AUTOMOBILE ENGINES

The working of an automobile engine follows the same principle as an internal combustion engine. Air, from outside, enters the engine through the air cleaner and reaches the throttle plate.
The pedal in your car is the control for the amount of air that you would want to be taken in, and you control it by pressing on this gas pedal.
The air is then distributed through the intake manifold of the cylinders.

At some point fuel is injected into the air stream, and the mixture vaporizes and is drawn into the cylinders as they start their intake stroke.

This way, when the cylinder has reached its bottom, it has drawn in sufficient mixture. As it moves up, compressing the mixture, the spark plug ignites the mixture, and as the powerful gas formed expands, it pushes the cylinder to the bottom with the cylinder once again drawing in the mixture.

In designing automobile engines, you need to be a specialist in automobile engineering.
The consideration that is taken while designing such an engine is whether it should be a carburetor or a diesel one. carburetor engines are most commonly found in passenger cars and low capacity trucks, while trucks with a capacity over two tons are fitted with diesel engines, including dump trucks, trailer tractors and bus.

Increasingly the medium and low-capacity vehicles are being fitted with diesel engines, since the fuel consumption of these engines are 30% to 50% lower than the carburetor engines.
Diesel engines not only cost more, but maintenance is much more expensive than the other type of engine. Diesels require more metal parts per kilowatt.
The critical parts of diesel engines are made of alloy steel, and the fuel injection system is much more expensive than carburetor engines.

However, the cost of manufacturing carburetor engines has increased with the use of higher mechanical grade components, considering the thermal loads of the material used. At the same time the use of high alloys and increase in production costs have contributed to the higher price of such engines.

There is a sharp rise in using aluminum alloys in design of carburetor engines in passenger cars, and with the use of high octane petrol, the cost of operation of these cars have come down extensively. Using alloy steel in constructing the engine body and other parts of the engine, makes the car lighter and hence fuel consumption goes down substantially.

The main parts that are made of high steel alloy are the main casting of the engine, the cylinder head, water and oil pumps, oil filter housing, end covers of the generator and starter, and the intake pipes. It has been observed that by using high steel alloys, the weight of the car is reduced by 35%.

The power per liter, per unit of piston area, and the brake effective pressure are 6% to 8% lower in air-cooled engines, compared to engines having liquid cooling mechanism. This is due to the fact that in engines with liquid cooling there are great losses in cylinder charging caused by the high temperature in pipes, ducts in the head, cylinder walls and head, etc.

The size of air cooled engines are much bigger than the engines with liquid cooling having the same capacity, and this is because the cylinder axes difference is larger in air-cooled engines. Taking account of the radiator dimensions, if both engines are compared, the air-cooled engine will vary slightly with its height a little longer than or approximately the same length as the water-cooled engine. As far as the width and the height is concerned both engines are about the same.

The auxiliary units of the feed and ignition, and generator and starter systems are a bit difficult to fit on the body of the air-cooled engines, because of the presence of hoods and having a danger of over-heating.

Design of Screw Conveyor

The size of screw conveyor depends on two factors

1. The capacity of the conveyor

2. The lump size of the material to be conveyed (Maximum dimensions of the particle)

Usually there are three ranges of lump sizes which are considered for selection of screw size. These are:

· A mixture of lumps and fines in which not more than 10% are lumps ranging from maximum size to one half of the maximum, and 90% are lumps smaller than one half of the maximum size.

· A mixture of lump and fines in which not more than 25% are lumps ranging from the maximum size to one half of the maximum, and 75% are lumps smaller than one half of the maximum size.

· A mixture of lump only in which 95% or more are lumps ranging from maximum size to one half of the maximum size and 5% or less are lumps less than one tenth of the maximum size.

The allowable size of a lump in a screw conveyor is a function of the radial clearance between the outside diameter of the central pipe and the radius of the inside of the screw trough, as well as the proportion of the lumps in the mixture.

The lump size of the material affects the selection of screw diameter which should be at least 12 times larger than the lump size of a sized material and four times larger than the largest lumps of an un-sized material.

Example, if screw diameter is 250mm means radial clearance is 105mm, & Maximum lump size is 60mm of 10% lumps.

Capacity of Screw Conveyor:

 

The capacity of a screw conveyor depends on the screw diameter, screw pitch, speed of the screw and the loading efficiency of the cross sectional area of the screw. The capacity of a screw conveyor with a continuous screw:

Q = V. ρ

Q = 60. (π/4).D².S.n.ψ.ρ.C

Where,

Q = capacity of a screw conveyor

V = Volumetric capacity in m³/Hr

ρ = Bulk density of the material, kg/m³

D = Nominal diameter of Screw in m

S = Screw pitch in m

N = RPM of screw

Ψ = Loading efficiency of the screw

C = Factor to take into account the inclination of the conveyor

 

Screw Pitch:

Commonly the screw pitch is taken equal to the diameter of the screw D. However it may range 0.75 – 1.0 times the diameter of the screw.

 

 

 

 

Screw Diameter:

 

Nominal Size D	Trough height from center of screw shaft to upper edge of the trough	Trough width C	Thickness of Tough	Tubular shaft (d1 * Thickness)	Outside diameter of solid shaft	Coupling diameter of shaft
Heavy Duty	Medium Duty	Light Duty
100	63	120	–	2	1.6	33.7*2.5	30	25
125	75	145	–	2	1.6	33.7*2.5	30	25
160	90	180	5	3.15	1.6	42.4*2.5	35	40
200	112	220	5	3.15	2	48.3*3.5	40	40
250	140	270	5	3.15	2	60.3*4	50	50
315	180	335	5	3.15	–	76.1*5	60	50
400	224	420	5	3.15	–	76.1*5	60	75
500	280	530	5	3.15	–	88.9*5	70	75

RPM of Screw:

The usual range of RPM of screw is 10 to 165. It depends on the diameter of screw and the type of material (Max RPM of screw conveyor is 165)

Loading efficiency:

The value of loading efficiency should be taken large for materials which are free flowing and non abrasive, while for materials which are not free flowing and or abrasive in nature, the value should be taken low:

Ψ = 0.12 to 0.15 for abrasive material

= 0.25 to 0.3 for mildly abrasive material

= 0.4 to 0.45 for non abrasive free flowing materials

Inclination Factor:

The inclination factor C is determined by the angle of screw conveyor with the horizontal.

 

Angle of screw with the horizontal	0°	5°	10°	15°	20°
Value of factor C	1	0.9	0.8	0.7	0.65

Types of screw flight:

The screw of the conveyor may be right hand or left hand, the right hand type being the usual design. The threads of the screw may be single, double or triple.

The flight of the screws may be made in either of the two ways:

1. As Helicoids

2. As Sectional flight

Helicoids Flight:

They are formed from a flat bar or strip into a continues helix. The threads are thinner at the outer edge and thicker at the inner edge.

Sectional flights:

Sectional flights are formed from a flat disc and the thickness of the thread is uniform throughout. A continuous helix is made by joining a number of sectional flights together on a piece of pipe and butt welded them. Various styles of screw flights are in use, depending on the service required.

Some of the typical configurations are:

1. Short pitch or continuous flight:

If the conveyor is required to handle dry granular or powdered materials that do not pack, this style of flight may be selected. It is of regular construction and recommended for inclined conveyors having a slope of 20 or more, including vertical conveyors. This style is extensively used as feeder screw.

2. Ribbon flight:

If the conveyor is to handle lumpy, clinging, sticky, gummy or viscous substances, this type flight may be selected. It consists of continuous helical flight formed from steel bar and secured to the pipe by supporting lugs.

3. Cut flight:

In this type of flight screws have notches cut in the periphery of the flight. These notches supplement the conveying with moderate mixing action. They are recommended for conveyors required to handle light, fine, granular or flaky materials.

4. Cut and folded flights:

This type of flight is characterized by notches as in cut flight, together with folded segments. This type of flight creates agitation and aeration resulting in better mixing. This type of flight is used to handle light or medium weight materials having fine, granular or flaky materials.

5. Some screw conveyors have cut flight with paddles mounted at regular intervals. The paddles counteract the flow of material past the flight resulting in greater agitation and mixing.

6. Sometimes screws are made of stainless steel to suit special requirements, like the sanitation requirements for handling food, drugs and other hygienic materials.

Some posts need no title…!!

It’s 12th august , A Friday ,The day suddenly i took the task of completing my tour memoirs..Don’t know why suddenly i took that thing…!!

I’ve tried so many times but without completion..!

I know i’m pretty good at taking initiations and taking first leap…

But hell is that i can’t live upto expectations when it comes to execution..!!

I do remember a person when i talk about the start of proceedings for Industrial tour..!!
That day
In December,2010… i think

I was seriously googling for some books (of course i don’t read’em…But i used to maintain a good collection of E-Books…!!)

I got a message on my Gtalk Gadget ” Do You know Civil people are booking their train tickets for their Industrial tour..!!”

…

oh is it…

okay lets c…

some one will take a forward leap in our class lets follow him(There is a reason for not including HER here…!!)…

after few days @ After Lunch Discussion
I had a discussion regarding this tour with Abbas ,Sasidhar,Mahendra…

Few people who got interest in arranging such type of events…

I’m fortunate have such a bunch of good organizers…

People like them took such tasks with huge responsibility…

and they are really good team players…!!

i really love working with them.!

There are people who bank upon the people behind curtain…

they don’t do much work but they do indulge in things at eleventh hour ..!!

These people should be appreciated when compared to those people who crack jokes on The Organizers…!!

at last after so many days we have finalized the places and dates

and the faculty ,permissions, Money etc…

But still there is one task to be completed ” making the total count to 40″

While trying to reach 40

we came across some Strange situations and some PECULIAR people…!

One said ” My grand pa is seriously ill”

can’t comment on such reasons…

the person’s been perfectly polite i(we) cudn’t question Honesty…!!

One couldn’t blame other people’s family responsibilities..!!

Another guy

the most awful case

” I tried to call and convince my dad to permit me…

and the network people saying that it was wrong dialed…

Suddenly i remembered that I FORGOT MY DAD’S Phone Number..”

Dumbstruck at the very moment….

Thank god i’m still alive….

And this thing happened to our beloved XCr suddenly offered his helping hand and we were delighted…!!

I thought owing to cold war between us

they may remain as audience…

but no

they came forward…!!

Another guy

pirated emotions…

I was cursed with the ability to guess intentions of people from their eyes….

Lips can lie while eyes can’t…

i cant guess exactly but i can suspect mismatch between words and expressions…!!

Anyway after so many Adventures and differentiations The tour started ..!!

I have had written till the PRASHATHI XPRESS dropeed us at B’lore-Yeshwanthpura Rail station @12 noon…!!

A Guy from the travel company came and received us ….Soon we packed our luggage, baggage into the luxury bus that had been arranged for us …!!

Started off to The Central Manufacturing Technology Insti(CMTI), CVRaman Nagar.!

JIB CRANE

Jib crane have the following motions:

1. Hoisting motion
2. Derricking or luffing motion
3. Slewing motion
4. Long travel motion

Hoisting motion:

It is used to lift or lower the load. This is usually achieved by steel wire ropes being affixed to a crane hook or a grab hanging from the outer end of the jib. The rope is applied through some receiving arrangement and controlled and operated by a winch system.

Derricking or Luffing motion:

It is imparted to the inclined member or the jib to move in a vertical plane so that the angle of the jib may be changed in order to bring the load line nearer to or further off from the centre of the crane.

Slewing motion:

It is imparted to the whole super structure of the crane including the jib, so that it can turn about a central pivot shaft w.r.t. the non-revolving parts. This motion enables the crane to shift the load line to revolve round the crane.

Long Travel Motion:

It may be required when the whole crane structure has to be shifted to a distant place along a rail track or along a road.

Jib crane consists of an inclined member supported by a rope or any other type of structural member attached to a vertical mast or frame. Load is usually suspended from the outer end of this inclined mast. The outreach of the jib may be fixed or variable. The cranes as a whole may be either fixed or moveable. Various sub-classification of these cranes are possible.

Lifting capacity of such cranes may vary from 1/2 ton to 200 ton and outreach from a few meter to 50 meter. Such cranes find various applications in port area, construction site, and other outdoor works.

For handling general cargo, lifting capacities are usually 1  1/2 ton to  5 ton with maximum outreach of 30 meter. Jib Cranes provided with grabbing facilities have usually a capacity ranging from 3 to 20 tons operating 50 to 100 cycles per hour. Lifting heights may be 30 meters or more.

Jib crane used in ship yards for lifting heavy machinery and equipment, weighing 100 to 300 tons, are usually mounted on pontoons. Frequently these cranes are provided with two main hoisting winches which can be employed singly or together to lift a load. For handling light loads these cranes may have auxiliary arrangement.

Types Of Jib Crane:

Depending on the use, jib cranes are classified into a number of varieties, primarily on the basis of their mountings.

These are:

1. Hand Operated Scotch Derrick Type
2. Wall Mounted Jib crane
3. Portal / Semi-portal cranes of different varieties-Wharf cranes
4. Mobile jib cranes consisting of truck mounted and crawler mounted cranes

Scotch Derrick Type / Wall Cranes:

Wall cranes are used in ware houses for handling light weight and when there is little or no wharf between them and the water front. Slewing or rotational motion of the crane is possible within restricted angle and the motion is slow. Hoisting and lifting speeds are comparable to those of wharf cranes. In some modified version these cranes can have travelling speed along the wall.

Wharf Cranes:

These are used in shipyard and port for handling unit and bulk load. These are usually self propelled balanced level luffing type with full circle slewing motion facility. Wharf cranes may be of different types, depending on the type of structure on which it is mounted.  The choice of structure for mounting depends on site condition.

The principal types of wharf cranes are:

• High pedestal
• Full Portal
• Semi-portal

Portal Cranes:

Portal crane is a fixed or revolving type jib crane mounted on a portal frame fixed in location or arranged to travel along a fixed track of rails at the same level. The portal frame consists essentially of horizontal girders connected at both ends to vertical or inclined member’s having equal lengths.

Semi portal Crane:

Semi portal crane is a fixed or revolving type jib crane mounted on a semi portal frame fixed in location or arranged to travel along a fixed track or rails at different levels. The semi portal frame essentially consists of horizontal girders connected at both ends to vertical or inclined members which constitute a shorter side and a longer side. The shorter members may consist only of the trolley running along the elevated rail.

Mobile crane:

Mobile Crane ( Power Driven ) includes all type of travelling jib cranes, such as truck mounted, crawler mounted, locomotive crane on rails.