Carburetor

 

 Carburetor introduction

carburetter  is a device that blends air and fuel for an internal combustion. It is sometimes colloquially shortened to carb in North America or carby in Australia.^[1] To carburate or carburet (and thus carburation or carburetion, respectively) is to blend the air and fuel or to equip (an engine) with a carburetor for that purpose.
Carburetors have largely been supplanted in the automotive industry by fuel injection. They are still common on small engines for lawn mowers, rototillers, and other equipment.



 How does carburetor works ?

Engines are mechanical things, but they're chemical things too: they're designed around a chemical reaction called combustion: when you burn fuel in air, you release heat energy and produce carbon dioxide and water as waste products. To burn fuel efficiently, you have to use plenty of air. That applies just as much to a car engine as to a candle, an outdoor campfire, or a coal or wood fire in someone's home.
Photo: A candle mixes wax fuel with air from its surroundings. With too little air, the flame goes out; with too much, the flame will roar and burn blue. A car engine burns fuel in a similar way. Getting its air supply just right is more tricky—and more critical.
With a campfire, you never really have to worry about having too much or too little air. With fires burning indoors, air is in shorter supply and far more important. Having too little oxygen will cause an indoor fire (or even a fuel-burning device like a gas central-heating furnace (boiler)) to produce dangerous air pollution, including toxic carbon monoxide gas. With a car engine, having too much air is just as bad as having too little. Too much air and not enough fuel means an engine burns "lean," while having too much fuel and not enough air is called burning "rich"; both are bad for the engine in different ways.

Brake system

Brakes

The brake system is often forgotten when it comes to vehicle maintenance, but as the first step toward vehicle safety, the brake system should be prioritized. Not only will proper maintenance prevent a complete brake system failure, it will also save you money by preventing premature corrosion of internal parts and equipment breakdown. Always use the brake fluid type designated on the brake reservoir cap or in the owner’s manual.
Brake System
A necessary step in brake system maintenance is changing the brake fluid. Brake fluid is hygroscopic (it absorbs water). Replacing used fluid with fresh fluid keeps the system free of moisture. If your brakes seem to not work as well as they used to in severe stopping conditions, flushing the brake fluid and adding fresh fluid can restore braking performance.
How to Check the Brake Fluid Level:
1. Find the brake fluid reservoir — it’s under the hood toward the rear of the engine bay on the driver’s side.
2. Clean the reservoir and its cap of any road grime and dust.
3. Remove the cap and add fluid until the level reaches the “full” or “max” mark on the side of the reservoir.
4. Replace the cap.

Main Components of the Braking System

• Brake Pedal
• Brake Booster
• Master Cylinder
• Brake Fluid
• Hydraulic Lines
• Proportional Valve
• Hydraulic Calipers
• Disc Brakes
• Brake Pads
• Rotor
• Drum Brakes
• Drum
• Brake Shoes
• Wheel Cylinder
• Antilock Braking System (ABS)
• Electronic Wheel Sensors
• Emergency Brake

How does the Braking System work?

The brake pedal, on which you apply pressure to slow down or stop your vehicle, is connected by levers and rods to the brake booster. The brake booster multiplies and transfers the leverage force produced by stepping on the brake pedal to the master cylinder.  In turn, the master cylinder uses that amplified leverage to pressure the brake fluid from its reservoir through hydraulic lines toward the two front and rear brakes that are mounted on the wheels of the vehicle.

 

Antilock Braking System (ABS)

The Antilock Braking System is located between the brake master cylinder and the wheels. Its purpose is to prevent instability of the vehicle under extreme braking conditions. To do so, the ABS modulates the pressure of the brake fluid that is applied to each front and rear brake, preventing the wheels from “locking up” - as could be the case in a conventional Braking System (see above). Normal brake fluid pressure is restored when there is no longer a possibility of the wheels locking up. As you drive, the system constantly monitors each wheel through an electronic wheel sensor: if one of the wheels is turning slower than the others, the antilock system releases the pressure on that wheel. In the eventuality of an ABS failure, the ABS warning light comes “on” on the instrument panel: it indicates that the basic braking system applies MAXIMUM pressure on all the wheels WHICH CAN LEAD TO SERIOUS SAFETY CONCERNS.

Moreover, if your vehicle is equipped with an Antilock Braking System, the pads (of disk brakes) and shoes (of drum brakes) are fitted with wear sensors that indicate any wearing of these parts.

Emergency Brake

Every vehicle is equipped with an emergency braking system that is independent from the main system.  The emergency brake expands the brake shoes on the drums (for rear brake drums) or compresses the rear brake rotors (for rear disc brakes) by means of a mechanical device.

Fuel System

The fuel system is made up of the fuel tank, pump, filter, and injectors or carburetor, and is responsible for delivering fuel to the engine as needed. Each component must perform flawlessly to achieve expected vehicle performance and reliability.

FUEL TANK

Tank location and design are always a compromise with available space. Most automobileshave a single tank located in the rear of the vehicle. Fuel tanks today have internalbaffles to prevent the fuel from sloshing back and forth. If you hear noises from the rearon acceleration and deceleration the baffles could be broken. All tanks have a fuel fillerpipe, a fuel outlet line to the engine and a vent system. All catalytic converter cars areequipped with a filler pipe restrictor so that leaded fuel, which is dispensed from athicker nozzle, cannot be introduced into the fuel system. All fuel tanks must be vented.Before 1970, fuel tanks were vented to the atmosphere, emitting hydrocarbon emissions.Since 1970 all tanks are vented through a charcoal canister, into the engine to be burnedbefore being released to the atmosphere. This is called evaporative emission control andwill be discussed further in the emission control section. Federal law requires that all1976 and newer cars have vehicle rollover protection devices to prevent fuel spills.

FUEL LINES

Steel lines and flexible hoses carry the fuel from the tank to the engine. Whenservicing or replacing the steel lines, copper or aluminum must never be used. Steel linesmust be replaced with steel. When replacing flexible rubber hoses, proper hose must beused. Ordinary rubber such as used in vacuum or water hose will soften and deteriorate. Becareful to route all hoses away from the exhaust system.

FUEL PUMPS

Two types of fuel pumps are used in automobiles; mechanical and electric. All fuelinjected cars today use electric fuel pumps, while most carbureted cars use mechanicalfuel pumps. Mechanical fuel pumps are diaphragm pumps, mounted on the engine and operatedby an eccentric cam usually on the camshaft. A rocker arm attached to the eccentric movesup and down flexing the diaphragm and pumping the fuel to the engine. Because electricpumps do not depend on an eccentric for operation, they can be located anywhere on thevehicle. In fact they work best when located near the fuel tank.
Many cars today, locate the fuel pump inside the fuel tank. While mechanical pumpsoperate on pressures of 4-6 psi (pounds per square inch), electric pumps can operate onpressures of 30-40 psi. Current is supplied to the pump immediately when the key isturned. This allows for constant pressure on the system for immediate starting. Electricfuel pumps can be either low pressure or high pressure. These pumps look identical, so becareful when replacing a fuel pump that the proper one is used. Fuel pumps are rated bypressure and volume. When checking fuel pump operation, both specifications must bechecked and met.

FUEL FILTERS

The fuel filter is the key to a properly functioning fuel delivery system. This is moretrue with fuel injection than with carbureted cars. Fuel injectors are more susceptible todamage from dirt because of their close tolerances, but also fuel injected cars useelectric fuel pumps. When the filter clogs, the electric fuel pump works so hard to pushpast the filter, that it burns itself up. Most cars use two filters. One inside the gastank and one in a line to the fuel injectors or carburetor. Unless some severe and unusualcondition occurs to cause a large amount of dirt to enter the gas tank, it is onlynecessary to replace the filter in the line.

Air filter

Air filter :

A particulate air filter is a device composed of fibrous materials which removes solid particulates such as dust, pollen, mould, and bacteria from the air. A chemical air filter consists of an absorbent or catalyst for the removal of airborne molecular contaminants such as volatile organic compounds or ozone. Air filters are used in applications where air quality is important, notably in building ventilation systems and in engines.
Some buildings, as well as aircraft and other human-made environments (e.g., satellites and space shuttles) use foam, pleated paper, or spun fiberglass filter elements. Another method, air ionisers, use fibers or elements with a static electric charge, which attract dust particles. The air intakes of internal combustion engines and air compressors tend to use either paper, foam, or cotton filters. Oil bath filters have fallen out of favor. The technology of air intake filters of gas turbines has improved significantly in recent years, due to improvements in the aerodynamics and fluid dynamics of the air-compressor part of the gas turbines.

Paper air filter

Filters made of paper offer filtration and air flow.  They are generally cheaper, but have to be replaced every 5,000 to 10,000 miles. 

Gauze Air Filters

Gauze air filters

Gauze style air filters offer filtration and air flow. There are 2 types: oil based and dry gauze filters. The biggest advantage of a gauze style air filter is that they're designed to last the life of the vehicle. However, this requires you to regularly clean the air filter with the manufacturer's recommended air filter cleaning kit. Oil based gauze filters tend to filter better then dry but have to be oiled. Whereas, dry gauze filters don’t need to be oiled, but the filtration generally isn’t the best. Each air filter manufacturer makes their gauze filters differently. Most have between four and seven layers of gauze depending on the brand and style of filter.

Foam Air Filters

Foam air filters

Foam air filters are gaining in popularity and offer both filtration and air flow. Foam filters are very successful in dirt track racing because of their ability to filter dirt while maintaining air flow. These foam style air filters are designed to last the life of the vehicle, provided you follow the manufacturer's cleaning instructions. These filters need to be oiled, just like oil based gauze filters.

How air filter works 

 

 

Engine Tune up

 Engine Tune up

Engine tuning is an adjustment, modification of the internal combustion engine or modification to its control unit, otherwise known as its ECU (Engine Control Unit). It is performed to yield optimal performance, to increase an engine's power output, economy, or durability. These goals may be mutually exclusive, and an engine may be detuned with respect to output (work) in exchange for better economy or longer engine life due to lessened stress on engine components.



there are two types of engine tune up

    1 Minor tune up
     2 Major tune up

     Minor tune up

Minor Tuneup — Electrical

The electrical components replaced in a minor tuneup usually consist of spark plugs only. The new spark plugs are gapped to manufacturer's specifications and installed in the vehicle. As a rudimentary inspection, the mechanic will check the timing, and make visual inspections of the air filter, cap, rotor and plug wires. Depending upon the shop practice, older vehicles might receive the installation of points and condenser as part of a minor tuneup. Some manufactures claim that their vehicles do not require a spark plug change until after 100,000 miles.

Minor Tuneup — Oil, Grease and Fluids

• An oil change (with filter), on rare occasions, can be added to a minor tuneup, as well as a suspension lubrication. If the minor tuneup falls within a period of time that permits an oil change, filter change and lubrication, then it can be included on the service ticket. Ordinarily, vehicles receive oil changes as frequently as every 3,000 to 10,000 miles, and many vehicle owners perform their own oil and filter changes. All fluid levels, including transmission, power steering, radiator and brake fluids receive visual checks, and get a topping-off if the reservoir requires less than a quart.
  
  
  
  
   

Major Tune up

Major Tuneup — Electrical

• A major tuneup for electrical components consists of the replacement of all spark plugs, spark plug wires, distributor cap, rotor, and points and condenser, if applicable for an older vehicle. The mechanic will check the timing and adjust it to specifications. Sometimes a voltage check is performed on the charging system, as well as a battery check for proper electrolyte level. All electrical vacuum switching valves and electrical sensors receive a visual inspection.

Major Tuneup — Fuel Systems

• Fuel systems in a major tuneup include the changing of the main fuel filter, and sometimes the in-line carburetor fuel filter or screen. The mechanic will adjust a carburetor-type vehicle, setting the idle mixture screws, idle speed, fast idle or choke. Some repair facilities add a fuel system cleaning for fuel injected-engines, which most often entails an additive.

Major Tuneup — Oil, Grease and Fluids

• A major tune up will include an oil and filter change, as well as a complete suspension and drive line grease lubrication. A mechanic will check the CV (constant velocity) joint boots and other suspension components. The rear-end differential oil will be checked and filled to capacity, as well as any gear oil needed for a manual transmission. Another fluid might involve the windshield washer soap and water. The difference in the major versus the minor tuneup, as far as fluids, will be that the cost of fluid additions in the major tuneup will be absorbed into the cost.

Major Tuneup Optional Services

• Some optional services occur when the repair facility includes them in their major tuneup. Not all repair facilities include extra service procedures. Some major tuneup additions you might see will be the checking and filling of tires, a brake inspection and brake adjustment. A solid lifter valve adjustment will most likely appear on a major tuneup ticket, since it is acknowledged as a major tuneup item. There could be a shop that charges extra for a valve adjustment, depending upon the model and complexity of the job.

Cooling system

Engine cooling

A cooling system in an internal combustion engine that is used to maintain the various engine components at temperatures conducive to long life and proper functioning. Gas temperatures in the cylinders may reach 4500°F (2500°C). This is well above the melting point of the engine parts in contact with the gases; therefore it is necessary to control the temperature of the parts, or they will become too weak to carry the stresses resulting from gas pressure. The lubricating oil film on the cylinder wall can fail because of chemical changes at wall temperatures above about 400°F (200°C). Complete loss of power may take place if some spot in the combustion space becomes sufficiently heated to ignite the charge prematurely on the compression stroke. See Internal combustion engine

A thin protective boundary of relatively stagnant gas of poor heat conductivity exists on the inner surfaces of the combustion space. If the outer cylinder surface is placed in contact with a cool fluid such as air or water and there is sufficient contact area to cause a rapid heat flow, the resulting drop in temperature produced by the heat flow in the inside boundary layer keeps the temperature of the cylinder wall much closer to the temperature of the coolant than to the temperature of the combustion gas.

If the coolant is water, it is usually circulated by a pump through jackets surrounding the cylinders and cylinder heads. The water is circulated fast enough to remove steam bubbles that may form over local hot spots and to limit the water's temperature rise through the engine to about 15°F (8°C). In most engines in automotive and industrial service, the warmed coolant is piped to an air-cooled heat exchanger called a radiator (see illustration). The airflow required to remove the heat from the radiator is supplied by an electric or engine-driven fan; in automotive applications the airflow is also supplied by the forward motion of the vehicle. The engine and radiator may be separated and each placed in the optimum location, being connected through piping. To prevent freezing, the water coolant is usually mixed with ethylene glycol.

Types of transmisssion system

   there are two types of trasnmission system
          
              1: Manual transmission
              2:  Automatic transmission
  

                1 Manual transmission

     

Manual transmissions come in two basic types:

• A simple but rugged sliding-mesh or unsynchronized/non-synchronous system, where straight-cut spur gear sets spin freely, and must be synchronized by the operator matching engine revs to road speed, to avoid noisy and damaging clashing of the gears
• The now common constant-mesh gearboxes, which can include non-synchronised, or synchronized/synchromesh systems, where typically diagonal cut helical (or sometimes either straight-cut, or double-helical) gear sets are constantly "meshed" together, and a dog clutch is used for changing gears. On synchromesh boxes, friction cones or "synchro-rings" are used in addition to the dog clutch to closely match the rotational speeds of the two sides of the (declutched) transmission before making a full mechanical engagement.

The former type was standard in many vintage cars (alongside e.g. epicyclic and multi-clutch systems) before the development of constant-mesh manuals and hydraulic-epicyclic automatics, older heavy-duty trucks, and can still be found in use in some agricultural equipment. The latter is the modern standard for on- and off-road transport manual and semi-automatic transmission, although it may be found in many forms; e.g., non-synchronised straight-cut in racetrack or super-heavy-duty applications, non-synchro helical in the majority of heavy trucks and motorcycles and in certain classic cars (e.g. the Fiat 500), and partly or fully synchronised helical in almost all modern manual-shift passenger cars and light trucks.

             2 Automatic transmission  : 

Automatic transmissions are easy to use. However, in the past, automatic transmissions of this type have had a number of problems; they were complex and expensive, sometimes had reliability problems (which sometimes caused more expenses in repair), have often been less fuel-efficient than their manual counterparts (due to "slippage" in the torque converter), and their shift time was slower than a manual making them uncompetitive for racing. With the advancement of modern automatic transmissions this has changed.^{[citation needed]}
Attempts to improve fuel efficiency of automatic transmissions include the use of torque converters that lock up beyond a certain speed or in higher gear ratios, eliminating power loss, and overdrive gears that automatically actuate above certain speeds. In older transmissions, both technologies could be intrusive, when conditions are such that they repeatedly cut in and out as speed and such load factors as grade or wind vary slightly. Current computerized transmissions possess complex programming that both maximizes fuel efficiency and eliminates intrusiveness. This is due mainly to electronic rather than mechanical advances, though improvements in CVT technology and the use of automatic clutches have also helped. A few cars, including the 2013 Subaru Impreza^[10] and the 2012 model of the Honda Jazz sold in the UK, actually claim marginally better fuel consumption for the CVT version than the manual version.
For certain applications, the slippage inherent in automatic transmissions can be advantageous. For instance, in drag racing, the automatic transmission allows the car to stop with the engine at a high rpm (the "stall speed") to allow for a very quick launch when the brakes are released. In fact, a common modification is to increase the stall speed of the transmission. This is even more advantageous for turbocharged engines, where the turbocharger must be kept spinning at high rpm by a large flow of exhaust to maintain the boost pressure and eliminate the turbo lag that occurs when the throttle suddenly opens on an idling engine.