MULTIPLE CHOICE QUESTIONS OF ENGINEERING DRAWING !

1-The following is not included in title block of drawing sheet.

1. Sheet No
2. Scale
3. Method of Projection
4. Size of sheet

(Ans: d)

2-Which of the following represent reducing scale?

1. 1:1
2. 1:2
3. 2:1
4. 10:1

(Ans: b)

3-In first angle projection method, object is assumed to be placed in

1. First quadrant
2. Second quadrant
3. Third Quadrant
4. Fourth quadrant

(Ans: a)

4-The following line is used for visible outlines

1. Continuous thick
2. Continuous thin
3. Chain thin line
4. Short zigzag thin

(Ans: a)

5-The following line is used for dimension line

1. Continuous thick
2. Continuous thin
3. Chain thin line
4. Short zigzag thin

(Ans: b)

6-The dotted lines represents

1. Hidden edges
2. Projection line
3. Centre line
4. Hatching line

(Ans: a)

7-Hatching lines are drawn at ___ degree to reference line

1. 30
2. 45
3. 60
4. 90

(Ans: b)

8-In aligned system of dimensioning, the dimensions may be read from

1. Bottom or right hand edges
2. Bottom or left hand edges
3. Only from bottom
4. Only from left side

(Ans: a)

9-The Length:Width in case of an arrow head is

1. 1:1
2. 2:1
3. 3:1
4. 4:1

(Ans: c)

10-Metric thread of 10mm diameter is represented by

1. 10M
2. M10
3. M^10
4. None of the above

(Ans: b)

11-The internal angle of regular pentagon is ___ degree.

1. 72
2. 108
3. 120
4. 150

(Ans: a)

12-The internal angle of regular hexagon is ___ degree.

1. 72
2. 108
3. 120
4. 150

(Ans: c)

13-‘Representative fraction’ (RF) is defined as

1. Length of an object in the drawing / Actual length of the object
2. Length of an object in the drawing / Isometric length of the object
3. Actual length of the object / Length of an object in the drawing
4. Isometric length of the object / Length of an object in the drawing

(Ans: a)

14-A line of 1 meter is shown by 1cm on a scale. Its Representative fraction (RF) is

1. 1
2. 100
3. 1/100
4. 1/50

(Ans: c)

15-A point ‘P’ is above Horizontal Plane (HP) and in front of Vertical Plane (VP). The point is in

1. First quadrant
2. Second quadrant
3. Third quadrant
4. Fourth quadrant

(Ans: a) 

CHAIN DRIVE,SHAFT DRIVE AND BELT DRIVE !! WHICH ONE IS GOOD ? WHY ?

The final drive on a motorcycle is the connection between the output shaft of the gearbox and the rear wheel. In scooters the engine is located at the rear, so that a simple gear train is used to put the power onto the rear wheels. In case of motorcycles, the distance between the output shaft and rear wheel is considerably higher. So it becomes necessary to use an appropriate drive which can transmit power and torque without much loss. 

Three most commonly used mechanism for transmitting torque and torque to rear wheels are :

1.)Chain Drive
2.)Belt Drive
3.)Shaft Drive

Chain Drive :

1. A chain drive system is used in almost all the bikes that we see on a daily basis, because it’s reliable and cheap to maintain.
2. It needs maintenance regularly. A chain drive system needs to be cleaned and lubricated after a gap of every 500 to 800 kilometres to protect the chain from getting dirty, rusted and dysfunctional. 
3. It works at almost 99% efficiency, where the remaining 1% is lost due to friction.
4. a chain drive system is capable enough to deal with high level torque produced in these machines, and almost all the dirt bikes and drag-focussed motorcycles feature a chain dive mechanism.

Cost of Maintenance – Medium

Cost of Replacement - Low

Maintenance Efforts – Very High

Power Loss :Very Low (Negligible) 

Belt Drive :

1. This mechanism is basically used in the cruisers, because the power delivery to the rear wheel using a belt drive system is more liner and smooth as compared to that with a chain drive system.
2. The belt does not require lubrication which is one major advantage over chain drive.
3. The life of these belts are comparatively lower, and requires frequent replacement due to wear and tear.
4. Out of the total power generated, only 91% is delivered to the rear wheel and the rest is lost during the transmission.

Cost of Maintenance – Low

Cost of Replacement – High

Maintenance Efforts – Nil

Power Loss :Low  

Shaft Drive:

1. This technology is the same as seen on cars. 
2. Shaft Drive provides the smoothest driving experience. Moreover, it has a longer life span then that of chain and belt drives.
3. The power loss in shaft drive is really high, about 25% due to extra gears and shaft.
4. It is more expensive and heavier because of the gears and technology.
5.  There is no maintenance required in a shaft drive.
6.  This system can be seen on bikes like Honda VFR 1200 and BMW K 1300S.

Cost of Maintenance – Very Low

Cost of Replacement – Very High

Maintenance Efforts - Nil

Power Loss :High

Finally,it depends on the application of the vehicle but when it comes to efficiency chain drive is most suitable mechanism for power transmission especially in Automobiles.

DIFFERENCE BETWEEN GAUGE PRESSURE AND ABSOLUTE PRESSURE EXPLAINED !!!

Introduction:

Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Mathematically, it is symbolized with a ‘P’. To put it briefly, it is the amount of force acting on a unit area. The simple formula for pressure is:

P = F / A; where P = pressure

F = force
A = area

The SI unit for pressure is in Pascals (Pa). Other non-SI units are PSI and bar.

There are two kinds of references to measure pressure ‘“ the gauge pressure and the absolute pressure. 

Absolute Pressure:

The actual pressure at a given position is called the absolute pressure and it is measured relative to absolute vacuum. One concept should be taken into consideration is that to measure any quantity we require a base line with respect we are going to measure it.

To learn this concept let us take an example, suppose we need to measure distance of Chennai.Distance can be measured in meter. Can we measure distance of Chennai by this input? Obviously your answer is no because we need a reference from which we want to measure distance. Now suppose we need to measure distance of Chennai from Delhi. Now we are able to measure this distance in some meters or kilometers.

Similarly pressure cannot be measured without a reference. When we take vacuum or no pressure condition as reference, the measured pressure is called absolute pressure.

Gauge Pressure:

When we take atmospheric pressure as reference to measure pressure of any system, the measured pressure is known as gauge pressure. Most of pressure devices work in atmospheric condition always measure gauge pressure. We can convert this gauge pressure in absolute pressure by adding atmospheric pressure in gauge pressure. 

It should be noted that atmospheric pressure may vary, depending on many factors, such as locality. Altitude and temperature are essential factors. The standard atmospheric pressure (1 ATM) is about 14.7 PSI.

P (absolute) =  P (Gauge) +  P (Atmospheric)

Most of gauge read zero in atmosphere but there is some atmospheric pressure. They read atmospheric pressure as absolute zero pressure. Pressure below atmospheric pressure is called vacuum pressure and is measured by vacuum gauges that indicate the difference between the atmospheric pressure and absolute pressure.

P (vacuum) = P (Atmospheric) – P (Absolute)

Machines like air compressors, well pumps, and tire gauges will all use gauge pressure. 

Summary:

1. Absolute pressure is measured in relation to the vacuum, while gauge pressure is the difference between the absolute pressure and the atmospheric pressure.

2. Absolute pressure uses absolute zero as it’s zero point, while gauge pressure uses atmospheric pressure as it’s zero point.

3. Gauge pressure is commonly used, while absolute pressure is used for scientific experimentations and calculations.

4. To indicate gauge pressure, a ‘g’ is placed after the unit. Absolute pressure, on the other hand, uses the term ‘abs’.

5. Due to varying atmospheric pressure, gauge pressure measurement is not precise, while absolute pressure is always definite.

6. Absolute pressure is sometimes referred to as ‘total systems pressure’, while gauge pressure is sometimes called ‘overpressure’.

KNOW THE HIDDEN SECRET BEHIND THE FOUR DOTS THAT YOU SEE IN NEWSPAPER !!

When printing an image that has more than one color, it is necessary to print each color separately and ensure each color overlaps the others precisely. If this is not done, the finished image will look fuzzy, blurred or "out of register" (see image to bottom). To help line the colors up correctly, a system of registration is necessary.

The four dots blue (cyan), pink (magenta), yellow and black are registration marks used during printing to help ensure the print is aligned properly. In offset printing technology, which newspapers use, the inked image is transferred from a plate to a rubber blanket, then to the printing surface. These primary colours go into printing a multi-coloured image and have separate plates. Each plate has its individual mark, like the colour dot.

WORKING OF GEAR PUMP EXPLAINED !!

External gear pumps are a popular pumping principle and are often used as lubrication pumps in machine tools, in fluid power transfer units, and as oil pumps in engines.Gear pumps are also widely used in chemical installations to pump high viscosity fluids.

Working of gear pump :-

External gear pumps are similar in pumping action to internal gear pumps in that two gears come into and out of mesh to produce flow.  However, the external gear pump uses two identical gears rotating against each other -- one gear is driven by a motor and it in turn drives the other gear.  Each gear is supported by a shaft with bearings on both sides of the gear.

1.  As the gears come out of mesh, they create expanding volume on the inlet side of the pump. Liquid flows into the cavity and is trapped by the gear teeth as they rotate.

2.  Liquid travels around the interior of the casing in the pockets between the teeth and the casing -- it does not pass between the gears. 

3.  Finally, the meshing of the gears forces liquid through the outlet port under pressure.
Because the gears are supported on both sides, external gear pumps are quiet-running and are routinely used for high-pressure applications such as hydraulic applications. With no overhung bearing loads, the rotor shaft can't deflect and cause premature wear.

Advantages :-

• High speed
• High pressure
• No overhung bearing loads
• Relatively quiet operation
• Design accommodates wide variety of materials

Disadvantages :-

• Four bushings in liquid area
• No solids allowed
• Fixed End Clearances

Applications :-

Common external gear pump applications include, but are not limited to:

• Various fuel oils and lube oils
• Chemical additive and polymer metering
• Chemical mixing and blending (double pump)
• Industrial and mobile hydraulic applications (log splitters, lifts, etc.)
• Acids and caustic (stainless steel or composite construction)
• Low volume transfer or application

FUNCTION OF SPOILER IN CARS EXPLAINED !!

The device we see at the rear of a car is known as spoiler.It is an automotive aerodynamic device whose intended design function is to 'spoil' unfavorable air movement across a body of a vehicle in motion, usually described as turbulence or drag. 

When car is running at high speed, two basic aerodynamic forces act on the car,first one is lift and second one is drag.The lift force tends to lift the car from the ground as a result the grip is reduced and vehicle becomes unstable.

A spoiler is fundamentally an inverted aircraft wing. The wings of a aircraft generates lift which helps the aircraft take off. While the spoilers also generate lift, because they are inverted, they push the car down on the ground.Thus,it increases the car’s grip on the road.

Without spoilers, the only way to increase the grip would be to increase the weight, or to change the compound the tire was made out of. The only problem with increasing the weight is that it doesn't help in turns, where you really want to grip. All that extra weight has inertia, which you have to overcome to turn, so increasing the weight doesn't help at all.Also,increased weight will result in increased fuel consumption.

Spoilers  on commercial vehicles are generally added for styling purposes and have either little or no aerodynamic benefit.