Trafik kazalarında teknik kontrol
Technical problems in traffic accidents
- Tez No: 66592
- Danışmanlar: DOÇ. DR. GÜVEN ÖZTAŞ
- Tez Türü: Yüksek Lisans
- Konular: İnşaat Mühendisliği, Civil Engineering
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 1997
- Dil: Türkçe
- Üniversite: İstanbul Teknik Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: İnşaat Mühendisliği Ana Bilim Dalı
- Bilim Dalı: Ulaştırma Bilim Dalı
- Sayfa Sayısı: 70
Özet
ÖZET Trafik kazalarına insan ve yol faktörlerinden başka taşıtlar da neden olmaktadır. Bu çalışmada trafik kazalarına yol açabilecek taşıtlardaki teknik arızalar incelenmiştir. Taşıtlardaki donanım elemanlarının ve bu elemanlardaki muhtemel arızaların sürücü tarafından bilinmesi ve daha arıza meydana gelmeden gerekli önlemi alma doğrultusunda bilinçlendirilmesi, taşıtlardaki teknik sorunlardan dolayı meydana gelebilecek trafik kazalarının azalmasına neden olabilecektir. Taşıt donanımları üç bölüme ayrılır. Bunlar; ön takımlar, frenler ve lastiklerdir. Çalışmada bu üç donanım sırasıyla incelenmiştir. Ön takımlarda, direksiyondan başlanıp, sırasıyla rot sistemi, ön takımlar geometrisi, makas yayları, süspansiyon ve amortisörlerin işleyişleri anlatılarak, bu elemanlarda meydana gelebilecek arızalardan ve sonuçlarından bahsedilmiştir. Taşıtlarda tekerlek freni olarak sürtünmen' frenler kullanılır. Diskli ve kampanalı olarak ikiye ayrılan sürtünmeli frenlerde, bu iki tip frenin karşılaştırılması yapılmış, birbirlerine göre avantaj ve dezavantajlarına değinilmiştir. Ayrıca fren sistemi incelenerek arıza yapabilecek elemanlar ayrı ayrı ele alınmış ve bu elemanlardaki hangi arızaların kazalara yol açabileceği araştırılmıştır. Daha sonra bu konudaki gelişmelere ve özellikle Anti Blokaj Sistemlerine yer verilmiştir. Son olarak lastikler anlatılmış ve parçaları tanıtılmıştır. Hangi durumlarda arıza olabileceği incelenmiştir. Kazalara sebebiyet vermemek için gerekli önlemlere ve ayrıca bakım ve kontrolün önemine değinilmiştir. ıx
Özet (Çeviri)
TECHNICAL PROBLEMS IN TRAFFIC ACCIDENTS SUMMARY The numbers of the traffic accidents are getting higher day by day. And this means growing loss of lives and property. The causes of traffic accidents, firstly, are the human factors, and then comes the technical troubles in vehicles. In an analysis of a traffic accident, some reasons such as road conditions, technical troubles, disobedience to rules and regulations, and inexperience, are treated in order to make clear the reason of the accident. Yet some of these reasons can be found in an accident simultaneously. Only the technical problems in the vehicles leading the traffic accidents have been treated in this thesis. Technical troubles in the vehicles are divided into three groups: 1. Troubles in the front parts of the vehicle 2. Troubles in brake system 3. Troubles in tyre It will be given, as follows, the brief descriptions of the front parts, brakes, and wheels; and following the description of the parts likely to cause a trouble, the equipment of a vehicle shall be studied. 1. FRONT PARTS Steering Wheel: This is the mechanism which is used to steer the wehicle in action towards the direction required on the way. Hydraulic mechanisms are being mostly used today in order to make the movement of the steering wheel easier. Front Parts: The front parts consist of joints which join the front wheels to chasis in complex forms, steering rods, and shock absorbing system. If we look at a vehicle from the front, we see that the front wheels are not in exact vertical position but somewhat turned inwards. The relations between the angles which exist between the front wheels and the joints and the chassis are called“front parts geometry”. The reason of the use of these various angles is to steer the vehicle easily, to stabilize the vehicle in bends, and to prevent the abrasion of the wheels. Four of the factors concerning the front parts geometry are realeted to the angle measure, and one of them to the length measure:Angles: a. Camber angle b. Steering swivel pin (king pin) angle c. Beaver angle d. Toe-out angle Length: e. Toe-in length Camber Angle: This is the angle between the point where the front wheels contact with the ground and the vertical. If the angle is outwards, it is called positive, and if the angle is inwards, it is called negative. It is require the camber angle to be positive, bacaue the wheels get a vertical position through the load. Steering Swivel Pin Angle: This the angle between the steering swivel pin and the vertical. It makes the steering wheel move easier, and prevents the abrasio of the wheels. Beaver Angle: On condition that the steering swivel pin is inclined backwards rather than the vertical, the angle formed is called beaver angle. It maintains the stability of the steering wheel. Toe-in Length: The front of the front wheels is much more closed than of the rear. Hence, the length difference between the front and the rear of the wheels is called toe- in length. It prevents the abrasion of the wheels. Toe-out angle: Toe-out is the angle between the chassis and the front wheels during a turn. Steering Rod System and Gears: Rod: There are various rod types to join the drop arm which is bound to the steering wheel gears and the steering wheel cranks of the front wheels. Once the balance wheel runs, the drop arm moves from right to left (to and fro in some vehicles). This movement is required to be conducted to the steering joints of the wheels through the rod system. Steering Wheel Gears: Its function is to conduct the turn movement of the balance wheel and its pivot the the steering wheel rods directly and in a forward way. Shear Springs: The springs are located between the chassis and the wheel. AHload of the vehicle is likely to press on the springs. The up and down movements because of the fault on the roads are not connected via the springs to the vehicle chassis and thus to the inner parts of the vehicle. Suspension: It can be classified in four groups: front suspension, rear suspension, independent front suspension and ball jointed front suspension. They block up the up and down movements of the vehicle. xiDampers: It is not only the springs which prevent the roughness of the road and make the traveling more comfortable, because the springs should be so soft to block up the road faults and also so firm not to conduct the up and down movements to the vehicle. It is impossible to form a spring twofold. Thus, it should be used a very flexible spring and a system which prevent the roughness of the road to be conducted to the vehicle and which can be used as a brake mechanism. This brake system in the car is called as“damper”s. FRONT PART TROUBLES 1. The rod heads can be break down because of the traveling on the faulty roads. 2. There can be gaps in the rods. If they are not changed on time or if they are broken, the steering wheel does not function. 3. The tyre can be torn away because of the outer effects. In such a case, it should be changed immediately. 4. If the air in the tyres are not suitable for the season, it can cause some troubles at the front parts of the vehicle. 2. BRAKES The elements of the brake system will be treated separately: Friction Brake: There are friction brakes in the vehicles as a tyre brake. The friction brakes are divided into two groups as drum brake and disk brake: a) Disk Brakes: In these kind of brakes, a metal disk which is put together with tyre in the same axis turns together with the wheel. A part which is called saddle and connected to the tyre suspension arms clutches the disk on a point. The linings which are in the inner part of the saddle, leaning against both the surfaces of the disk, apply an equal twofold pressure on the disk through a hydraulic press during the brake. Since there is an abrasion in all the friction brakes, there should be a gap adjustment. Thus, it is possible to make the lining always close to the disk. The smaller the gap is, the smaller is the gap in the brake pedal and the shorter the delay time is. b) Drum Brake: The surface of the brake in the drum brakes is cylindrical. The structures of the drum brakes are in three types: inner block, band, and outher block. The inner block brakes are used in the wheel brakes of themotorway vehicles. The band brakes are mostly used in the automatic gear boxes, and the outer block brakes in the rail vehicles. Heating in Brake Construction: The capacity for storage of the heating should be high in order to prevent the sudden heating of the brake. The high heat capacities can be obtained through the aluminum alloys. Moreover, the traveling wind should be located open to the ventilating effect in order to discharge the heat out as soon as possible. xiiWheel Blockage and Anti-Blockage Systems: Anti-blockage systems are the systems, which control the dynamic of the wheel that shifts from rolling to blocking and the brake forces, in a way to prevent the blockage of the wheels. ABSs enable the criteria such as stable travel, easy steering, and shortening the braking distance. BREAKDOWNS IN THE BRAKES 1. The brake switch turns on the rear brake lights. On condition that there is a trouble in the vehicle, this can cause an accident. 2. Servo brake makes the use of the pedal easier through the pressure from the motor. On condition that there is a hydraulic leakage servo brake, this function does not work. On the other hand, if there is some stoppage in the air flowing coming from the motor, the brakes do not work. 3. The central pump distributes hydraulic to four wheels. If the rubber gaskets of the pistons are defective, the central pump cannot apply the necesary pressure for braking. 4. Brake hydraulic tank is the place where the hydraulic oil is stored. Hydraulic level should be always under control. 5. Hand brake handle is completely manual. If it does not function, the rear brakes do not function, as well. 6. If there is abrasion in the brake shoes and linings, this causes the misdirection and slip during the journey. 7. The rare brake three-way-bush enables the distribution of the hydraulic oil coming from the front to the rear wheels. If there is a hydraulic oil leakage in the bush, there appears a pressure loss and the brakes do not function. 8. If the linings in the front disk brake shoes, this results for the brakes not to function properly. 9. Front disk brake hydraulic circuit is the mechanism which enables the distribution of the oil. If this circuit gets a hole on any point, there appears a hydraulic leakage and the brakes do not function properly. 3. WHEELS The functions of the wheels is to carry the load in order to make the vehicles run, to start and stop the movement, to keep the course and bend directions, etc. The part of the whole structure are as follows:. Rubber layer. Textile, steel or fiberglass cords. Steel wires xiiiWHEEL TROUBLES The troubles are mostly seen before the wheels are completey worn out. 1. A hole on the wheel, which is not recognized, can cause the growing air loss when the wheel grows warm, thus the wheel bursts out. 2. The new wheels can also be injured through the strikes. This, later, can cause deflating. 3. The shapes that the wheels are formed in the various weather conditions are as follows: LESS AIR: This causes the excessive flexibility. High temperature causes the burst of the wheel. Moreover, there can be abrasion on the outer parts of the wheel. MUCH AIR: It causes the reduction of the resistance of the wheel against the road defects. 4. Troubles arising from the high temperature: Temperature can cause stretching in the wheel. The more the wheel stretches the higher the temperature gets, and this results in the reduction of the resistance and the burst. 5. The harsh brakes and starts accelerate the speed of abrasion. 6. A wheel which the balance adjustments are not updated and other related groups of planes have very negative effects on the wheel. It also prevents to be achieved to the normal speed of the vehicle. There are two basic signs of the unbalanced situation. These are: strikes and lurching.“Strikes”can be seen in high speeds and are conducted to the steering wheel as the speed gets higher.“Lurching”is a kind of sign seen as the sway from side to side. If there exists one of the said two unbalanced situations, you should apply to the authorized service and be sure whether there is such an unbalanced situation. 7. The mechanical disorder in the front parts can cause the early and irregular abrasions. MEASURES AGAINST WHEEL TROUBLES 1. You should press enough air according to the load on the wheels. 2. The wheels should be inflated properly. If there is less or much air in the tyre, it causes to shorten the life of the wheel and to increase the risk for the accidents arising from the wheel defects. The breakdowns, which might occur in the various parts of the wehi-le equipment, can cause the traffic accidents. The number of the vehicles gets highei day by day, and the number of traffic accidents increases accordingly. xivThe troubles and results to be occured in the front parts, brakes, and wheels, respectively, are as follows: The lower articulation, lower pivot, dust cover, upper articulation, upper pivot allwhich are the parts of the steering wheel mechanism do not cause an accident, but these are because of the“gaps”in the said parts. In such a case, there comes a noise from the front part of the vehicle. This makes the vehicle uncomfortable. Rod edges can be break down on the defected roads. In such a case, the said parts should be replaced. On condition that there are some gaps at the rods, unless the rods are replaced and break down, you cannot use the steering wheel. On condition that the wheels are torn away, they should be immediately replaced. If the maintenance of the suspensions is regularly followed, there never be any accident. On the other hand, there might be a leakage through the washers in the calibre of the brakes in this mechanism. This causes the brakes not to function properly. The lower swing can only be broken down through an accident. Otherwise, this part is not expected to cause an accident. If there is a hydraulic leakage in the hydraulic dampers and spiral springs, the comfort of the vehicle can get worse. As the result of what we have talked so far, the parts which can cause an accident in a vehicle are rods, maintenance and control are very important for these parts. A possible trouble in the brake mechanism or brake switch can cause the rear stop signals not to function, and thus this increases the accident risk of the other following vehicle. What is interesting here is the fact that the driver who realizes the maintenance and control of his vehicle decreases the risk of accident not only for himself but also for the ones who travel around him. The most important part in the brake system which might cause an accident is the front and rear brake hydraulic circuits. If there is a hole on any part of this circuit, there becomes a hydraulic leakage and the brakes do not function properly. The other parts which might be hydraulic leakage are: front brake caliber, rear brake cylinders, rear brake three-way bush. The abrasion of the brake linings is another reason of the non functional brakes. The hand brakes are completely manual. On condition that there is trouble in hand brakes, such a situation casuses the slip of the vehicle on the slopes. The hydraulic oil tank should be especially cared in the brakes. The hydraulic oil should be continuously on the same level. Recently, the anti-blockage systems, which prevent the vehicle to be blocked during the braking, have contributed to the decrease of the numbers of the traffic accidents. Troublye in the wheels are mostly because of the abrasion on various parts of the wheels. The abrasion in the wheels can cause the accidents through making the stopping distance longer. xvThe factors that cause the abrasion of the wheels can be summarized as follows: High speed, harsh stopping and takeoff, heat, tyre pressures, road surface and structure, and mechanical disorder. Heat is the most dangerous factor which cause the abrasion in the wheels. Moreover, the factors such as less air, overload, and high speed can make the wheels take fire because of the high temperature. If the wheel is not replaced with a new one after having extinguished it, that can cause new accidents. A trouble to occur in any part of the vehicle can affect the functions of the other parts. For example, less or much air in tyres can affect the other front parts of the vehicle. Another example is the fact that defected or old dampers cause the abrasion of the wheels. Thus, this proves the importance of the maintenance and control in vehicles, and that even a small defect should not be ignored. Consequently, the increasing number of the technical troubles in the vehicles does not mean that there will not be any traffic accident any more. Yet, the less troubles in the vehicles mean less accident in the traffic. Thus, the traffic jam shall be less, and, what is more important is the less number of loss of life and goods. We also would like to offer to use the public transportation wehicles if we have a chance to choose. Thus, the number of the traffic accidents will decrease, and we see less traffic jam. If you obey the traffic rules in a vehicle, of which maintenance and control procedure are applied, the risk of accident will be least. xvi
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