2] Comparison of radial-ply and cross-ply tubes

Radial ply Cross ply

In radial ply type, the cords of tyre run in radial In cross ply type, alternate layers of cords run in
direction opposite direction

The cord ply are woven in radial direction of tyre The cord ply are woven at angles of 30-40 degrees
axis to the tyre axis

Radial tyre are provided with breaker strip, thus a There is no breaker strip in this tyre. Thus
continuous flat contact is possible with the road continuous grip with road surface is not possible
surface

This tyre has low rolling resistance, thus better fuell The cross ply has more rolling resistance as
efficiency compared to radial ply

This tyre provides better directional stability This tyre has wobbling characteristics

This tyre has greater sidewall flexibility and treads sidewall flexibility and treads stiffness is lesser as
stiffness compared to radial ply type

U.10] Explain tubed tyres.

 Figure shows a simplified form the cross section

of such a tyre. It consists of two main parts, viz. the
carcass and the tread.
 The carcass is the basic structure taking mainly
the various loads and consists of a number of plies
wound in a particular fashion from the cords of
rayon or any other suitable material.
 In order to prevent the tyre from being thrown off
the rim, the plies are attached to two rings of high
tension steel wire. These rings are made to fit snugly
against wheel rim thereby anchoring the tyre to the
rim. These rings are called beads.
 The tread is the part of the tyre which contacts the
road surface when the wheel rolls. It is generally
made of synthetic rubber.
 Between the head and the tread the outer rubber covering of the carcass is called side
wall. The sidewalls are designed to flex and bend without cracking when subjected to
continuous deflection while running. In other words, the sidewall material must have
high fatigue strength.
  At the inner edges, beads are formed by reinforcing with steel wires. This provides the
tyre with strong shoulders for bearing against the wheel rim. All plies are tied to the
beads which prevent any change of shape.
 Inside the tyre, there is a tube which contains the air under pressure. The tube being
very thin and flexible, takes up the shape of the tyre cover when inflated. A valve stem
is attached to the tube for inflating or deflating the same.

U.11] Explain tubeless tyres.

This type of tyre does not need a separate tube; instead the air under pressure is filled in the
tyre for which purpose a non-return valve is fitted to the rim. The inner construction of the tyre
is almost same as that of tube tyre, except that it is lined on inside with a special air-retaining
liner.
The tubeless tyres possess following advantages over the conventional tubed tyres.
1. Temporary puncture repairs are made with out removing the wheel.a rubber plug is
inserted at the place of puncture.
2. Air is retained for longer period even after punctured.
3. Tubless tyres are lighter in weight and cooles faster.
4. Tubless tyres imparts more resistance to impact load.
5. Better air seeling qualities are obtain.
6. It is simple in assemble only tyre has to be fitted on rim
U.1] Explain the working of electronic ignition system with a neat sketch.

 In an electronic ignition system a timer is employed in the distributor.

 Timer sends the electrical pulses to an electric Control Unit [ECU] which switches off
the flow of current to the primary winding.
 As a result, a high voltage is induced in the secondary winding which is then distributed
to the spark plugs.
 The ECU later switches on the flow of current to the primary circuit so that the primary
circuit can be built up for the next cycle.
 The timer may be pulse generator or Hall effect sensor.
 Other than this, the electronic ignition system works similar to conventional type.
 The other few types of commonly used timers in electronic ignition system are pulse
generator, Hall effect switch, optical switch and capacitor discharge method.

U.2] Explain the working of Battery ignition system with a neat sketch.
  Figure shows Battery ignition system for a 4 cylinder engine. A battery of 12 volts is
generally employed.
 The battery, primary winding of ignition coil, condenser and the contact breaker form
the primary circuit.
 Secondary winding of the ignition coil, distributor and the spark plugs forms the
secondary circuit.
 When the ignition switch is closed, electric current will flow through primary winding
of ignition coil. As soon as the contact breaker is closed which setting up primary
magnetic flux.
 The contact breaker cam which is revolving continuously opens the contact breaker.
Immediately the primary magnetic field gets collapse thereby inducing a very high
voltage in secondary winding.
 This high voltage then passes to a distributor. It connects the spark plugs of the
cylinders in rotation depending upon the firing order of the engine causing a high
intensity of spark across the gap thereby ignition of the air fuel mixture takes place in
all the cylinders.
 The capacitor increases the rate of collapse of primary field thereby helping to induce
higher voltage in secondary winding.

U.3] Explain the working of Magneto ignition system with a neat sketch.
  The Magneto ignition system works on the same principle as that of the battery ignition
system, except that no battery is required, as the magneto acts as its own generator.
 It consists of either rotating magnets in fixed coils, or rotating coils in fixed magnets.
 The current produced by the magneto is made to flow to the induction coil which works
in the same as that of battery ignition system.
 This high voltage current is then made to flow to the distributor, which connects the
spark plugs in rotation depending upon the firing order of the engine.
 This type of the ignition system are used in small SI engines such as scooters, motor
cycles etc.

U.4] Explain Starting system.

 The starting system is used to start the engine.

 It mainly consists of a plunger, contact disc, pull-in-winding, terminal and connecting
cables. The switch is connected between the starting motor and the battery. The current
from the battery passes through the pull-in-winding to form a strong electromagnet.
 When the switch is on, the current flows from the battery to the pull-in-winding. The
electromagnet attracts the plunger against the spring, which causes the two terminals
connected by the contact disc. This makes the circuit complete between the battery and
the starting motor. Now the current flows directly from the motor.
 When the switch is off, the circuit gets disconnected. The current flow stops and the
spring moves the plunger and the contact disc back to disconnecting the starting motor
from the battery.

U.2] Explain the working of AC Mechanical pump with a neat sketch.

Fig show AC mechanical pump. It consists of a diaphragm, a cylindrical chamber with inlet,
outlet, a strainer and suction and delivery valve. As the
cam rotates it operates the rocker arm to move up, it
pulls the diaphragm down, causing a vacuum in the
chamber. This makes the suction valve to open and the
petrol enters the chamber. Under suction the delivery
valve is kept closed. When the cam releases the rocker
arm. The diaphragm moves up to its normal position
under spring pressure. This creates a pressure in the
fuel chamber and forces the fuel out through the
delivery valve. Under this condition the suction valves
is kept closed and the delivery valve is in open
condition.
When the fuel pressure in the pump increases it compresses the diaphragm spring and rocker
arm spring which separate the rocker arm from the eccentric. This although the cam is running
the pump is not operated till the fuel pressure decreases in the pump. In this manner the fuel
supply to the carburetor is regulated in accordance with its end.
U.9] Explain water cooling system with sketch.

Water cooling system mainly

consists of :
(a) Radiator,
(b) Thermostat valve,
(c) Water pump,
(d) Fan,
(e) Water Jackets, and
(f) Antifreeze mixtures.
Radiator
 It mainly consists of an upper
tank and lower tank and between them is a core.
 When the water is flowing down through the radiator core, it is cooled partially by the fan
which blows air and partially by the air flow developed by the forward motion of the vehicle.
 It is to be noted that radiators are generally made out of copper and brass and their joints
are made by soldering
Thermostat Valve
 It is a valve which prevents flow of water from the engine to radiator, so that engine readily
reaches to its maximum efficient operating temperature.
 After attaining maximum efficient operating temperature, it automatically begins
functioning. Generally, it prevents the water below 70°C.
Water Pump
 It is used to pump the circulating water.
 The pump is driven by means of engine output shaft only through belts. When it is driven
water will be pumped.
Fan
 It is driven by the engine output shaft through same belt that drives the pump.
 It is provided behind the radiator and it blows air over the radiator for cooling purpose.
Water Jackets
 Cooling water jackets are provided around the cylinder, cylinder head, valve seats and any
hot parts which are to be cooled.
 Heat generated in the engine cylinder, conducted through the cylinder walls to the jackets.
 The water flowing through the jackets absorbs this heat and gets hot. This hot water will
then be cooled in the radiator.
Antifreeze Mixture
 In western countries if the water used in the radiator freezes because of cold climates, then
ice formed has more volume and produces cracks in the cylinder blocks, pipes, and radiator.
So, to prevent freezing antifreeze mixtures or solutions are added in the cooling water

U.7] Explain DTSI System.

Digital Twin Spark ignition engine has two Spark plugs located at opposite ends of the combustion
chamber and hence fast and efficient combustion is obtained. The benefits of this efficient
combustion process can be felt in terms of better fuel efficiency and lower emissions. The ignition
system on the Twin spark is a digital system with static spark advance and no moving parts subject to
wear. It is mapped by the integrated digital electronic control box which also handles fuel injection
and valve timing. It features two plugs per cylinder.

Main characteristics
 Digital electronic ignition with two plugs per cylinder
and two ignition distributors.
 Twin overhead cams with camshaft timing variation.
 Injection fuel feed with integrated electronic twin spark
ignition.
 A high specific power.
 Compact design and Superior balance.
Advantages
 Less vibrations and noise
 Long life of the engine parts such as piston rings and valve stem.
 Decrease in the specific fuel consumption
 No over heating
 Increase the Thermal Efficiency of the Engine & even bear high loads on it.
 Better starting of engine even in winter season & cold climatic conditions or at very low
temperatures because of increased Compression ratio.
 Because of twin Sparks the diameter of the flame increases rapidly that would result in
instantaneous burning of fuels. Thus force exerted on the piston would increase leading to
better work output.
Disadvantages
 There is high NOx emission
 If one spark plug get damaged then we have to replace both
 The cost is relatively more
Applications
 In India Bajaj has patented for dts-i technology.
 At present platina, xcd125, 135, discover150, pulsar135, 150, 180, 200, 220 etc. are using
the
dts-i(digital twin spark ignition system).

U.8] Explain CRDI (Common Rail Direct Injection) System

 In this a single injection pump with

injector is employed in each cylinder.
 The unit injectors are operated by rocker
arms and springs similar to engine valves.
 A linkage connects the control racks of all
the unit injectors, so that fuel injection in all
the cylinders may be equal and
simultaneously controlled.
 The fuel is taken from the fuel tank by the
feed pump and is supplied at low pressure
through a filter, to all the unit injectors.
 This avoids the high pressure fuel lines necessary in the individual pump system.
 Any excess fuel from the relief valve is returned to the fuel tank.