CHECK OUT THE MEANING OF "TDI" WRITTEN ON BACK OF VOLKSWAGEN CARS

CHECK OUT THE MEANING OF "TDI" WRITTEN ON BACK OF VOLKSWAGEN CARS :-

Turbocharged direct injection engine is invented by Volkswagen group. TDI identifies all advanced diesel engines using direct fuel injection and a turbocharger. TDI engines are economical and smooth with high levels of torque and good energy efficiency.

Working of TDI

Fuel needs oxygen to burn and the engine has to be supplied with huge quantities of air to get enough. You can solve this problem with a bigger engine - or you can solve it with a turbocharger - as in the TDI. Driven by the exhaust gases, it squeezes air more tightly into the cylinders.

After being drawn through the turbocharger the air is then cooled by passing it through an intercooler, before entering the combustion chamber where diesel is injected directly into the cylinders at very high pressure through a nozzle. It's this intensive mixing of highly atomized fuel with the cooled compressed air that leads to better, more efficient combustion.

Your driving experience is quiet and refined because effective sound keeps noise to a minimum, while hydraulic engine ensure smooth, low-vibration running.

MULTIPLE CHOICE QUESTIONS ON TRIBOLOGY

MULTIPLE CHOICE QUESTIONS ON TRIBOLOGY:-

1-The following is (are) the example(s) of static friction

1. Shoe brake applied to a vehicle
2. Shoe brake applied to a train
3. Dry grinding stone abrades the surface of metal
4. All of the above

(Ans: d)

2-As per laws of dry friction, the frictional force

1. depends upon the nature of sliding surface
2. is independent of the sliding velocity
3. is directly proportional to the load
4. All of the above

(Ans: d)

3-Lubricant converts

1. Solid friction into liquid friction
2. Liquid friction into solid friction
3. both ‘a’ and ‘b’
4. None of the above

(Ans: a)

4-The following is not a type of sliding contact bearing

1. Ball bearing
2. Journal bearing
3. Bush bearing
4. Thrust bearing

(Ans: a)

5- The following is not a type of roller contact bearing

1. Ball bearing
2. Journal bearing
3. Roller bearing
4. All of the above

(Ans: b)

6-In thrust bearings, the load acts

1. perpendicular to the axis of shaft
2. in axial direction
3. both ‘a’ and ‘b’
4. None of the above

(Ans: b)

7-Boundary friction conditions may develop in journal bearings, when shaft passes through zero speed during

1. starting
2. stopping
3. reversing
4. All of the above

(Ans: d)

8-The following lubricants are obtained by fractional distillation of petroleum

1. Mineral oils
2. Fatty oils
3. Solid lubricants
4. All of the above

(Ans: a)

9-For low pressure and low speeds, we use

1. Mineral oils
2. Semi-solid lubricants
3. Solid lubricants
4. All of the above

(Ans: c)

10-The pour point test is employed to indicate the suitability of oil for ____ temperature operations.

1. low
2. high
3. both ‘a’ and ‘b’
4. None of the above

(Ans: a)

11-The flash point of lubricant must be _______ the working temperature.

1. well below
2. well above
3. equal to
4. None of the above

(Ans: b)

12-Specific gravity of lubricant can be measured by using

1. Hydrometer
2. Viscometer
3. Anemometer
4. Pyranometer

(Ans: a)

13-API number of water is

1. 1
2. 5
3. 10
4. 20

(Ans: c)

14-The colour code for various grades of lubricants is as follows

Grade of lubricant	Colour code
A. Spindle oil	1. Red
B. Heavy-medium	2. Orange
C. Heavy/Extra heavy	3. Brown
D. Grease	4. Yellow

The correct order is

1. A-3, B-1, C-2, D-4
2. A-4, B-3, C-1, D-2
3. A-1, B-2, C-3, D-4
4. A-4, B-3, C-2, D-1

(Ans: b)

15-The bi-weekly lubrication is indicated by

1. rectangle
2. triangle
3. circle
4. hexagon

(Ans: c)

16-The monthly lubrication is indicated by

1. rectangle
2. triangle
3. circle
4. hexagon

(Ans: a)

17-Lubrication Oil from automobile machines come under ____ oil.

1. Clean oil
2. Less dirty
3. More dirty
4. Highly dirty

(Ans: d)

18-The six monthly lubrication is indicated by

1. rectangle
2. triangle
3. circle
4. hexagon

(Ans: d)

DIFFERENCE BETWEEN NC AND CNC MACHINE

In today’s world every manufacturing industries wants high accuracy products in less time. And this complexity of high accuracy in minimum time can be achieved by use of NC and CNC machine. Here we will discuss about the basic differences between them.

Difference Between NC and CNC machine

The various difference between NC and CNC machine  in tabular form are as follows:

S.no	NC Machine	CNC Machine
1.	Here NC stands for Numerical Control	CNC stands for Computer Numerical Control.
2.	It is defined as the machine which is controlled by the set of instructions in the form of numbers, letters and symbols. The set of instructions is called as program.	It is defined as the machine which is used to control the motions of the workpiece and tool with the help of prepared program in computer. The program is written in alphanumeric data.
3.	In NC machine the programs are fed into the punch cards.	In CNC machine the programs are fed directly into the computer by a small key board similar to our traditional keyboard.
4.	Modification in the program is difficult.	Modification in the program is very easy.
5.	High skilled operator is required.	Less skilled operator is required.
6.	Cost of the machine is less.	Cost of the CNC machine is high.
7.	Maintenance cost is less	Maintenance cost is high.
8.	The programs in the NC machine cannot be stored.	In CNC machines, the programs can be stored in the computer and can be used again and again.
9.	It offers less flexibility and computational capability.	It offers additional flexibility and computational capability.
10.	The accuracy is less as compared with the CNC.	It has high accuracy.
11.	It requires more time for the execution of the job.	It takes very less time in the execution of the job.
12.	It is not possible to run it continuously.	It can be run continuously for 24 hours of a day.

Comparison Between NC and CNC Machine

The comparison of NC and CNC machine are:

• NC stands for Numerical Control whereas CNC stands for Computer Numerical Control.
• In NC Machine the programs are fed into the punch cards. But in CNC machine the programs are fed directly into the computer with the help of a small keyboard similar to our traditional keyboard.
• In NC machine if and error occurs in the program than its debugging and modification is not easy. In CNC machine the debugging and modification is very easy.
• High skilled operator is required to operate the NC machine whereas to operate a CNC machine, a semiskilled operator may work.
• The cost of the NC machine is less as compared with the computer control machines.
• The maintenance cost of NC is less whereas it is costly in the case of CNC machine.
• No programs can be stored in the NC machine. In CNC machine, numbers of programs can be stored and can be used again and again for the production.
• The accuracy of the NC is less as compared with the CNC.
• In NC machine the execution of the job takes more time but the CNC machine executes the job without taking much time.
• NC cannot be run continuously for 24 hours but CNC machine can be run for 24 hours continuously.