AUTOMOBILE LUBRICATION SYSTEM

The lubrication system of an automobile is mostly used for collecting, cleaning, cooling and re circulating oil in the engine of vehicle. The main function an automobile lubrication system is to circulate and deliver oil to all the moving parts of an engine in order to lessen friction between surfaces that comes in contact with each other. The lubrication system of an automobile acts to reduce engine wear caused by the friction of its metal parts, as well as to carry off heat

Automotive Fluids and Greases refer to materials be it a gas, vapor, or liquids used for keeping various parts of automobile in a good working condition while automobile greases are the thickened gels made up of natural, synthetic and semi synthetic substances. The automotive greases are mainly used for lubricating and sealing various parts of a vehicle such as bearings, combustion engines, compressors, piston pumps and gears.

Various types of automotive fluids and greases are:
Brake Fluid
Grease Nipple
Transmission Fluid

Gear Grease
Lube Grease
Power steering Fluid

BRAKE FLUIDS

Brake fluids must have certain characteristics and meet certain quality standards for the braking system to work properly.

Boiling point

Brake fluid is subjected to very high temperatures, especially in the wheel cylinders of drum brakes and disk brake calipers. It must have a high boiling point to avoid vaporizing in the lines. This vaporization is a problem because vapor released in to the lines is compressible and would result in an inability of the hydraulic fluid to transfer braking force. Quality standards refer to a brake fluid's "dry" and "wet" boiling points. Wet boiling point, which is usually much lower, refers to the fluid's boiling point after absorbing a certain amount of moisture. This is several percent, varying from formulation to formulation ; in higher levels the moisture itself can boil separately from the base fluid. Glycol-ether brake fluids are hygroscopic (water loving), which means they absorb moisture from the atmosphere under normal humidity levels. More modern fluids (e.g. silicone-based formulations) can maintain an acceptable boiling point as they absorb moisture over the fluid's service life.

Viscosity

For reliable, consistent brake system operation, brake fluid must maintain a constant viscosity under a wide range of temperatures, including extreme cold. This is especially important in systems with Antilock brakes (ABS), Traction Control, and Stability Control.

Corrosion

Brakes fluids must not corrode the metals used inside components such as calipers, master cylinders, etc. They must also protect against corrosion as moisture enters the system. Additives (corrosion inhibitors) are added to the base fluid to accomplish this.

Compressibility

Brake fluids must maintain low level of compressibility that remains low, even with varying temperatures.

Service and maintenance

Most automotive professionals agree that brake fluid should be flushed, or changed, every 1-2 years.[1] Many manufacturers also require periodic fluid changes to ensure reliability and safety. Once installed, moisture diffuses into the fluid through brake hoses and rubber seals and eventually the fluid will have to be replaced when the water content becomes too high. Electronic testers and test strips are commercially available to measure moisture content. The corrosion inhibitors also degrade over time. New fluid should always be stored in a sealed container to avoid moisture intrusion.

Brake fluid is not considered a "top up" fluid. If it is low, there is usually a problem. Brake fluid level in the master cylinder will drop as the linings (pads or shoes) wear and the calipers or wheel cylinders extend further to compensate. Brake fluid level may also be low because of a leak, which could result in a loss of hydraulic pressure and consequently, a loss of braking ability. As a general rule, brake fluids with different DOT ratings should not be mixed.

Brake fluid can be dangerous as it is toxic and highly flammable. It will also lift or strip paints and other coatings on contact.

Components

===Mineral-based=== (DOT 3,4,5.1)

* Alkyl ester
* Aliphatic amine
* Diethylene glycol
* Diethylene glycol monoethyl ether
* Diethylene glycol monomethyl ether
* Dimethyl dipropylene glycol
* Polyethylene glycol monobutyl ether
* Polyethylene glycol monomethyl ether
* Polyethylene oxide
* Triethylene glycol monobutyl ether
* Triethylene glycol monoethyl ether
* Triethylene glycol monomethyl ether

===Silicone-based=== (DOT 5)

* Di-2-ethylhexyl sebacate
* Dimethyl polysiloxane
* Tributyl phosphate

WHAT IS DOT 3?

DOT 3 is one of several designations of automotive brake fluid, denoting a particular mixture of chemicals imparting specified ranges of boiling point.

In the United States, all brake fluids must meet Standard No. 116; Motor vehicle brake fluids[1]. Under this standard there are three Department of Transportation (DOT) minimal specifications for brake fluid. They are DOT 3, DOT 4, and DOT 5.1.

DOT 3, like DOT 4 and DOT 5.1, is a polyethylene glycol-based fluid (contrasted with DOT 5, which is silicone-based). Fluids such as DOT 3 are hygroscopic and will absorb water from the atmosphere. This degrades the fluid's performance, and if allowed to accumulate over a period of time, can drastically reduce its boiling point. In a passenger car this is not much of an issue[citation needed], but can be of serious concern in racecars or motorcycles[citation needed].

As of 2006[update], most cars produced in the U.S. use DOT 3 brake fluid.

Boiling points

Minimal boiling points for these specifications are as follows (wet boiling point defined as 3.7% water by volume):

Dry boiling point Wet boiling point
DOT 3 205°C (401°F) 140°C (284°F)
DOT 4 230°C (446°F) 155°C (311°F)
DOT 5 260°C (500°F) 180°C (356°F)
DOT 5.1 270°C (518°F) 191°C (375°F)

DOT 4

DOT 4 is one of several designations of automotive brake fluid, denoting a particular mixture of chemicals imparting specified ranges of boiling point.

In the United States, all brake fluids must meet Standard No. 116; Motor vehicle brake fluids[1]. Under this standard there are three Department of Transportation (DOT) minimal specifications for brake fluid. They are DOT 3, DOT 4, and DOT 5.1.

DOT 4, like DOT 3 and DOT 5.1, is a polyethylene glycol-based fluid (contrasted with DOT 5 which is silicone-based). Fluids such as DOT 4 are hygroscopic and will absorb water from the atmosphere. This degrades the fluid's performance, and if allowed to accumulate over a period of time, can drastically reduce its boiling point. In a passenger car this is not much of an issue[citation needed], but can be of serious concerns in racecars or motorcycles[citation needed].

One particular brand of DOT 4 brake fluid lists the following ingredients on its MSDS:
Chemical CAS no Percent
Triethylene glycol 000112-27-6 5-25
Tetraethylene glycol 000112-60-7 5-25
Dibutoxy tetraglycol 000112-98-1 10-50
Tetraethylene glycol diethyl ether 004353-28-0 10-50
Propane, 2-methoxy-1-(2-methoxy-1-methylethoxy)- 089399-28-0 10-50

HOW TO CHECK BRAKE FLUID

* Hand Soaps
* Brake Fluids
* Car Manuals

Step1
Find the brake master cylinder. This is usually located under the hood on the driver's side of the car, toward the back of the engine compartment. Imagine where your brake pedal would end up if it went all the way through to the engine. The brake master cylinder is a small (about 6-by-2 inches), rectangular piece of metal with a plastic reservoir and a rubber cap on top, and small metal tubes leading from it.
Step2
Check your manual if you aren't sure that you've found the master cylinder. The rubber cap will usually read "use only DOT 3 or 4 brake fluid from a sealed container."
Step3
Note that on most newer cars the reservoir is translucent and you can see the fluid level without removing the cap. There will be a "full" line, the brake fluid should be at this line.
Step4
In older cars (pre-1980) the brake master cylinder reservoir may be made entirely of metal so that you must take the top off to check the fluid level. The top is held on by a metal clamp, use a screwdriver to pop off the clamp and lift the lid.
Step5
Add brake fluid to the "full" line. Use the correct brake fluid for your car: Check the rubber cap and your owner's manual to find out what grade of brake fluid your car requires. Most cars use DOT (Department of Transportation) 3 or 4. If the reservoir has 2 parts, fill both halves.


TIPS AND WARNINGS

* If the brake master cylinder is empty, the brake pedal will go to the floor. If this is the case, you will have to bleed the brakes in addition to adding fluid: Time to see your mechanic, who will flush and refill the braking system.
* Brake fluid is very toxic. Keep it away from hands and eyes, and avoid spilling it on the ground. Dispose of empty containers carefully. Be especially careful not to spill brake fluid on your car's paint.
* Wash your hands well after handling brake fluid.
* Don't drive a car that has run out of brake fluid until bleeding the brakes.

TRANSMISSION SYSTEM

Automotive basics

The need for a transmission in an automobile is a consequence of the characteristics of the internal combustion engine. Engines typically operate over a range of 600 to about 7000 revolutions per minute (though this varies, and is typically less for diesel engines), while the car's wheels rotate between 0 rpm and around 1800 rpm.

Furthermore, the engine provides its highest torque outputs approximately in the middle of its range, while often the greatest torque is required when the vehicle is moving from rest or traveling slowly. Therefore, a system that transforms the engine's output so that it can supply high torque at low speeds, but also operate at highway speeds with the motor still operating within its limits, is required. Transmissions perform this transformation.

Most transmissions and gears used in automotive and truck applications are contained in a cast iron case, though sometimes aluminium is used for lower weight. There are three shafts: a mainshaft, a countershaft, and an idler shaft.

The mainshaft extends outside the case in both directions: the input shaft towards the engine, and the output shaft towards the rear axle (on rear wheel drive cars- front wheel drives generally have the engine and transmission mounted transversely, the differential being part of the transmission assembly.) The shaft is suspended by the main bearings, and is split towards the input end. At the point of the split, a pilot bearing holds the shafts together. The gears and clutches ride on the mainshaft, the gears being free to turn relative to the mainshaft except when engaged by the clutches.

Types of automobile transmissions include manual, automatic or semi-automatic transmiss

Manual transmission

Manual transmission come in two basic types:

* a simple but rugged sliding-mesh or unsynchronized / non-synchronous system, where straight-cut spur gear sets are spinning freely, and must be synchronized by the operator matching engine revs to road speed, to avoid noisy and damaging "gear clash",
* and the now common constant-mesh gearboxes which can include non-synchronised, or synchronized / synchromesh systems, where diagonal cut helical (and sometimes 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.

The former type is commonly found in many forms of racing cars, older heavy-duty trucks, and some agricultural equipment.

Manual transmissions dominate the car market outside of North America. They are cheaper, lighter, usually give better performance, and fuel efficiency (although the latest sophisticated automatic transmissions may yield results slightly better than the ones yielded by manual transmissions). It is customary for new drivers to learn, and be tested, on a car with a manual gear change. In Malaysia, Denmark and Poland all cars used for testing (and because of that, virtually all those used for instruction as well) have a manual transmission. In Japan, the Philippines, Germany, Israel, the Netherlands, Belgium, New Zealand, Austria, the UK [3][4], Ireland[4], Sweden, France, Switzerland, Australia, Finland and Lithuania , a test pass using an automatic car does not entitle the driver to use a manual car on the public road; a test with a manual car is required.[citation needed] Manual transmissions are much more common than automatic transmissions in Asia, Africa, South America and Europe.

Non-synchronous transmissions

There are commercial applications engineered with designs taking into account that the gear shifting will be done by an experienced operator. They are a manual transmission, but are known as non-synchronized transmissions. Dependent on country of operation, many local, regional, and national laws govern the operation of these types of vehicles (see Commercial Driver's License). This class may include commercial, military, agricultural, or engineering vehicles. Some of these may use combinations of types for multi-purpose functions. An example would be a PTO, or power-take-off gear. The non-synchronous transmission type requires an understanding of gear range, torque, engine power, and multi-functional clutch and shifter functions. Also see Double-clutching, and Clutch-brake sections of the main article at non-synchronous transmissions.

Main article: Automatic transmission
Epicyclic gearing or planetary gearing as used in an automatic transmission.

Most modern North American, and many larger, high specification German cars have an automatic transmission that will select an appropriate gear ratio without any operator intervention. They primarily use hydraulics to select gears, depending on pressure exerted by fluid within the transmission assembly. Rather than using a clutch to engage the transmission, a fluid flywheel, or torque converter is placed in between the engine and transmission. It is possible for the driver to control the number of gears in use or select reverse, though precise control of which gear is in use may or may not be possible.

Automatic transmissions are easy to use. 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]

Since their inception, automatic transmissions have been very popular in the United States, and some vehicles are not available with manual gearboxes anymore. In Europe automatic transmissions are gaining popularity as well.[citation needed]

Attempts to improve the fuel efficiency of automatic transmissions include the use of torque converters which lock up beyond a certain speed, or in the higher gear ratios, eliminating power loss, and overdrive gears which automatically actuate above certain speeds; in older transmissions both technologies could sometimes become 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 very complex programming to both maximize fuel efficiency and eliminate any intrusiveness.[citation needed]

For certain applications, the slippage inherent in automatic transmissions can be advantageous; for instance, in drag racing, the automatic transmission allows the car to be stopped 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 needs to be kept spinning at high rpm by a large flow of exhaust in order to keep the boost pressure up and eliminate the turbo lag that occurs when the engine is idling and the throttle is suddenly opened.

Semi-automatic transmission

The creation of computer control also allowed for a sort of cross-breed transmission where the car handles manipulation of the clutch automatically, but the driver can still select the gear manually if desired. This is sometimes called a "clutchless manual," "dual-clutch," or "automated manual" transmission. Many of these transmissions allow the driver to give full control to the computer. They are generally designed using manual transmission "internals", and when used in passenger cars, have synchromesh operated helical constant mesh gear sets.

Specific type of this transmission includes: Easytronic, Geartronic, and Direct-Shift Gearbox.

There are also sequential transmissions which use the rotation of a drum to switch gears.

Bicycle gearing
Shimano XT rear derailleur on a mountain bike
Main articles: Bicycle gearing, Derailleur gears, and Hub gear

Bicycles usually have a system for selecting different gear ratios. There are two main types: derailleur gears and hub gears. The derailleur type is the most common, and the most visible, using sprocket gears. Typically there are several gears available on the rear sprocket assembly, attached to the rear wheel. A few more sprockets are usually added to the front assembly as well. Multiplying the number of sprocket gears in front by the number to the rear gives the number of gear ratios, often called "speeds".

Hub gears use epicyclic gearing and are enclosed within the axle of the rear wheel. Because of the small space, they typically offer fewer different speeds, although at least one has reached 14 gear ratios.[5]

Causes for failure of bicycle gearing include: worn teeth, damage caused by a faulty chain, damage due to thermal expansion, broken teeth due to excessive pedaling force, interference by foreign objects, and loss of lubrication due to negligence.

Uncommon types

Main article: Continuously variable transmission

The Continuously Variable Transmission (CVT) is a transmission in which the ratio of the rotational speeds of two shafts, as the input shaft and output shaft of a vehicle or other machine, can be varied continuously within a given range, providing an infinite number of possible ratios.

The continuously variable transmission (CVT) should not be confused with the Infinitely Variable Transmission (IVT) (See below).

The other mechanical transmissions described above only allow a few different gear ratios to be selected, but this type of transmission essentially has an infinite number of ratios available within a finite range. The continuously variable transmission allows the relationship between the speed of the engine and the speed of the wheels to be selected within a continuous range. This can provide even better fuel economy if the engine is constantly running at a single speed. The transmission is in theory capable of a better user experience, without the rise and fall in speed of an engine, and the jerk felt when changing gears.

Infinitely variable

The IVT is a specific type of CVT that has an infinite range of input/output ratios in addition to its infinite number of possible ratios; this qualification for the IVT implies that its range of ratios includes a zero output/input ratio that can be continuously approached from a defined 'higher' ratio. A zero output implies an infinite input, which can be continuously approached from a given finite input value with an IVT. [Note: remember that so-called 'low' gears are a reference to low ratios of output/input, which have high input/output ratios that are taken to the extreme with IVT's, resulting in a 'neutral', or non-driving 'low' gear limit.]

Most (if not all) IVT's result from the combination of a CVT with an epicyclic gear system (which is also known as a planetary gear system) that facilitates the subtraction of one speed from another speed within the set of input and planetary gear rotations. This subtraction only needs to result in a continuous range of values that includes a zero output; the maximum output/input ratio can be arbitrarily chosen from infinite practical possibilities through selection of extraneous input or output gear, pulley or sprocket sizes without affecting the zero output or the continuity of the whole system. Importantly, the IVT is distinguished as being 'infinite' in its ratio of high gear to low gear within its range; high gear is infinite times higher than low gear. The IVT is always engaged, even during its zero output adjustment.

The term 'infinitely variable transmission' does not imply reverse direction, disengagement, automatic operation, or any other quality except ratio selectability within a continuous range of input/output ratios from a defined minimum to an undefined, 'infinite' maximum. This means continuous range from a defined output/input to zero output/input ratio.

Electric variable

The Electric Variable Transmission(EVT) is a transmission that achieves CVT action and in addition can use separate power inputs to produce one output. An EVT usually is executed in design with an epicyclic differential gear system (which is also known as a planetary gear system). The epicyclic differential gearing performs a "power-split" function, directly connecting a portion of the mechanical power directly through the transmission and splitting off a portion for subsequent conversion to electrical power via a motor/generator. Hence, the EVT is called a Power Split Transmission (PST) by some.

The directly connected portion of the power travelling through the EVT is referred to as the "mechanical path". The remaining power travels down the EVT's "electrical path". That power may be recombined at the output of the transmission or stored for later, more opportune use via a second motor/generator (and energy storage device) connected to the transmission output.

The pair of motor/generators forms an Electric Transmission in its own right, but at a lower capacity, than the EVT it is contained within. Generally the Electric Transmission capacity within the EVT is a quarter to a half of the capacity of the EVT. Good reasons to use an EVT instead of an equivalently-sized Electrical transmission is that the mechanical path of the EVT is more compact and efficient than the electrical path.

The EVT is the essential method for transmitting power in some hybrid vehicles, enabling an Internal Combustion Engine (ICE) to be used in conjunction with motor/generators for vehicle propulsion, and having the ability to control the portion of the mechanical power used directly for propelling the vehicle and the portion of mechanical power that is converted to electric power and recombined to drive the vehicle.

The EVT and power sources are controlled to provide a balance between the power sources that increases vehicle fuel economy while providing advantageous performance when needed. The EVT may also be used to provide electrically generated power to charge large storage batteries for subsequent electric motor propulsion as needed, or to convert vehicle kinetic energy to electricity through 'regenerative braking' during deceleration. Various configurations of power generation, usage and balance can be implemented with a EVT, enabling great flexibility in propelling hybrid vehicles.

The Toyota single mode hybrid and General Motor 2 Mode hybrid are production systems that use EVTs. The Toyota system is in the Prius, Highlander, and Lexus RX400h and GS450h models. The GM system is the Allison Bus hybrid powertrains and are in the Tahoe and Yukon models. The Toyota system uses one power-split epicyclic differential gearing system over all driving conditions and is sized with an electrical path rated at approximately half the capacity of the EVT. The GM system uses two different EVT ranges: one designed for lower speeds with greater mechnical advantage, and one designed for higher speeds, and the electrical path is rated at approximately a quarter of the capacity of the EVT. Other arrangements are possible and applications of EVT's are growing rapidly in number and variety.

EVT's are capable of continuously modulating output/input speed ratios like mechanical CVT's, but offer the distinct difference and benefit of being able to also apportion power from two different sources to one output.

Hydrostatic

Hydrostatic transmissions transmit all power hydraulically, using the components of hydraulic machinery. There is no solid coupling of the input and output. One half of the transmission is a hydraulic pump and the other half is a hydraulic motor, or hydraulic cylinder. Hydrostatic drive systems are used on excavators, lawn tractors, forklifts, winch drive systems, heavy lift equipment, agricultural machinery, etc.

Hydraulic drive systems can be used as an extra transmission between motor and f.i. wheels.

Hydrodynamic

If the hydraulic pump and/or hydraulic motor are not hydrostatic, but hydrodynamic, then the transmission can be called hydrodynamic. The pump and motor can consist of rotating vanes without seals. The pump and motor can be placed in reasonable proximity. The transmission ratio can be made to vary by means of additional rotating vanes, an effect similar to varying the pitch of an airplane propeller.

The torque converter in most American cars is a hydrodynamic transmission, placed ahead of the automatic transmission.

It was possible to drive the Dynaflow transmission without shifting the mechanical gears.

Hydrodynamic transmissions tend to be inefficient due to energy losses in the fluid.

Electric

Electric transmissions convert the mechanical power of the engine(s) to electricity with electric generators and convert it back to mechanical power with electric motors. Electrical or electronic adjustable-speed drive control systems are used to control the speed and torque of the motors. If the generators are driven by turbines, such arrangements are called turbo-electric. Likewise installations powered by diesel-engines are called diesel-electric. Diesel-electric arrangements are used on many railway locomotives.

Virtual transmission

Virtual Transmission allows for the same traction motor to be both a low-speed high torque and high-speed electric motor, using the winding/software that runs on the new electric motors, . This virtual transmission will require less complex engineering, and less weight [6][7] [8]. The alternator and starter for the Volt can be a single motor instead of two separate motors, that is smaller and lighter than each of the two motors individually [9].