TORQUE CONVERTER

Torque converter is a type of fluid coupling that uses a fluid to transmit turning effort from the one shaft to another. It is a device which performs a function similar to that of a gear box, namely, to increase the torque while
reducing the speed. A gear box provides only a small number of fixed ratios, but the torque converter provides a continuous variation of ratio from the lowest to the highest.The torque convertor is somewhat similar to a fluid fly wheel, but differs from it in one aspect, namely it has three principal components instead of only two.

Torque converter consists of

(i) The driving element or impeller or pump which is connected to the engine.

(ii) The driven element or rotor or turbine which is connected to the propeller shaft and

(iii) The fixed element or reaction member or stator which is fixed to the frame. The fixed element is responsible to cause a change of torque between input and output shafts. The fluid flywheel does not have any fixed member, as such cannot produce any change of torque.

Working of a torque converter

The three element torque converter can be seen in the picture. In the torque converter, torque multiplication take place in the following way. The oil leaving vanes hits the stator vanes. This oil is redirected into the pump vanes in a direction which helps the pump operation. This oil is again thrown into the turbine by the pump. In fact, this is a continuous process. The fluid pushing repeatedly on the turbine vanes increases the torque on the turbine. In many designs of torque converters, the torque is almost doubled. However, as the speed of the turbine approaches the speed of the pump, the increase in torque falls of gradually till it becomes 1:1. At this stage, the oil starts striking the rear faces of the vanes in the stator, thus making the stator to turn. Now the stator does not take part in torque converter action. Under these conditions, the torque converter simply acts as a fluid fly-wheel.

The over running clutch or freewheeling device is used for mounting the stator. The spring loaded rollers in the freewheel allow the stator to freewheel when the oil starts striking the rear of the stator vanes. On the other hand, when the oil strikes the front of the stator vanes, it attempts to rotate the stator in the opposite direction. But this action locks up the freewheeling device and thus holds the stator stationary. Under such condition, the stator acts as a reaction member, and directs the oil leaving the turbine trailing edges in the proper direction before it enters the pump vanes.

LATHE MACHINE

Lathe machine is a basic machine which is used in every metal forming industries. It is combination of many parts which works together to perform a desire function. A lathe machine is used to machine cylindrical work piece which is 360 degree symmetrical form the axis of rotation. It used to perform turning, chamfering, boring, facing, internal threading, shaping, slot cutting etc. on cylindrical work piece.

There are many types of lathe machine but each machine consist some basic part which are essential for its proper working. These parts are bed, tool post, Chuck, head stock, tell stock, legs, Gear chain, lead screw, carriage, cross slide, split nut, apron, chip pan, guide ways etc. These parts work together to obtain desire motion of tool and work piece so it can be machined. 

The lathe machine works on basic principle that when the work piece rotate at a constant speed and a tool is introduce between its rotation, it cut the metal. This is basic fundamental of it. The working of lathe machine is explained in later section of this article.

Lathe machine: Main Parts, Operation and Working

We have briefly discussed about parts and working of lathe machine in upper section of this article. Now we will describe it.

Parts of Lathe Machine:

The lathe consist following parts.

1. Bed

It is the main body of the machine. All main components are bolted on it. It is usually made by cast iron due to its high compressive strength and high lubrication quality. It is made by casting process and bolted on floor space.  

2. Tool post

It is bolted on the carriage. It is used to hold the tool at correct position. Tool holder mounted on it.

3. Chuck

Chuck is used to hold the workspace. It is bolted on the spindle which rotates the chuck and work piece. It is four jaw and three jaw according to the requirement of machine.

4. Head stock

Head stock is the main body parts which are placed at left side of bed. It is serve as holding device for the gear chain, spindle, driving pulley etc. It is also made by cast iron.

5. Tell stock

Tell stock situated on bed. It is placed at right hand side of the bed. The main function of tell stock to support the job when required. It is also used to perform drilling operation.

6. Lead screw

Lead screw is situated at the bottom side of bed which is used to move the carriage automatically during thread cutting.

7. Legs

Legs are used to carry all the loads of the machine. They are bolted on the floor which prevents vibration.

8. Carriage

It is situated between the head stock and tell stock. It is used to hold and move the tool post on the bed vertically and horizontally. It slides on the guide ways. Carriage is made by cast iron.

9. Apron

It is situated on the carriage. It consist all controlling and moving mechanism of carriage.

10. Chips pan

Chips pan is placed lower side of bed. The main function of it to carries all chips removed by the work piece.

11. Guide ways

Guide ways take care of movement of tell stock and carriage on bed.

12. Speed controller

Speed controller switch is situated on head stock which controls the speed of spindle.

13. Spindle

It is the main part of lathe which holds and rotates the chuck.

Lathe Machine Operation & Working:

Lathe machine is used to cut the metal from cylindrical work piece, and convert it into desire shape. It turns the cylindrical work piece, and during turning a sharp edge cutting tool introduce, which cuts the metal. Its working can be described as follow. 

1. A cylindrical work piece fixed to the chuck. A chuck may have three jaw or for jaw according to the requirement. The work piece is at the center or some eccentric according to the process perform.

2. The spindle starts to rotate and set it at desire speed. The spindle speed plays a huge role during cutting. The spindle rotates the chuck and work piece.

3. Now check the work piece is turning properly. If it not set the work piece using dial gauge.

4. Now set the tool at desire feed by moving the tool post and carriage. The feed also play main role during cutting. Large feed may cause unwanted temperature increase.

5. After it tool is introduce between moving work piece at desire feed rate. It cut the metal from work piece. The feed rate is set at the cutting condition.

6. Now all unwanted metal is removed by moving the carriage form horizontally and vertically as desire according to the job requirement. After complete all process we got a well finished job.

7. Lathe can perform turning, boring, chamfering, shaping, facing, drilling knurling, grooving as shown in figure.

CARNOT CYCLE

Carnot cycle is one of the air standard cycle. It is given by a French engineer, Sadi Carnot so named as Carnot cycle. This is an ideal cycle of all thermodynamic cycle because it gives maximum efficiency between two temperature difference.
When we study about any other cycle, we compare it to the Carnot cycle, which will give the maximum work output between these temperature range.

In air standard cycle we assume air as the working fuel but actually air with fuel use as working fluid. In Carnot cycle analysis we assume that air is used as the working fluid and it complete a cyclic process. So in Carnot cycle air standard analysis we assume a reciprocating engine in which air is filled which act as the working fluid. A heat reservoir is used at head for Heat addition and heat rejection. 

Carnot cycle is combination of four thermodynamic process, in which two are isothermal processes and the remaining one are isentropic processes. 

Isothermal process is also known as constant temperature process in which temperature of working fluid remain constant until process done. In isentropic process the entropy of system remain constant which mean the system would not emit or absorb heat until whole process. The combination of this process makes the Carnot cycle.

Working of Carnot Cycle:

As we have discussed Carnot cycle is the combination of two isothermal processes and two isentropic processes. In Carnot cycle heat is add or removed at constant temperature and expansion and compression done isentropically.

In Carnot cycle we assume a piston cylinder device which is insulated from surrounding. No heat can add or removed from the system. The head of the system can be replaceable during process by the heat reservoir. At the starting the piston is at the top or at top dead center of cyclinder. At this position the insulated head replaced by the higher temperature heat reservoir which add the heat energy into the system by Zeroth law. This heat energy move or expand the piston downward. One thing note that the heat energy added by reservoir does not rise the temperature of the system. It only done work by expanding piston So this process is done isothermically. 

When the piston reaches mid of the cylinder, the head is replaced by the insulated head so no heat can add into the system but due to inertia of the piston, it expand continuously by using the heat of the working fluid (Air) which down the temperature of the system. Because no extra heat is added into the system, this process done issentropically. At this point piston reaches its maximum downward limits or at bottom dead center. 

Now the cylinder head replaced by the lower temperature heat reservoir which absorb the heat from the system. Due to this the air contracts to maintain its temperature constant. The piston moves upward or compresses the air. In this process the heat removed by the system used to compress the system and the temperature of system remains constant. So the compression done isothermically. 

When the piston is at mid of the cylinder the heat reservoir at head replaced by the insulated head. So no head is removed from system at this end. Due to inertia of piston it moves continuously upward which compressed the air and increase its temperature. No heat is added or removed until this compression so this process done issentropically. At this point the piston reaches its initial condition (Top dead center), so complete a cyclic process. The working fluid (Air) also reached its initial condition so it completes a thermodynamic cycle.

Air Standard Analysis of Carnot Cycle:

As we discuss in upward paragraph that a Carnot cycle consist four processes. These are:-

1. Isothermal Expansion:

In this process the heat is added into the system and the piston expand isothermally. In this process the temperature of the air remains constant.

The amount of heat added to the system is given by the isothermal process is :

Q_{heat addition} = mRT₁log(V2/V1) 

           = mRT₁log(r) 

Where is r is compression ratio.

2. Isentropically Expansion:

In this process the no heat is added into the system and the piston expand isentropically. In this process the temperature of air decreases from the initial temperature. In this process work done by the system.

The work done during this isentropic process is given by 

Work done =  (P2V2 - P3V3) / ( γ - 1 )

Where γ is specific heat ratio of air. 

3. Isothermically Compression:

In this process the air is compressed and heat is removed from the system. In this process the temperature of the air remains constant.

The heat removed by the system is given by the isothermal process is :

Q _{heat removed} = mRT₃log(V4/V3)

              = mRT₁log(r) 

Because V4/V3 = V2/V1 = r

4. Isentropically Compression:

In this process the no heat is added into the system and the piston compress the air isentropically. In this process the temperature of air increases from the initial temperature. In this process the work done on the system.

The work done during this process given by isentropic process is :

Work done =  (P1V1 - P4V4) / ( γ - 1 )

Where γ is specific heat ratio of air. 

Carnot Cycle Efficiency:

Efficiency of carnot cycle is analyzed thermodynamically. The efficiency of any engine given by

η = Work done / Heat supplied

Work done = Heat supplied - Heat rejected

Work done =  mRT₁log(r)  -  mRT3log(r) 

                =   mRlog(r) [T₁ - T3] 

Because heat supplied and heat rejected isothermically which is given by

η = Work done  / Heat supplied

   =  mRlog(r) [T₁ - T3]  /  mRlog(r)T₁

   =   [T₁ - T3] / T₁

    =  1 - T3/T1

           

From the above equation , we see that the efficiency of Carnot cycle increases by increasing higher temperature of cycle (T₁) or by decreasing the lower temperature of cycle (T3).

It is impossible to make a engine work on Carnot cycle because to achieve isothermal expansion and compression the piston should run extremely slow to ensure that the air is always at same temperature and isentropic expansion and compression should carried out as fast as possible to no exchange of heat.

Between two fixed temperatures Carnot cycle has the maximum possible efficiency compared to other slandered cycles. The Carnot cycle does not have any real life example so it is ideal cycle not a practical cycle. 

5 AMAZING FACTS ABOUT AUDI

5. THE NAME AUDI IS THE LATIN FOR “HEAR”

August Horch founded his first car company, A. Horch & Cie. in 1899. But just 10 years later, Horch wasn’t seeing eye-to-eye with his Chief Financial officer and left his own company to start August Horch Automobilwerke GmbH. Unfortunately, Horch soon learned the Horch name belonged to his former company when he was notified of a copyright infringement.
In response, Horch changed the new company’s name to the latin translation of his last name. In German “horch” means “hear,” which in Latin is “audi”.

4. THE FOUR RINGS IN THE LOGO REPRESENT THE FOUR COMPANIES OF AUTO UNION

Four car companies make up the Audi Company and the four-ring logo represents each one of the companies. DKW, Horsch and Wanderer are the three other companies of the “quattro”. This was also known as the Auto Union.

3. AUDI HAS BEEN CONDUCTING CRASH TESTS FOR OVER 75 YEARS

In 1938, crash tests were first carried out by Audi. These tests gave the company an idea about how the car would behave in case an accident occurred. Without realizing it, the company had set a precedent for all other car manufacturers.

2.THERE ARE 36520 STITCHES ON THE LEATHER INTERIORS OF AN AUDI A8.

1. THE FIRST AUDI RS MODEL WAS CO-DEVELOPED WITH PORSCHE

The RS 2 was the first of Audi’s high-end performance cars and the first of a long line of fast Audi wagons. It would have never happened without the performance expertise of Porsche.

Bodyshells from the Audi 80 estate, on which the RS 2 was based, were shipped to Porsche in Stuttgart, where they underwent a thorough transformation. The turbocharged 2.2 liter 5-cylinder was tuned by Porsche to produce 311 horsepower. Porsche also supplied the braking and suspension systems.

Thanks to its quattro all-wheel-drive, and the Porsche tuned engine, the RS2 was able to out sprint the venerable McLaren F1 to 30 mph.

10 UNBELIEVABLE FACTS ABOUT MARUTI 800

The Maruti 800 has changed the way India looks at cars. The historic year of 1983 saw the launch of the first modern four-door hatchback in India.
 The car lived as an undisputed market leader throughout its life but was then forced out of the market by Maruti itself. Yes, it’s crazy but true. Here are some more such few crazy facts that we bet you did not know about the India’s favourite hatchback.

1.Retailed for under Rs. 50,000

When launched in 1983, the car retailed at Rs. 48,000 only. The demand was so much that customers were willing to shell out more than Rs. 1 lakh for the car. Maruti 800 became a hot-seller at that time, the alternatives were far more expensive and lacked the convenience of a small car.

2.The only car whose top speed exceeded the speedo marking

Often we try to touch the top speed mentioned in the speedometer console of our cars and fail to do that. The Maruti 800 could go past the mentioned top speed of 140 km/h on the console. This insane feat was achieved only by the limited edition – Maruti 800 5-speed. This edition of Maruti 800 could do a top speed of 144 km/h.

3.The first buyer of Maruti 800 never upgraded

The first owner of Maruti 800 in India – Mr Harpal Singh received the keys of the car from then prime minister of India – Indira Gandhi on December 14, 1983. Mr Harpal owned the car for nearly 27 years. He did not sell the Maruti 800 either did he upgrade to a new car. He passed away in 2010 and the car still belongs to the family.

4. 3 lakh people have died in Maruti 800s

Recent data released by Dr Kamal Soi, a member of National Road Safety Council of Ministry of Road Transport and Highways based on FIRs, paints a chilling picture of the car. The FIRs in National Crime Records Bureau have revealed that over 3 lakh people lost their lives in the accidents involving Maruti 800.

5.Most stolen car in Pakistan

The Maruti 800 is the most stolen car in Pakistan according to a statement released by Karachi’s Anti-car lifting cell unit. The 800 is known as Suzuki Mehran in Pakistan and is loved by thieves. White coloured cars are the worst affected, said the unit.

6.Was first mooted in the 1950s, but took 3 decades to be productionized

It was late 1959 when the idea of cheap small cars was floated by Manubhai Shah, a Union minister in Nehru’s cabinet. The concept was then overtaken by a committee headed by L.K. Jha but it did not materialise till the 1980s. That is a long time for bringing the small car into the Indian market.

7.First-ever front wheel drive car in India

The car was launched during the reign of Hindustan Contessa, Ambassador and Premier Padmini. All the cars were bulky with rear wheel drive set-up. The Maruti 800 became the first car in India to be offered with a front-wheel-drive configuration that reduced the weight and the cost of the car considerably.

8.Maruti 800 was forced out of the market

In the year 2000, Maruti launched the Alto that eventually replaced the 800 in India. The Alto was launched as a bigger and stylish alternative to the 800. Even the launch of Alto could not dislodge the 800 from the top spot of sales.

Maruti plonked the 796cc, 12-valve engine of the Alto in the Maruti 800 that was mated to 5-speed gearbox and produced a maximum of 45 Bhp. The lightweight car with the new engine could go past 140 km/h and became a super hit in the market.

Seeing the popularity, Maruti was forced to put the old 2 valves per cylinder engine and the 4-speed gearbox back in the 800.

The stricter BS-IV norms were introduced in the top cities and metros of India stopping the sale of the 800 in these cities. Eventually, the production of 800 was stopped in February 2014.

9.Well maintained examples sell for BIG money

The Maruti 800 holds a lot of heritage and history. If the car is maintained in running conditions, it could fetch close to Rs. 2 lakh in the current market. Even the first generation models that had a sticker price of below Rs. 50,000 can fetch such value in the market. This car does not know what depreciation is.

10.Was the first car of many celebrities

Many celebrities chose the icon before it became an icon. The Maruti 800 became the first car of Master Blaster – Sachin Tendulkar, who wanted to buy the car in 1983 itself but could not do that because of funds. Sachin saved money for few years and gathered enough to buy the car. The blue Maruti 800 is still parked in Sachin’s garage.

Another notable celebrity to buy the Maruti 800 is Shah Rukh Khan. He bought the car in Delhi and drove it down to Mumbai.