws Champion 254 DIY. Initial carburetor adjustment shown
The engine turns on at medium speed and it warms up for about 10 minutes. The screw responsible for adjusting the idle speed must move clockwise. It is released only when the engine enters the stable operation mode. It is necessary to check that the chain does not move during this process.
In idle mode, the engine may stall (the reason is here). In this case, you must immediately bring the adjusting screw clockwise to the stop. Sometimes the chain starts to move. In this case, turn the adjusting screw in the opposite direction.
Checking the operation of acceleration
You need to do a little research. Device acceleration is initiated. It is necessary to evaluate the serviceability of the engine during the maximum speed. When the engine is running correctly, when you press the accelerator, the speed quickly increases to 15,000 rpm.
If this does not happen or the increase in speed is too slow, the screw marked L must be used. It turns counterclockwise. Moderate movements must be observed, since the turn cannot be more than 1/8 of a full circle.
Max RPM
To limit this figure, you need to use a screw marked H. To increase the number of revolutions, turn it clockwise, and to reduce them in the opposite direction. The maximum frequency should not exceed 15000 rpm.
If this indicator is made larger, the engine of the device will wear out, which will lead to problems in the ignition system. When rotating this screw, the ignition processes of the device must be taken into account. If the slightest failures appear, then the maximum speed value must be reduced.
Final check at idle
Before this procedure, it is necessary to perform a full adjustment of the carburetor components when operating at maximum speed. Next, you should check the operation of the device in idle cold mode. When the correct parameters are reached when adjusting, you can see the exact correspondence of the carburetor design to the following criteria:
- When the idle cold mode is connected, the chain does not move.
Chainsaw Accelerator
- When even a slight pressure on the accelerator is carried out, the engine is gaining momentum at an accelerated pace. With a gradual deepening of the pressure, you can notice that the engine speed increases commensurately, reaching the maximum allowable values.
- When the engine is running, you can compare its sound with a four-stroke device.
If there are violations in the given parameters or the device was not fully adjusted, you need to perform the main setup step again. Sometimes actions are performed incorrectly. In this case, the device may fail due to the loss correct settings node. In this case, you will have to contact a specialist.
Dismantling the carburetor if necessary to check or repair components
Device different models carburetors are almost the same, so when working with them, you can use the standard scheme. All elements must be removed carefully, and then post in the order below so that you can successfully arrange items in place at the end of the repair work.
Read:
Removing the Top Cover
- Filmed top cover. To do this, unscrew the 3 bolts holding it in a circle.
- The foam rubber is also removed, as it is the top integral part air filter.
- The fuel hose is removed.
- The drive thrust is displayed immediately on it.
- The end of the cable is disconnected.
- The petrol hose can be completely removed by systematically pulling it off the fitting.
To finally prepare the carburetor for a major overhaul or replacement of the smallest parts, you need to carefully disconnect it from the main system. Sometimes further disassembly is required. Should be unscrewed constituent elements carefully and fold the fasteners in groups, as these small parts are easily lost.
Instruction for Chinese
To properly set up the carburetor of a Chinese chainsaw, you must first remember the factory settings of the device, then turn on the engine. Subsequently, you will have to leave it running for several hours in order to accurately set your own parameters. Sometimes work is performed once after ten minutes of engine operation, however, many models Chinese made require special handling.
Chinese chainsaw model
Adjustment procedure:
- Activities start in idle mode. With the help of adjusting screws, you need to achieve a systematic increase in engine speed, so you should first let it work at low speeds. The deviation from the norm is the movement of the chain along the tire. In this case, you need to adjust the outer screws to the optimal position so that the chain remains stationary.
- Turnover is in progress average speed . Sometimes the engine will smoke. This defect can be eliminated by tightening the screw to supply a leaner fuel mixture.
In this case, the smoke will disappear, but the engine speed will increase. It is necessary to adjust the settings until it reaches a level where, when you press the throttle, the engine smoothly picks up speed, you can’t hear sharp jerks or interruptions.
The mode of operation of the engine is one of the main factors affecting the wear rate of its parts. It's good when the car is equipped automatic transmission or a variator that independently chooses the moment of transition to a higher or lower gear. On machines with “mechanics”, the driver is engaged in switching, who “spins” the motor according to his own understanding and not always correctly. Therefore, motorists without experience should study at what speed it is better to drive in order to maximize the life of the power unit.
Low speed driving with early shifting
Often, driving school instructors and old drivers recommend that beginners drive “in tightness” - switch to top gear upon reaching 1500–2000 rpm crankshaft. The first give advice for safety reasons, the second - out of habit, because before the cars had low-speed engines. Now this mode is only suitable for a diesel engine, whose maximum torque is in a wider rev range than a gasoline engine.
Not all cars are equipped with tachometers, so inexperienced drivers with this style of driving should be guided by speed. The early shift mode looks like this: 1st gear - moving from a standstill, shifting to II - 10 km / h, to III - 30 km / h, IV - 40 km / h, V - 50 km / h.
Such a shifting algorithm is a sign of a very relaxed driving style, which gives an undoubted advantage in safety. The downside is an increase in the wear rate of parts of the power unit, and here's why:
- The oil pump reaches its nominal capacity from 2500 rpm. Loading at 1500–1800 rpm causes oil starvation, especially suffer connecting rod bearings sliding (liners) and compression piston rings.
- Burning conditions air-fuel mixture far from favorable. In the chambers, on the valve plates and piston bottoms, carbon deposits are heavily deposited. During operation, this soot is heated and ignites the fuel without a spark at the spark plug (detonation effect).
- If you need to rev the engine sharply when driving downhill, you press the accelerator, but acceleration remains sluggish until the engine reaches its torque. But as soon as this happens, you shift into a higher gear and the crankshaft speed drops again. The load is large, there is not enough lubrication, the pump poorly pumps antifreeze, hence overheating occurs.
- Contrary to popular belief, there is no fuel economy in this mode. When you press the gas pedal fuel mixture is enriched, but not completely burned, which means it is wasted.
Owners of vehicles equipped with on-board computer, it is easy to be convinced of the uneconomical movement "in tightness". It is enough to turn on the display of the instantaneous fuel consumption.
This type of driving wears out power unit when the vehicle is being operated difficult conditions- on ground and country roads, fully loaded or trailer. Do not relax and car owners with powerful motors with a volume of 3 liters or more, capable of accelerating sharply from the bottom. After all, for intensive lubrication of rubbing engine parts, you need to keep at least 2000 rpm of the crankshaft.
Why is high crankshaft speed harmful?
The driving style “sneaker on the floor” implies constant crankshaft spinning up to 5–8 thousand revolutions per minute and late gear shifting, when engine noise literally rings in the ears. What is fraught with this driving style, in addition to creating emergencies on road:
- all components and assemblies of the car, and not just the engine, are tested maximum loads during the service life, which reduces the total resource by 15–20%;
- due to the intense heating of the engine, the slightest failure of the cooling system leads to a major overhaul due to overheating;
- exhaust pipes burn out much faster, and with them an expensive catalyst;
- transmission elements wear out rapidly;
- since the crankshaft speed exceeds the normal speed by almost twice, the fuel consumption also increases by 2 times.
The operation of the car "at break" has an additional negative effect associated with the quality pavement. Movement on high speed on rough roads literally kills the suspension elements, and in the shortest possible time. It is enough to fly the wheel into a deep pothole - and the front strut will bend or crack.
How to ride?
If you are not a race car driver and not an adherent of tight driving, who finds it difficult to retrain and change driving style, then to save the power unit and the car as a whole, try to keep the engine operating speed in the range of 2000-4500 rpm. What bonuses will you receive:
- Mileage up to overhaul the motor will increase (full resource depends on the brand of car and engine power).
- Thanks to the combustion of the air-fuel mixture in the optimal mode, you can save fuel.
- Fast acceleration is available at any time, you just need to press the accelerator pedal. If there is not enough speed, immediately switch to a lower gear. Repeat the same steps when moving uphill.
- The cooling system will function in operating mode and protect the power unit from overheating.
- Accordingly, suspension and transmission elements will last longer.
Recommendation. On most modern cars equipped with high speed gasoline engines, it is better to shift gears when the threshold of 3000 ± 200 rpm is reached. This also applies to the transition from higher to lower speed.
As stated above, dashboards cars don't always have tachometers. For drivers with little driving experience, this is a problem, since the crankshaft speed is unknown, and the beginner does not know how to navigate by sound. There are 2 options for resolving the issue: buy and install on a dashboard electronic tachometer or use the table, which shows the optimal engine speed in relation to the speed in different gears.
| Position of the 5-speed gearbox | 1 | 2 | 3 | 4 | 5 |
| Optimum crankshaft speed, rpm | 3200–4000 | 3500–4000 | at least 3000 | > 2700 | > 2500 |
| Approximate vehicle speed, km/h | 0–20 | 20–40 | 40–70 | 70–90 | over 90 |
Note. Considering that various brands and modifications of machines, there is a different correspondence between the speed of movement and the number of revolutions, the table shows the average indicators.
A few words about coasting from a mountain or after acceleration. In any fuel supply system, a forced idle mode is provided, which is activated under certain conditions: the car is coasting, one of the gears is engaged, and the crankshaft speed does not fall below 1700 rpm. When the mode is activated, the supply of gasoline to the cylinders is blocked. So you can safely brake the engine on top speed without fear of wasting fuel.
