Automobile Tire

Tire are rubber and fabric devices that, when attached to the wheels of a vehicle, provide the contact between the vehicle and the road surface, tires also support the weight of the vehicle. They may be solid or pneumatic (air-filled) in structure, with the latter by far the most prevalent today. Compressed air within the tire carries 90 percent of the load, with the tire's complex structure of rubber and fabric carrying the remaining 10 percent.

ConstructionThe tread of the tire grips the road surface, and the supporting sidewalls run from tread to wheel trim. Tread patterns are especially important when the road is wet. Continuous channels from the center to the edge of the tread direct the water outward. Otherwise, water would form a wedge and cause the tire to lift off the road. This so-called aquaplaning phenomenon is one reason that smooth tire are dangerous in wet conditions. Snow tires and off-highway tires have deeper treads or separate cleats.

A tire's sidewalls flex up and down, helping cushion the vehicle from road irregularly in order to transfer loads of steering, braking, and acceleration. At their innermost edges, sidewalls meet the tire's breads (hoops of steel wire covered with hard rubber). Each bead reinforces the interface between the tire and wheel-rim and flexes the tire's inner diameter.

Reinforcing cords, which give the tire its strength, are arranged beneath the tire's surface. The three classes of modern tires can be distinguished by the direction of the cords. A bias-ply-tire, the earliest, has two or more plies of cord running across the tire at an angle, or bias, from the placed between the plies. A radial tire has reinforcing cords running hoop-fashion from bead to bead. Like a bias-belted tire, a radial has reinforcing belts under its tread, but radial belt cords are angled closer to the tire's centerline. The lack of bias sidewall reinforcement makes a radial's sidewalls more flexible. This gives the tread a better grip and longer life.

Tire construction begins with the sidewall. The different necessitated by the different requirements of each part of the tire are brought together to formed from wound and rubber-coated steel wires. Steel or synthetic-fiber fabric is rubber-coated and cut either at an angle or straight across, depending on tire type. All these materials are assembled for hand lay-up on a rotating, collapsible drum. Next, the beads and tread-sidewalls strip are added. Finally, a heated the tread pattern and vulcanized the rubber.

Speed Transmission

Manual Transmission Early transmission were all manually operated. There were two shaft, each with several gears of different sizes. One shaft could be moved or shifted, with respect to the other in order to mesh, or engage, a gear on one shaft with a gear on the other.

For most cars a transmission with three forward gears and one reverse gear is adequate. In some smaller car with small engines, four or five speed transmissions are used to compensate for the lower torque available from the engine. Truck designed to haul heavy loads may have as many as 20 forward speeds and four speeds in reverse. The part of the transmission that houses the gears is called gearbox.

A manual transmission has a clutch to disconnect the engine crankshaft from the gearbox while shifting gears. The driver shifts gear by manipulating a shift lever, which is connected to the transmission by a mechanical linkage. In the newer synchromesh transmission, synchronizers allow the gear teeth to be in constant mesh, turning freely on their shaft. The selected combination is first synchronized (the teeth on the two gears are brought to the same speed of rotation) and then locked together so that power is transmitted to ther drive shaft and then to the differential. Automatic Transmission Automatic transmissions use a torque converter – to couple the engine and the gearbox. It is a form of fluid coupling in which one rotating member indirectly imparts a rotating motion to another rotating member on another shaft that is connected to the gearbox.

Transmission

Transmission in automotive is a device for transmitting power from the engine to the drive shaft, from which it is eventually carried to the wheels. The device must convert the power from the relatively fixed high angular velocity and low torque (turning force) of the engine crankshaft to the variable, usually lower speeds and higher torques needed at the wheels. The crankshaft is the part of the engine that converts the back-and-forth (reciprocating) motion of the engine piston into rotary motion.

Generally, car transmission converts the engine power by means of a system of gears, providing a variety of gear ratios between the engine and the wheels. When the vehicle is starting from rest, the transmission is placed in first, or low, gear in order to produce a high torque at a low wheel speed. As the car speeds up, the driver shifts or the automatic transmission is shifted into a higher gear. With each higher gear, the drive shaft turn faster but with less power and torque. As an example, consider a simple three-speed transmission. When the car starts from the rest in first gear, the gear ratio might be 3 to 1, this means that the crankshaft turn three times to turn the drive shaft once. After the car gains some speed, the transmission is shifted into the second gear, with a gear ratio say, 2 : 1. After a further increase in wheel speed, a shift is made into high, or third, gear. This is also called direct drive, because there is no gear reduction in the turn at the same speed as the crankshaft.

The next article about the two basic type of transmission are the manual type and the automatic transmission pada speed transmission.

1. Input shaft from engine
2. Layshaft
3. Idler
4. Output shaft
5. Gearshift lever, locks a gear wheel on the output shaft into place

Brake (2)

Hydraulic Brake

Automobiles were originally braked mechanically. By about 1930, however, modern hydraulic system were developed. In a hydraulic system, depression of the brake pedal moves a piston in a master cylinder, forcing hydraulic fluid through piping to a slave cylinder at each wheel. These cylinders are each fitted with pistons moved by the pressure of the fluid, which brings the brake lining into contact with the rotating brake drum or disk, producing a breaking force.

As vehicle became heavier and faster, the pedal pressure required to brake the vehicle increased beyond a comfortable, safe level. In automobiles power brakes use the engine vacuum to increased the pressure applied to the piston in the master cylinder, reducing the required pedal pressure.

Power-assisted brake systems are also needed in such heavy vehicle as bases, trucks and railroad trains. One such system is the pneumatically operated Westinghouse air brake patented in 1869 by George Westinghouse, an American manufacturer. Each railroad car has its own reservoir, called an auxiliary reservoir, connected by means of a valve with a brake pipe extending the length of the train. To apply the brakes, the engineer lowers the pressure and the brake cylinder. This allows the compressed air in the reservoir to enter the brake cylinder, braking the train. To release the brakes the engineer builds up the pressure in the brake pipe. Any sudden drop in brake-pipe air pressure, such as that caused by cars uncoupling, will automatically apply the brake, making this a fail-safe system.
Other types of Brake

A machine powered by an electric motor may be designed with dynamic braking. The circuitry of the motor can be switched so that the motor operates as a generator driven by the rotating axle. This convert the rotational energy into electricity, which slows the machines.Braking can also be accomplished by reversing the thrust. In propeller-driven aircraft and ships, the pitch of the propeller blade can be reversed so as to produced thrust in the opposite direction, in some ships the direction of propeller rotation can be reversed.

Brake (1)

Brake is the very important part of your car, because it is function to stop the car and to keep safe for other driver. A brake is a device used to slow down or stop a moving object. It operate by converting the energy of motion, which is called kinetic energy, into some other form of energy, usually heat energy. A stationary part, the brake shoe, is pressed against rotating part, commonly a shaft, disk or drum, producing a large amount of friction. The brake shoe usually provided with a lining made of heat-resistance friction material, often containing asbestos. The brake shoe may be pressed against the rotating part mechanically, pneumatically, electromagnetically or hydraulically.

Block, Disk, Drum, and Band Brake 

Various types of brake distinguished. The simples types is the single block brake. The concave side of a block is pressed against the rotating part, which is usually a wheel or drum fastened to a shaft. This type of brake was used in horse drawn vehicles. Vibration of the wheel shaft can be prevented by the use of a double block brake, in which two blocks are symmetrically positioned on opposite sides of the shaft. The disk brake has a block that pressed against the flat surface of a disk rather than against the wheel rim. An example is a caliper disk brake, which was originally developed for aircraft and is now used in automobiles; the same type is used in bicycles. Two opposed blocks (brake shoes) squeeze between them like a pair of calipers. Because disk brakes are not enclosed, they allow air to flow over them, dissipating heat rapidly.

A drum brake has two curved brake shoes that press against a rotating brake drum. Automobiles drum brakes have internal brake shoes that are inside a tightly closed drum and actuated by hydraulic pressure. When drum brakes heat up, they are subject to fading, a decreased in braking effectiveness during extended use of the brake. This happen because the increased temperature causes a decreased in the friction of brake-lining material. Special lining materials with reduced fading have been developed. New cars are often equipped with disk brakes especially on the front wheels. A band brake consists of a metal band lined with a friction material that can be tightened around the rotating part. Band brakes are used mainly for hoist and excavating machinery.

Primary Batteries

Primary batteries are made today in hundreds of shapes and sizes and utilize several chemical reactions. Their development and production, however, has been a slow process. Alessandro Volta made the first battery, used flashlights, cameras and radios, was derived directly from battery developed by the French chemist George Leclanche in 1860s.

The battery in its original form had a zinc rod amalgamated with mercury as anode, a conducting mix of manganese dioxide (MnO2) and Carbon in porous pot as cathode, a central carbon rod or plate as current collector, and a saturated solution of ammonium chloride (NH4Cl) as electrolyte. The cell was assembled in a glass jar and produced about 1.5 volts. In spite of its lack of portability, it was widely used in telephones and doorbells until well into the 20th century and was an excellent example of a technical advance that became an immediate commercial success.

The modern dry cell replaced the liquid replace the liquid electrolyte with a paste consisting of a mixture of zinc chloride (ZnCl2) and NH4Cl. A zinc anode was fashioned as a cylindrical cell container, and the cathode remained MnO2 and Carbon.

In alkaline dry cell, the electrolyte is potassium hydroxide (KOH). A more recent innovation, this type of battery supplies larger currents and is used in radios, tape recorder, shavers, and hearing aids. Even higher currents are obtained when mercuric oxide (HgO) replaces the MnO2 as cathode.

Storage Battery
For many years in standard secondary (storage) system has been the lead-acid battery. Nickel-cadmium batteries have also become common. In recent years other type have been developed that are applicable to specialized demands.

The lead-acid battery was invented in 1860 by Gaston Plante. The electrolyte is sulfuric acid (H2SO4), the electrode are lead and lead dioxide (PbO2). Three or six cells are placed within a plastic or rubber container, the form seen in automobiles. Recently, small D-size batteries of this type have been introduced.

In more recent years the power demands of product such as portable recorders, calculators and implanted biochemical devices fostered a search for batteries with higher energy-to-weight ratios, more consistent voltage outputs, and longer lifetimes. Now in common use for such purposes are secondary nickel-cadmium batteries, in which cadmium serves as the negative electrode, nickel oxide (Ni2O3) as positive electrode, and KOH as the electrolyte.

Battery

A battery is a device in which the energy of a chemical reaction is converted into electricity. This is accomplished by immersing two metals in an electrolytic solution, where the electrolyte, a non metallic conductor, dissociates into charged components, or ions. The metals must be chosen according to their electrochemical activity, which depends on their ability to gain or lose electrons. This gain or loss causes a potential difference or voltage, between the two metals. When the metal are connected by an external circuit to a load such as light bulb, a current of electrons will flow from one metal (the anode), through the wire and the load, to the other metal (the cathode). Ion carry the current through the electrolyte solution and complete circuit.

In regard to electron current moving through the wire and load, the anode is negative the cathode positive. In regard to the ion current, the anode is positive and the cathode negative, since the positive ion coat the anode and make it appear positive. It is standard to table the electrodes in regard to the electron current. In either case, the anode is the metal that give up electrons to the wire and positive ions to the solution, and the cathode accept electrons from the wire and positive ions from the solution.

Battery differ from fuel cell in that they contain all the chemicals to be used in the reaction, fuel cells are supplied with these reactants from an outside source. A battery in which the reactions are not readily reversible is called a primary battery. If they can be reversed by the passage of current in the opposite direction, the battery is called a secondary, or storage, battery. Although, theoretically, many combination of electrochemical reactions are possible in primary batteries, only a few have been successfully realized, and fewer yet are sufficiently reversible for satisfactory secondary cell.

The simple cell has a lead anode (+) and a lead dioxide cathode (-), immersed in sulfuric acid. As current flow through the wire from anode to cathode, it light the bulb. A cell in storage battery has several positive and negative plate, separated porous insulators.

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