Posted tagged ‘diesel engine’

Frequently Asked Interview Questions for Mechanical Engineers!!

September 18, 2011

1.         What is friction?

2.         What is gear ratio? How it can calculate

3.         What is gyroscopic and gyroscopic effect?

4.         What is mean by Resistance welding
5.         What Is Mean By Ss-314(Stainless Steel Pipe Grade)?
6.         What is pulverization?
7.          What is requirement of bottle filling machine
8.          What is Solution Annealing? kindly explain its process in brief.
9.          What is the basic need for designing the bottle filling machines
10.        What is the critical speed. Compare the critical speed of hollow shaft and solid shaft.
11.        What is the definition of mechanical
12.        What Is The Difference Between Rated Speed And Economic Speed?
13.        What Is The Difference In Is2062 And Is1239
14.        What is the difference between construction of reaction turbine and impulse turbine
15.        What is the difference  between Torque and Power ( layman Idea)?
16.        What is the manufacturing process for impellers of closed, semi open and open type?
17.        What is the principle of operation of simple jet propulsion system?
18.        What is the relationship between cop and hp(horse power) of compressor?
19.        What is the thermodynamics?
20.        What is the use of vanadium (non metal) ?
21.        What is thermodynamics?
22.        What is unit Ps ?
23.        What’s the difference between front and rear wheel drive? on what basis we choose the type of drive?
24.        Whats the range of poissons ratio of a stable material??
25.        When a solid shaft is subjected to tension its linear dimension changes equally as its lateral dimension,then what will               be its poissons
26.        Whether ductile material can fail in brittle manner? WHEN?
27.        Which engine is more suitable over all. petrol engine, diesel engine . what are their differences
28.        Who are the leaders among expansion valve manufacturers? what are the recent developments in the expansion                     valve industry, used in refrigeration abd air-conditioning?
29.        Why Air Conditioner capacity measured in Ton. Like 1.5ton
30.        Why as atmospheric pressure increases,boiling point also increases?
31.        Why desuperheater tubes are bend in shape
32.        Why diesel engine does not have spark plug like petrol engine, how ever petrol is better fuel than diesel?
33.        Why does cycle rim don’t bend even in heavy loads?
34.        Why green curtons are used in hospital?
35.        Why petrol engine gives more power than diesel engine even though diesel engine has high compression ratio?
36.        Why petrol engines have more power than diesel engines of same capacity?
37.        Why the back wheel of tractor is bigger than front wheel?
38.        Why the path of a satellite is always elliptical with earth not at the center of the ellipse?
39.        Why tyres are manufactured in black colour?
40.        Why we cant measure absolute entropy directly,but the change we can?
41.        Why we express the unit of torque in Nm.even though it can be expressed as Joule ( J )?
42.        Why we have to know the specific frequency of any equipment? does anybody know about specific frequency ?
43.        Will you tell me about types and numbers of sensors in Toyota Corolla GLI, Honda Civic and Suzuki Cultus VXRI?
44.        Write down the expression for air standard efficiency of diesel cycle?
45.        You have to design a machine component. For what type of failure (ductile or brittle) you will design?
46.        Even though LPG is economical than petrol,why we are not promoting LPG usage?
47.        Explain bearing nomenclature with example.
48.        Explain Why Nozzles are made convergent and Divergent?
49.        Function of clutch?
50.        How a Diesel Engine Works in Generators?Explain with Labeled Diagram.
51.        How can u increase the efficiency of power plant without changing in effort?
52.        How gravity filling machine is designed
53.        How Hydraulic Power Steering & Clutch works please explain ?
54.        How much efficiency loss will took place in a steam turbine due to low vacuum
55.        how to calculate the speed of conveyor in meter per minute
56.        How to convert from HP to BHP or CC to BHP please explain?
57.        How to find rating of Chiller a.c. plant i.e. how to calculate the a.c. load of an area, needed by Chiller ?
58.        How to measure sound level of engine of tractor?
59.        How turbo charger works?
60.        If I want to set a power plant in desert of ‘Rajasthan’ and I have option of steam and gas power plant. Which plant I                 should set up?
61.        If the blade height is increased,then how it increases the specific speed of centrifugal pump?
62.        If u have to give support in 1 km long bridge,where u will give it & how many?
63.        In a Waste heat recovery boiler feed control valve is after the economizer where as in auxiliary boiler feed control                   valve is given before the economizer.why?
64.        In auto mobile industry for any type of vehicle how can we differentiate 2 stroke and 4 stroke engine….
65.        In hydraulic clutch mechanism can i adjust clutch play? if it is possible please explain ?
66.        increase in unit speed increases the discharge of impulse turbine how?
67.        Name fuels used in nuclear power plant?
68.        On what property u can distinguish material as brittle or ductile?
69.        On what thermodynamic cycle nuclear power plant works?
70.        Pipe. Whats The Concept Behind It?
71.        Purpose of centrifugal pump casing wear ring and impeller wear ring what is back plate in centrifugal pumps and its                 purpose?
72.        Suppose a steel bar of cross sectional area A is subjected to load P at one end and 2P at the other end ,what will be                  the induced
73.        What is vaily gap in welding?
74.        What are engines that use carburetor and that use inductor ? difference between them
75.        What are the conditions considered while evaluating MARGIN OF SAFETY for newly designed mechanical                                components….?
76.        What are the types of welding machine?
77.        What are your significant functional achievements in the present company? How did they contribute to the total                       process
78.        What do you mean gy “Clausius inequality”?
79.        What does a pump develops? Flow or Pressure. Give the Answer with Proper Logic.
80.        What for orifice using in liquid flow line
81.        What is bearing? how many types of bearing
82.        What is difference between sand blasting and grit blasting ? What is its purpose and how is it done ?
83.        What is drive speed & what is driven speed
84.        What is Dry Bulb Temperature and Wet Bulb temperature?
85.        what is electronically operated pneumatic valves? give one example
86.        What is FEED?
87.        A bearing is designated as 6205 , what is it’s bore diameter?
88.        Advantages and disadvantages of using LPG in car?
89.        All Rector or Exchanger have spherical/hemispherical end Why?
90.        Compare Bray-ton and Otto cycle.
91.        Current rating of a 3 phase DG set is 20 Amps, but what will be the per phase current for single phase supply.
92.        Define Overall Heat transfer coefficient.
93.        Does Is 2062 Specifies Only Seamless Pipes Or Erw Pipe Is Also Covered Under Is 2062

MECHANICAL GOVERNORS

September 13, 2011

 

Diesel Fuel Systems
Mechanical Governors
This Meeting Guide is the third in a series dealing with the basic
diesel engine fuel system and components. It is about the diesel
governor.
Fig. 01Each Caterpillar diesel engine is equipped with a governor. Why?
Diesel engines can accelerate-increase speed-at the rate of more
than 2000 revolutions per second. Yes, PER SECOND. Without a
governor a diesel engine can quickly destroy itself.
Fig. 02
GOVERNORSNever operate a diesel engine without a governor controlling it. If
you were to move the fuel rack of a diesel engine to the full “ON”
position without a load and with the governor not connected, the
engine speed might climb and exceed safe operating limits before
you could shut it down. One second…two seconds…before you
knew what was happening, the engine may have been seriously
damaged by overspeeding.
This warning – never operate a diesel engine without a governor
controlling it – is concerned with one of the purposes of governors:
to prevent engine overspeeding. Governors also keep the engine at
the desired speed and increase or decrease engine power output to
meet load changes. WARNING

Fig. 03This presentation introduces and explains the mechanical governor.
The mechanical governor is the simplest of the various types of
governors and is basic to their operation.
Besides the mechanical governor, Caterpillar engines use: servomechanical
governors, hydraulic governors and electronic
governors. These governors will be discussed in future
presentations.
MECHANICAL
Fig. 04This tractor is equipped with a mechanical governor. We can see the
governor control lever, the control linkage, the governor and the fuel
injection pump housing.

Fig. 05.
This is a closeup of the governor, mounted on the rear of the fuel
injection pump housing.
Let’s look at the construction and operation of the mechanical
governor using schematic illustrations.
Fig. 06Diesel engine mechanical governors consist of two basic
mechanisms: the speed measuring mechanism and the fuel changing
mechanism.
Fig. 07
The speed measuring mechanism senses engine speed changes, and
the . . . .
Fig. 08. . . fuel changing mechanism increases or decreases the amount of
fuel supplied the engine to correct these changes.
Let’s look at each basic mechanism separately and learn how it
operates.

Fig. 09
The speed measuring mechanism is simple, has few moving parts
and measures engine speed accurately. The main parts are:
1) gear drive from the engine,
2) flyweights, and
3) spring.
Fig. 10The flyweights and “L” shaped ballarms which pivot are mounted
on the governor drive.

Fig. 11
The flyweights are rotated by the engine.
Fig. 12As the flyweights rotate, they exert a centrifugal force outward. The
flyweights move outward pivoting the ballarms upward. The amount
of outward force depends on the speed of rotation.
Centrifugal force is the basic operating principle of the speed
measuring mechanism. Now, what is centrifugal force?

Fig. 13
If we tie a ball on a string . . . .
Fig. 14. . . . . and swing it around and around . . .

Fig. 15
faster and faster, an outward force-centrifugal force- is exerted on
the ball. This centrifugal force swings the ball outward and upward
until the ball is nearly straight out.
And, we can see that the faster we swing it, the greater the pull on
the string and the farther outward it swings.
Fig. 16This force – centrifugal force – is the basic principle used in the
speed measuring operation of the diesel engine governor. Keep
centrifugal force in mind as we discuss the other parts of the speed
measuring mechanism. Remember, the greater the engine speed, the
greater the centrifugal force and, therefore, the greater the
movement of the flyweights and ballarms.

Fig. 17
We need to control this centrifugal force, so we have the governor
spring. The spring acts against the force of the rotating flyweights
and tends to oppose them. The force exerted by the spring depends
on the governor control setting.
Fig. 18
A lever connected to the governor control pushes on or compresses
the spring. The spring force opposes the flyweights to regulate the
desired engine speed setting.
The governor control, shown here as a simple push-pull knob, may
be a hand operated control lever or a foot operated accelerator
pedal.
Fig. 19
As long as the spring force equals the flyweight centrifugal force,
engine speed remains constant.
Fig. 20
The speed measuring mechanism, then, senses and measures engine
speed changes. The fuel changing mechanism links the speed
measuring mechanism with the fuel injection pumps to control
engine.
Fig. 21The fuel changing mechanism consists of the:
1) connecting linkage,
2) rack and
3) the fuel injection pump.
Fig. 22
Flyweight movement – outward in this example – due to engine
speed changes, are transferred through the simple linkage to the
rack and, therefore, to the fuel injection pump plunger.
Fig. 23When the engine load increases – as when a dozer digs in – the
speed decreases. The flyweight force decreases, and the spring
moves the linkage and rack to increase the fuel to the engine. The
increase fuel position is held until the engine speed returns to the
desired setting, and the flyweight force again balances the spring
force.

Fig. 24
When the engine load decreases, the speed increases. The flyweight
force increases, overcoming the spring force, moving the rack to
decrease fuel to the engine. The decrease fuel position is held until
engine speed returns to the governor control setting, and the spring
force again balances the flyweight force.
Fig. 25
In summary, the basic governor consists of the:
drive gears, flyweights, spring, and control lever of the speed
measuring mechanism, and the connecting linkage, rack and fuel
injection pump of the fuel changing mechanism.
Fig. 26
The rack which meshes with the injection pump plunger gear
segments extends from the injection pump housing into the
governor. The rack and fuel injection pumps are parts of the fuel
injection pump housing assembly.
Fig. 27As you recall, Meeting Guide 43, Fuel Systems: Part 2, explained
fuel injection pump operation and how the fuel injected into each
cylinder is increased or decreased.

Fig. 28
In this cutaway governor and fuel injection pump housing, we see
that the rack extends into the governor. Rack movement controls the
amount of fuel injected in each cylinder.
Let’s look at a closer view of our cutaway governor.
Fig. 29In this cutaway section of our housing, see the flyweights, spring,
spring seat and thrust bearing. The thrust bearing (not previously
mentioned) is an anti-friction bearing between the flyweight
ballarms which rotate and the spring seat which, of course, does not
rotate.

Fig. 30
The governor is driven by the lower gear bolted to the fuel injection
pump camshaft.
The control lever has been removed from its shaft in the governor
housing and set in place to show how it is positioned.
Fig. 31Looking closer, we can see (from right to left) the drive gear ,
flyweights , spring, spring seats, control lever and the collar and bolt
which connects to the rack. The purpose of the collar is explained
later.
Fig. 32
This governor cross section illustrates: (1) lever, (2) spring seat, (3)
spring, (4) spring seat and thrust bearing and (5) flyweight
assembly.
The arrows indicate drive gear rotation and rack movement.
Fig. 33Two adjusting screws limit the travel of the governor control lever
between LOW IDLE position and the HIGH IDLE position.
The low idle stop and high idle stop are simply minimum and
maximum engine rpm settings with no load on the engine.

Fig. 34
The high and low idle adjusting screws are located under the cover
on the governor.
Fig. 35
Notice that the holes in the cover are shaped to lock the screws and
prevent them from turning after they are adjusted.
Fig. 36The operators control is positioned at the desired governor setting:
low idle, high idle or fuel off.

Fig. 37
When the lever in the governor is in the LOW IDLE position, a
spring loaded plunger in the lever assembly contacts the low idle
stop of the adjusting screw.
Fig. 38When the lever in the governor is in the HIGH IDLE position, the
lever contacts the high idle adjusting screw.

Fig. 39
To shut the engine down, the governor control is moved full forward
– past . . . .
Fig. 40. . . the low idle stop. It is necessary to force the plunger over the
shoulder on the low idle screw . . .

Fig. 41
. . .to move the rack to the FUEL OFF position.
Fig. 42Looking, again, at the governor cross section see
(1) the high idle adjusting screw and
(2) the low idle adjusting screw. The lever is against the HIGH IDLE screw.
The low idle and high idle screws, then limit minimum and
maximum engine rpm with no load on the engine. What limits
engine power output when the engine is fully loaded?
Fig. 43
A collar and stop bar limit rack travel and, therefore, the power
output. The collar is secured by a bolt connecting the rack linkage.
The stop bar is mounted in the governor housing. With the rack
moved to the FULL LOAD position, the collar just contacts the stop
bar.
Fig. 44
When our engine is operating with the governor at high idle (1) and
picks up a load, the speed decreases, flyweight centrifugal force
lessens, and the spring moves the rack to give the engine more fuel
increasing power. The collar (2) and stop bar (3) limit the distance
the spring can move the rack. As the collar contacts the stop bar,
full load position is reached. This limits the fuel delivered to the
engine so as not to exceed design limitations.
Fig. 45
Returning to the governor cross section, note the location of the:
(1) collar,
(2) stop bar,
(3) bolt and
(4) rack.
Like other diesel engine components, the governor must be
lubricated for long life. Let’s look at a governor lubrication system
schematic.
Fig. 46
The governor is lubricated by the engine lubricating system. Oil
from the diesel engine oil manifold is directed to the governor drive
bearing. All other governor parts are lubricated by splash.
The oil drains from the governor, through the fuel injection pump
housing, back to the engine crankcase.
Fig. 47
In summary, we have discussed the mechanical governor’s primary
components and principle of operation. Remember a governor has
two basic mechanisms: the speed measuring mechanism and the
fuel changing mechanism.
Fig. 48In our cross section we located the lever, spring, spring seats,
flyweights, thrust bearing, drive gears and rack. We also discussed
the high and low idle settings and the full load stop.
At the beginning of this lesson we warned: NEVER OPERATE A
DIESEL ENGINE WITHOUT A GOVERNOR CONTROLLING
IT. Why are governors so important to a diesel engine?
Fig. 49
Note: The instructor should make clear we are not saying
gasoline engines never have a governor. Some
gasoline engines use a governor for the same reasons as
a diesel: to control engine speed and to regulate engine power output.
First, gasoline engines are self-limiting. Engine speed is controlled
by a butterfly valve in the intake manifold which limits the air
supply Limiting the amount of air taken in for combustion, limits
engine speed.
Fig. 50
Diesel engines, however, are not self-limiting. Engine air intake is
not limited, and the cylinders always have more air than is needed
to support combustion. The amount of fuel injected into the
cylinders controls engine speed.
Fig. 51
And, as the fuel is injected directly into the cylinders rather than
into the air intake manifold, engine response is immediate. This,
resulting greater power stroke, adds up to very rapid acceleration.
As we said earlier, diesel engines can accelerate at a rate of more
than 2000 revolutions per second. Because of this rapid
acceleration, manual control is difficult, if not impossible.
Fig. 52NEVER OPERATE A DIESEL ENGINE WITHOUT A
GOVERNOR CONTROLLING IT.

Fig. 53
At this point, we have built up the basic diesel mechanical governor.
This governor works fine on engines whose engine speed is held
fairly constant and the governor is controlled by hand. However, on
other engines, the force needed to compress the governor spring or
to move the rack -just operating the governor – could be very tiring
to the operator.
Fig. 54With the servo-mechanical governor, the work operation of
compressing the governor spring is done with engine oil pressure.

Fig. 55
With the hydraulic governor, the work operation of moving the fuel
injection pump rack is done with engine oil pressure.
These governors are discussed in . . . .
Fig. 56. . . . Meeting Guide 60, “Servo Mechanical Governors.”

Fig. 57

 

Governor

September 8, 2011
Diesel engine speed is controlled solely by the amount of fuel injected into the engine by the injectors. Because a diesel engine is not self-speed-limiting, it requires not only a means of changing engine speed (throttle control) but also a means of maintaining the desired speed. The governor provides the engine with the feedback mechanism to change speed as needed and to maintain a speed once reached.

A governor is essentially a speed-sensitive device, designed to maintain a constant engine speed regardless of load variation. Since all governors used on diesel engines control engine speed through the regulation of the quantity of fuel delivered to the cylinders, these governors may be classified as speed-regulating governors. As with the engines themselves there are many types and variations of governors. In this module, only the common mechanical-hydraulic type governor will be reviewed.
The major function of the governor is determined by the application of the engine. In an engine that is required to come up and run at only a single speed regardless of load, the governor is called a constant-speed type governor. If the engine is manually controlled, or controlled by an outside device with engine speed being controlled over a range, the governor is called a variable speed type governor. If the engine governor is designed to keep the engine speed above a minimum and below a maximum, then the governor is a speed-limiting type. The last category of governor is the load limiting type. This type of governor limits fuel to ensure that the engine is not loaded above a specified limit. Note that many governors act to perform several of these functions simultaneously.

Operation of a Governor
The following is an explanation of the operation of a constant speed, hydraulically compensated governor using the Woodward brand governor as an example. The principles involved are common in any mechanical and hydraulic governor.

The Woodward speed governor operates the diesel engine fuel racks to ensure a constant engine speed is maintained at any load. The governor is a mechanical-hydraulic type governor and receives its supply of oil from the engine lubricating system. This means that a loss of lube oil pressure will cut off the supply of oil to the governor and cause the governor to shut down the engine. This provides the engine with a built-in shutdown device to protect the engine in the event of loss of lubricating oil pressure.

Simplified Operation of the Governor
The governor controls the fuel rack position through a combined action of the hydraulic piston and a set of mechanical flyweights, which are driven by the engine blower shaft.

Figure 28 provides an illustration of a functional diagram of a mechanical-hydraulic
governor. The position of the flyweights is determined by the speed of the engine. As
the engine speeds up or down, the weights move in or out. The movement of the
flyweights, due to a change in engine speed, moves a small piston (pilot valve) in the
governor’s hydraulic system. This motion adjusts flow of hydraulic fluid to a large
hydraulic piston (servo-motor piston). The large hydraulic piston is linked to the fuel
rack and its motion resets the fuel rack for increased/decreased fuel.


Fig 28 simplified Mechanical-Hydraulic Governor

Detailed Operation of the Governor
With the engine operating, oil from the engine lubrication system is supplied to the
governor pump gears, as illustrated in Figure 29. The pump gears raise the oil pressure to a value determined by the spring relief valve. The oil pressure is maintained in the annular space between the undercut portion of the pilot valve plunger and the bore in the pilot valve bushing. For any given speed setting, the spring speeder exerts a force that is opposed by the centrifugal force of the revolving flyweights. When the two forces are equal, the control land on the pilot valve plunger covers the lower ports in the pilot valve bushing.


Fig 29 Cutway of Woodward Governor

Under these conditions, equal oil pressures are maintained on both sides of the buffer piston and tension on the two buffer springs is equal. Also, the oil pressure is equal on both sides of the receiving compensating land of the pilot valve plunger due to oil passing through the compensating needle valve. Thus, the hydraulic system is in balance, and the engine speed remains constant.

When the engine load increases, the engine starts to slow down in speed. The reduction in engine speed will be sensed by the governor flyweights. The flyweights are forced inward (by the spring), thus lowering the pilot valve plunger (again, due to the downward spring force). Oil under pressure will be admitted under the servo-motor piston (topside of the buffer piston) causing it to rise. This upward motion of the servo-motor piston will be transmitted through the terminal lever to the fuel racks, thus increasing the amount o f fuel injected into the engine. The oil that forces the servo-motor piston upward also forces the buffer piston upward because the oil pressure on each side of the piston is unequal.

This upward motion of the piston compresses the upper buffer spring and relieves the pressure on the lower buffer spring.

The oil cavities above and below the buffer piston are common to the receiving
compensating land on the pilot valve plunger. Because the higher pressure is below the compensating land, the pilot valve plunger is forced upward, recentering the flyweights and causing the control land of the pilot valve to close off the regulating port. Thus, the upward movement of the servo-motor piston stops when it has moved far enough to make the necessary fuel correction.

Oil passing through the compensating needle valve slowly equalizes the pressures above and below the buffer piston, thus allowing the buffer piston to return to the center position, which in turn equalizes the pressure above and below the receiving
compensating land. The pilot valve plunger then moves to its central position and the
engine speed returns to its original setting because there is no longer any excessive
outward force on the flyweights.

The action of the flyweights and the hydraulic feedback mechanism produces stable
engine operation by permitting the governor to move instantaneously in response to the load change and to make the necessary fuel adjustment to maintain the initial engine speed.

SKYACTIV TECHNOLOGY

August 23, 2011

01-2012-Mazda3-Skyactiv-Image-PETROL ENGINE-AUTOMATIC TRANSMISSION

Highlights of the SKYACTIV technologies:

  • SKYACTIV-G: a next-generation highly-efficient direct-injection gasoline engine with the world’s highest compression ratio of 14.0:1
  • SKYACTIV-D: a next-generation clean diesel engine with the world’s lowest compression ratio of 14.0:1
  • SKYACTIV-Drive: a next-generation highly-efficient automatic transmission
  • A next-generation manual transmission with a light shift feel, compact size and significantly reduced weight
  • A next-generation lightweight, highly-rigid body with outstanding crash safety performance
  • A next-generation high-performance lightweight chassis that balances precise handling with a comfortable ride


– First product to be equipped with SKYACTIV technology will be a Mazda Demio featuring an improved, fuel-efficient, next-generation direct-injection engine that achieves fuel economy of 30 km/L.

01-inline-skyactiv-technologies-chASSIS DESIGN-BODY DESIGN-DRIVE DESIGN-DIRECT INJECTION GASOLINE ENGINE


Overview of the SKYACTIV technologies

1. SKYACTIV-G
A next-generation highly-efficient direct-injection gasoline engine that achieves the world’s highest gasoline engine compression ratio of 14.0:1 with no abnormal combustion (knocking)
  • The world’s first gasoline engine for mass production vehicles to achieve a high compression ratio of 14.0:1
  • Significantly improved engine efficiency thanks to the high compression combustion, resulting in 15 percent increases in fuel efficiency and torque
  • Improved everyday driving thanks to increased torque at low- to mid-engine speeds
  • A 4-2-1 exhaust system, cavity pistons, multi hole injectors and other innovations enable the high compression ratio
2. SKYACTIV-D
A next-generation clean diesel engine that will meet global emissions regulations without expensive NOx after treatments — urea selective catalytic reduction (SCR) or a Lean NOx Trap (LNT) — thanks to the world’s lowest diesel engine compression ratio of 14.0:1
  • 20 percent better fuel efficiency thanks to the low compression ratio of 14.0:1
  • A new two-stage turbocharger realizes smooth and linear response from low to high engine speeds, and greatly increases low- and high-end torque (up to the 5,200 rpm rev limit)
  • Complies with global emissions regulations (Euro6 in Europe, Tier2Bin5 in North America, and the Post New Long-Term Regulations in Japan), without expensive NOx after treatment
3. SKYACTIV-Drive
A next-generation highly efficient automatic transmission that achieves excellent torque transfer efficiency through a wider lock-up range and features the best attributes of all transmission types
  • Combines all the advantages of conventional automatic transmissions, continuously variable transmissions, and dual clutch transmissions
  • A dramatically widened lock-up range improves torque transfer efficiency and realizes a direct driving feel that is equivalent to a manual transmission
  • A 4-to-7 percent improvement in fuel economy compared to the current transmission
4. SKYACTIV-MT
A light and compact next-generation manual transmission with crisp and light shift feel like that of a sports car, optimized for a front-engine front-wheel-drive layout
  • Short stroke and light shift feel
  • Significantly reduced size and weight due to a revised structure
  • More efficient vehicle packaging thanks to its compact size
  • Improved fuel economy due to reduced internal friction
5. SKYACTIV-Body
A next-generation lightweight, highly-rigid body with outstanding crash safety performance and high rigidity for greater driving pleasure
  • High rigidity and lightness (8 percent lighter, 30 percent more rigid)
  • Outstanding crash safety performance and lightness
  • A “straight structure” in which each part of the frame is configured to be as straight as possible. Additionally, a “continuous framework” approach was adopted in which each section functions in a coordinated manner with the other connecting sections
  • Reduced weight through optimized bonding methods and expanded use of high-tensile steel
6. SKYACTIV-Chassis
A next-generation high-performance lightweight chassis that balances precise handling with a comfortable ride feel to realize driving pleasure
  • Newly developed front strut and rear multilink suspension ensures high rigidity and lightness (The entire chassis is 14 percent lighter than the previous version.)
  • Mid-speed agility and high-speed stability — enhanced ride quality at all speeds achieved through a revision of the functional allocation of all the suspension and steering components

MECHANICAL ENGG QUESTIONS-2

August 22, 2011

01-interview-interview questions-placement paper-interview questions and answers-mechanical interview tips-interview skills-interview preparation

  • Different between technology & engineering?

Engineering is application of science. Technology shows various methods of Engineering. A bridge can be made by using beams to bear the load,by an arc or by hanging in a cable; all shows different technology but comes under civil engineering and science applied is laws of force/load distribution.

  • how a diesel engine works in generator?

Diesel engine is a prime mover,for a generator,pump,and for vehicles etc.generator is connected to engine by shaft.mostly in thermal power plat ,there is an engine is used to drive generator to generate power.

  • WHAT IS THE OTHER NAME OF MICROMETER & VERNIER CALLIPER

Micrometer’s other name is Screw Gauze & Vernier caliper’s other name is slide caliper.

  • What is flashpoint?

Flash point: the lowest temperature at which the vapor of a combustible liquid can be ignited in air.

  • what is basic difference between impulse turbine and reaction turbine?

In impulse turbine, jet is used to create impulse on blades
which rotates the turbine and in reaction turbine, no jet
is used pressure energy is converted into kinetic energy.

In impulse turbine fluid enter& leave with same energy ,but in reaction turbine fluid enter with pressure energy&
leaves with kinetic energy

In impulse turbine all the pressure drops in nozzle only &
in reaction turbine pressure drops both fixed & moving
blades.the difference is due to blade profiles.

  • What is the need for drafting?

Drafting is the allowance give to casting process.it also used to remove the casting from mould without damage of
corners.

  • what is the difference between BSP thread and BSW thread?

The British Standard Pipe thread (BSP thread) is a family
of standard screw thread types that has been adopted
internationally for interconnecting and sealing pipe ends
by mating an external (male) with an internal (female) thread.
British Standard Whitworth (BSW) is one of a number of
imperial unit based screw thread standards which use the
same bolt heads and nut hexagonal sizes.

  • What is refrigerant?

Any substance that transfers heat from one place to another,
creating a cooling effect. water is the refrigerant in absorption machines.

  • The amount of carbon present in Cast Iron

Carbon is basically present in the form of cementite in cast iron.Its percentage lies in the range of 2.03-6.67(% by weight of cementite for Cast Iron.If the amount is less than the above range than it is stainless steel.

  • What are the loads considered when designing the Nut and Bolts?

Shear Loads & crushing loads

  • what is the effect of reheat on rankine cycle? 1.efficiency increases 2.work output increases 3. both 4. none of these.

1.Efficiency increases.

this prevents the vapor from condensing during its expansion which can seriously damage the turbine blades, and improves the efficiency of the cycle, as more of the heat flow into the cycle occurs at higher temperature.