Today’s webmaster’s classroom is aimed at machinery-related questions, answering readers and audiences, such as the need to train a car, the working principle of various clutches and clutches, and the difference between front and inverted forks. Hope Can help you understand, let’s take a look with Moto7!

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The need to train a car

The so-called training is Run in, and the engine needs Run in. In fact, in addition to the engine, the entire gearbox requires a lot of mechanical cooperation. Where there is a match, it needs to be trained. At the same time, you can find out if there are any problems with the mechanical structure of the vehicle during the training process. This must be tamed! Like the station master’s own R6 before going on the track, he used the roundabout to do a quick training car. Of course, during the training process, when to change the oil is also an important point.

We can also give some examples of the reverse. When you have ridden the oil after riding for about 300 kilometers, you will find that there are still a lot of metal shavings inside. This is the reason you must train the car. The engine needs to go through Run in, it will produce a lot of iron filings in the oil. If you haven’t used a milder riding style during this period, these iron filings will definitely follow the oil to run between the cylinder and the piston to cause scratches, so it is very clear that you must use a milder riding style. The way is to ride in the initial stage, and then slowly increase regardless of the speed, the degree of throttle, and slowly increase, so it is necessary to train the car.

For example, the stationmaster has a friend who often repairs KTM cars. With Run in and without Run in, there can be a difference of at least 5% of the horsepower; and if there is no Run in action, the engine may be at a certain mileage. After counting, it is obvious that a single cylinder eats engine oil. For single-cylinder, due to the imbalance of the engine, there must be some wear on the front and back of its pistons, and it will be more serious than ordinary two-cylinder cars or four-cylinder cars, so if you don’t do it well The action of Run in will soon have these wear and tear, will eat engine oil soon, and there will be absolute differences in horsepower; this is a model that has been ridden and repaired by KTM, especially this large single cylinder is particularly obvious. So you must Run in!

Let’s take an example just now. If you drain the oil at 300 kilometers, there will still be a lot of metal scraps in the oil, so you must do a slow and slowly increase the engine load. Use this For example, in the case of R6, its red line speed is 16,000 rpm, but when I was riding in the first 300 kilometers, I only mentioned about 6,000 rpm, and the first 300 kilometers only reached After 6,000 rpm, after three hundred kilometers, I quickly changed the oil and found that there were actually a lot of iron filings inside.

After another three hundred kilometers to one thousand kilometers, I started to increase the speed, probably to 10,000 rpm, so in the middle I started to increase slowly from 6,000, 7,000, 8,000, 9,000, 10,000, and then at 1,000. When I changed the engine oil at kilometer, there were still some iron filings in it. After I went on the track, in fact, every two or three hundred kilometers, I would ride it once or twice on a track day. Change the oil to ensure that the engine is in good condition, so you must train the car. This is basically the part of the engine pistons and cylinders. Of course, this part can also be used, for example, if you have ridden a factory car. Experience, if the car shop has ever repaired a factory car, you can actually use some chamfers in advance to make the entire piston and the piston ring and the cylinder wall fit better. But for a brand new car, the more important thing is the gears. For a geared car, the six gear ratios and 12 gears are used in the entire gearbox. They are all lubricated with oil, and they will produce more iron filings. , If these iron filings do not run in, do not change the oil early, or ride in a slower way, these iron filings will still run between the cylinder piston and the piston wall.

In addition to paying attention to the cylinder and piston walls, more attention should be paid to the gears, because their accuracy is often relatively low. In terms of the precision of machining, they are usually worse than the piston and the cylinder wall. The iron filings are more important to pay attention to, so you must not be superstitious in the so-called violent training method before riding. If you use violence to train the vehicle, it is possible that these iron filings will still enter the piston and the cylinder wall and cause scratches. Therefore, it must be done step by step, and the car must be warmed up, and then the oil should be changed early if possible.

Clutch type

Dry centrifugal clutch

I think there are two types of clutches, one is the dry centrifugal clutch with speed reach, and the other is the multi-disc and wet clutch commonly used on gear cars. First of all, let’s discuss the dry clutch. This kind of centrifugal dry clutch, if you have dismantled the transmission case of the Scooter, you will see a bowl, and there is a set of clutch plates on the surface of the bowl. When its speed and engine are like this When the transmission speed reaches a certain level, it will throw away the clutch plate, and it will expand. After it is thrown away, it will rub against the inside of the bowl. When its speed reaches a certain value, it will It will hold the bowl and go and rotate together. This is from the original semi-clutch friction, dynamic friction to static friction, these two will rotate together, and this is the centrifugal clutch above the speed.

The centrifugal clutch has several characteristics. Of course, when it is not moving at all, it is pulled by the spring and shrinks; then when it starts to rotate, according to the speed, it will turn faster and faster. At first the clutch plate will be thrown away, and then when it starts to rub against the inside of the bowl, it will drive the bowl to start to walk, so when you press the accelerator, you will feel that the car seems to be about to go, if you clutch and bowl at this time The friction between them is uneven. Maybe the bowl is deformed or the clutch plate may have excessive abrasion. At this time, the car will shake. It seems to be shaking all the time and then start. This is because of the bowl or the clutch plate. The fit is no longer good, usually because the bowl is deformed, because it may be deformed in the end due to thermal expansion and contraction.

The second characteristic of the centrifugal clutch is that when they are combined, there is a so-called self-locking effect, that is, it will not separate again, because the direction of its force is just to pull it open and open at high speed. , No matter how great the power is, it will not break away again, only at low rotation, that is, when the speed becomes slower and slower, when it turns slower, it shrinks and is pulled back by the spring, and then the two break away, so when our speed decreases At that time, I suddenly felt that the car was sliding, and there was originally the power of the engine brake, but when the speed may be as slow as maybe five kilometers, I suddenly felt that the car was sliding forward. It was because they were separated, so The rear wheels are separated from the engine. Otherwise, if the rear wheels stop, the engine will be stalled. But because they are separated, the engine can continue to idle and run. This is the dry centrifugal clutch that can be reached. .

Multi-plate wet clutch

It is a multi-disc wet clutch on the gear car. The so-called wet type is that it is lubricated by organic oil. Why is it necessary for oil lubrication? The first is that it can cool down, the oil will take away the heat of the clutch, the second it will take away the debris worn down by the clutch plate, and the third is that it can lubricate between the clutch plate and the friction plate. When they are separated, there is still oil in the lubrication, so they can be separated or joined smoothly, which is lubricated by the oil in the inside.

In the case of wet clutches, the so-called wet type is engine oil, which takes away heat or debris, and then it is used for lubrication, so that they can move more smoothly. The multi-disc clutch is controlled by the left hand in the case of a gear car, that is, when you pull the clutch, it will have a push rod to open the clutch, and the clutch plate and friction plate inside can rotate freely, so The crankshaft engine has nothing to do with the rear wheels, but as we gradually release the clutch, the pressure plate of the entire clutch will begin to loosen, and it will be pressed together by the spring. At this time, the clutch plate and the friction plate After friction and engagement, the engine can rotate with the rear wheels, so when you gradually release the clutch, you can feel that the proportion of power transmission reaches the rear wheels more and more, driving the rear wheels to move. This is the gradual release. In the process, their clutch plates and friction plates are compressed more and more densely. They originally drive friction with each other. The last two are integrated, and their speed is the same. This is the basic structure and operating principle of the clutch.

The impact of semi-clutch on the vehicle

The so-called half-clutch is when you fully grasp the clutch, we say it is 100% clutch, half-clutch is between full release and full grasp, maybe you pull a little clutch, then you will find that the engine speed is still free The ground is pulled up, but it will accelerate the vehicle slightly. For example, when we are starting, it is a semi-clutch start. From the original full clutch, we start to release some, maybe 50%. It starts to rub, and the power of the engine can drive the body. This is the so-called Semi-clutched condition. At this time, we usually wait for it a little bit to make it a little bit more, and after the speed is brought up, it will be fully released, or it is a process of gradually releasing, more and more; then it actually has a point, that is, it is already rubbing. You can also use the throttle to bring a little more power and start faster. This stage is the so-called semi-clutch.

If you use the semi-clutch frequently, or it takes a long time to operate the semi-clutch, for example, when it is possible to start, let it continue to rub, and it takes a long time to completely go out. Maybe others may completely let it go after a little rub. If you keep rubbing with you, rubbing out, the consumption of the two will be different. The so-called consumption means that the consumption of the clutch disc will be different. For ordinary daily commuting, there must be a concept. The clutch disc is indeed a consumable item, but if you use it excessively, you may need to change the original mileage of 20,000 kilometers. At this time, you may need to replace 3,000 kilometers, and your lifespan is relatively short. Just like the brake pads, this is actually a consumable, and the discs are also consumables, but if your life is over Short, it actually hurts your wallet!

Usually I would say that this is an abnormal wear or excessive wear. In fact, it does not cause excessive damage to the vehicle, but it wears faster and needs to be replaced more frequently. The half-clutch is one of them. In addition to starting, you may use a semi-clutch situation, perhaps at low speeds. For example, when turning at low speed, when the engine speed is a little too low, you will pull the clutch a little, because the engine speed is too low, it may be about to stall, and it has entered a near idle speed or even lower. At this time, you will grab the clutch. At this time, you can also use the half-clutch method. Don’t grab it all. Just grab a little bit. After bending over, release the accelerator and then release the clutch. The concept of starting, this is the time to use the semi-clutch. Some people may say, for example, that they might have been driving on a normal road and suddenly decelerated. At this time, you can use a semi-clutch mode to accelerate out again, or you can also retreat. Some people may just use the semi-clutch mode. If the clutch is used to accelerate again, it will not retreat, and use a slightly semi-clutched way to accelerate out. Of course, if you often operate in this way, its wear will be faster. This is another side effect behind it!

Shift without clutch? Fast forward and backward?

As far as the driving training class is concerned, you need to pull the clutch when you change gears, whether it is downshifting or upshifting, but in fact, for upshifting, because its speed is in the process of upshifting. It will fall naturally. It does not go up. When the engine is not working, its natural speed will fall down. So when upshifting, we can use this feature to directly upshift. Generally speaking, we The method of operation is the so-called upshift without the clutch. When the speed has been pulled to a certain level and it is necessary to change gears, at this time, you only need to lower the throttle and operate the gear lever to upshift. You will find that it is easy to shift The gears are shifted over, because when you release the throttle, its speed will actually drop. Just in line with the upshift, its speed will drop a bit, and you can easily change gears.

Conversely, if you want to downshift, because the essence is to increase the speed, it is difficult for you to increase the speed during this process, so you cannot directly reverse the gear without pulling the clutch. Even if you do not pull the clutch directly, you will I found that the frustration is very serious. In fact, because of the frustration, you probably intuitively know that this is not suitable. If you want to do this, the engine must have abnormal wear and tear, and it may end class early. Even after one or two times, some of the gears that are processed poorly may collapse, and they will break.

In terms of the current public upgrade imitation or 600-level distance, almost all are equipped with forward and backward fast platooning. At this time, as long as you maintain the throttle when accelerating, it will interrupt ignition or interruption whenever you upshift. The fuel injection method makes the speed fall automatically, and then automatically connect up; if you want to retreat, you must keep the throttle state at this time, you directly retreat, and the electronic throttle will help you make a fuel supplement action. At the moment you step down, it helps you to make up the throttle, allowing you to make a gear connection, so the electronic control is now helping you, whether it is the electronic control to help you with the throttle, the ignition or the fuel, In other words, it secretly helps you make up more throttle so that you can better retreat. This is a basic principle of forward and backward fast shifting.

What effect does the thickness of the inner tube diameter of the front fork have?

The thickness of the shock absorber, for the front fork, because everyone knows that the diameter of the inner tube will be given on the specification sheet. Is it better to be thick or thin? Or what? There will be a difference here. In terms of suspension, the function of the entire suspension is to stabilize the car body. It must isolate the vibration from the road surface, or for the front fork, it can be free to expand and contract to isolate the vibration from the road surface. In addition to maintaining the stable forward movement of the body, due to its mechanism design, the front fork must support the braking force. If we draw the picture, you will find that the front fork must support the entire car when braking, and then the weight from the back forward, if it is bent, if the front fork is bent in the process of supporting the weight, it will be bent. Affecting the action means that if the outer tube and inner tube of the front fork can be bent, it will not move smoothly. Logically speaking, they should move in a straight line, but when you are bent, it will move incorrectly. So its rigidity is very important.

Therefore, the thicker the front fork, the better its rigidity in general, and the better it can withstand a deceleration when braking. Of course, in addition to the entire braking deceleration, when cornering, the lateral force is either in acceleration, or when the front wheel is shaken, the thickness of the entire front fork also affects its ability to withstand The force of the direction, so not only the force when decelerating, but also the acceleration or the left and right speeds must be able to withstand. So the basic principle is that the thicker it is, the more it can withstand the force, and the less deformation. This is The so-called rigidity.

Is the thicker the better? In fact, the thicker it is, the weight will be relatively heavier, so the weight of your car will become heavier. If you think it is too thick, your upper and lower triangular platform will inevitably increase, and the weight will be increased. Become heavier. Or in terms of the car body, your body may be originally thin, but the front fork becomes so thick, so the body must be enlarged, and the entire weight will be added together. This is a basic concept when we design a car; you Will do the matching, that is to say, the horsepower and speed of this kind will match the approximate diameter of the front fork is suitable. If the matching is not good today, it may cause excessive weight or other components. It has to be larger, and the weight is always added. It may have been expected that this car will have such an acceleration of 250c.c. In the end, because the weight will become heavier, the horsepower may have to increase again. When the horsepower is increased again, the car will again It has become heavier, so the thickness of the front fork has to be increased again, and there will be an endless loop. Therefore, the horsepower and weight of the vehicle must be set at the beginning, and the approximate diameter of the front fork is suitable. Decide at the beginning.

The difference between a fork and an inverted fork

First of all, discuss the benefits of the inverted fork. This has something to do with the design of the entire mechanical structure. I have been talking about the thickness of the inner tube of the front fork. This is usually an indicator, but how the entire front fork can withstand the force of the rear wheel What? Another important point is the outer tube and the inner tube. The length of their contact is the place that can really effectively support the deceleration of the entire vehicle. For the front fork, because its design is the inner tube on the top and the outer tube on the bottom, the contact area or length of the inner tube and the outer tube is relatively small, but if we use an inverted fork Since the outer tube and the inner tube are inside, the contact area or length is relatively large, so the rigidity it can bear in this section is also relatively good.

Generally speaking, we would say that the rigidity of the inverted fork is better. In fact, the point is that the intersection between the outer tube and the inner tube is longer, and the torque they can withstand is better. From a performance point of view, there is no doubt that the performance of the inverted front fork will be better. Otherwise, why does MotoGP or the current public upgrade, 600-class imitation racing car use an inverted fork? This is a relatively simple reason. Of course, there are some special cases. For example, in some special applications, such as some American cruise locomotives, you may want to change the entire front fork to a very long time. At this time, the more suitable modification is to use the forward fork. Increase the length of the inner tube so that the longer one extends below; if you want to change the inverted fork, it is relatively difficult to change the outer tube to a very long length. If you use the inner tube to change it, it will be more difficult. simple. Therefore, in different applications, some people may think that the front fork is better, but in terms of performance indicators, it depends on the current MotoGP factory cars, or the general Japanese imitation racing cars, and the application places where performance is the indicator. It is an inverted fork, which is a simple truth.

Principle of Tweet

Why do I need electricity to start the car? There are probably several parts. The first is that our starter motor needs electricity, which needs to be driven by the vehicle’s engine. The second part needs electricity is the injection fuel supply of the current fuel injection engine. It actually needs to be powered by a motor. Pressurize, so that the fuel can be injected into the engine, so if you want to start the car by pushing, it is probably mainly to use the power of the vehicle to turn the engine; if it is a fuel injection car, there is no electricity at all. Under the circumstances, it is actually very difficult, or even impossible, to rely on your accumulated electricity to push the accumulated electricity to fill the pump with sufficient fuel.

Generally speaking, if it’s a car with a carburetor, it’s easier to use a vehicle to push, because with the power of the push to turn the engine, you have the opportunity to start the vehicle. A gasoline-powered car has no electricity at all. It is difficult to power the engine by pushing. Unless you still have a small amount of electricity, it can at least provide a gasoline pump to accumulate the pressure of the oil’s power. At this time, you Then turn the engine up by pushing, so that the fuel injector can inject gasoline into the cylinder to ignite, and then start the engine, otherwise it will be difficult.

What effect does lowering the height of the vehicle have on the vehicle?

Generally speaking, if you are really petite, then I would suggest you to buy a suitable vehicle; if you still want to challenge a higher car model, it is best to find a version with a lower seat height; if not The low-seat and high version, and its rear suspension adopts a multi-link suspension form. Indeed, there is a kit in the shop to change the length of one of the tie rods in the multi-link to cause the body to be lowered. This way There will be a risk that when you change the height of the car through the combination of these linkages, the lever ratio of the entire suspension may run away. It is not the suspension form set by the original factory, so unless The designer has done research on the entire multi-link of the entire suspension and its rocker arm action. Otherwise, you must not easily reduce the height of the vehicle through this method, because the performance of the entire vehicle will be similar to that of the original manufacturer. It is completely different. It takes a test to know whether such performance will greatly affect the original performance.

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