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The correct answer is (a) 1

The best I can explain: The pilot injection ALSO called a pure injection which is a short bust of fuel before the main injection during each COMBUSTION cycle is in the RANGE of 1millimeter and 50-millimetercube for FULL load main injection. The injection duration is about 1 to 2milliseconds.

Correct answer is (a) RAIL pressure sensor

To explain: The fuel from the fuel tank is pumped by a low-pressure electric fuel PUMP through a filter, to the HIGH-pressure pump, which builds up the high pressure in the common rail with the HELP of a pressure regulator valve controlled by ECU through a rail pressure sensor.

Right option is (d) Electronic control unit

For explanation: The ECU is an electronic control unit. The ECU has VARIOUS program maps stored in it. The ECU CONTROLS the fuel pressure in the COMMON rail, integrated diagnosis-sensor monitoring and malfunction recognition, and other supplementary FUNCTIONS.

The correct OPTION is (c) Spark plug

Easy EXPLANATION: The ECU takes the reading from the sensor based on the reading the ECU controls the fuel DELIVERY from the electric fuel PUMP with prefilter and send the fuel to the high-pressure pump with a pressure regulator valve and then fuel is sent to the common rail than with the INJECTOR the fuel is injected.

The correct option is (d) 3

Best explanation: The combustion behavior in diesel engines is affected by three variables,which are the TIMING of injection start, duration of injection, and DISCHARGE CURVE which all are individually controlled in a common RAIN FUEL injection system.

Right choice is (a) Pressure limiter

To explain: The fuel pressure in the rail is independent of ENGINE SPEED and the injected fuel quantity. Flow limiters protect the system against the CONSEQUENCES of a potential leak of the INJECTOR. A pressure limiter VALVE guards the system against excess pressure.

The correct option is (d) Alternator speed

To explain I would say: The fuel is injected in the engine COMBUSTION CHAMBER by the injection nozzle of an injector controlled by a solenoid-operated valve. The injector receives its operation signal from ECU. The system PRESSURE, the duration of injection, and the size of the nozzle determine the fuel quantity injected.

The CORRECT answer is (b) HIGH-PRESSURE pump

Easiest explanation: Radial piston pump is an EXAMPLE of a high-pressure pump that generates high pressure in the accumulator, the rail independent of engine speed, and injected fuel quantity. The engine drives the pump through the coupling, gear wheel, chain, or toothed belt.

The CORRECT option is (b) Retarded post ignition mode

The explanation is: After the main injection PHASE, after which post-injection SPURT of fuel is added, which reduces soot emissions. Finally, after UPTO 180 degrees of the crankshaft, a retarded post ignition occurs, which acts as a reducing agent for NOx and increases the exhaust gas temperature for the regeneration of the particulate filter.

Right ANSWER is (b) The common rail injection system

To explain: The common rail injection system, the injection PRESSURE is possible even at low engine speeds which leads to more COMPLETE combustion of the fuel. It ALSO increases the engine torque in the lower engine speed ranges.

Correct choice is (b) SOLENOID valve

To ELABORATE: The fuel injectors PRESENT in the modern common RAIL fuel system are activated by the solenoid valve. Solenoid valves and the fuel pump are electronically controlled. Thus, the common rail serves as the high-pressure reservoir independent of the ENGINE speed.

The CORRECT CHOICE is (a) Spring and lever

The explanation: The idling spring adjustment is provided utilizing a separate spring and lever, the spring tension can be adjusted with an adjusting nut provided. WHEREAS the camshaft, rack, and PINION and gears have no OPERATION in the idling spring.

The correct option is (c) Centrifugal FORCE

Explanation: As the engine speed increases, the centrifugal force DUE to WEIGHTS acts against the spring tension. Once the FORMER exceeds the latter, the weights FLY apart, causing the other ends of the bell crank levers to raise the sleeve.

The CORRECT answer is (c) Accelerator pedal

To elaborate: Accelerator pedal controls the POSITION of the butterfly valve in the venturi UNIT and hence the amount of VACUUM from the inlet manifold,which is applied to the diaphragm via the vacuum pipe. As the diaphragm is connected to the FUEL pump control rack.

The correct option is (b) Governor run-off

The EXPLANATION: The terminology governor run-off is DEFINED as the PERCENTAGE speed change when the control rod is moved by the governor from the MAXIMUM fuel delivery position to the no- fuel delivery position.

The CORRECT option is (b) ENGINE

The best explanation: The two spring-loaded weights are MOUNTED on the governor SHAFT which gets its drive from the engine. At one end, the BELL crank lever carries balls whereas their other ends touch the lower surface of the flange of a sleeve on the governor shaft.

The CORRECT choice is (d) Governor cut-in speed

For explanation: The terminology governor cut-in speed is the speed of the fuel injection pump at which the control rod just starts to move away from the MAXIMUM fuel stop with the ACCELERATOR lever set for maximum OUTPUT.

The CORRECT choice is (a) Control rack

The best explanation: The SPRING tension can be so ADJUSTED as to actuate the control rack for a DECREASE in fuel delivery at some maximum SPEED. Below this maximum speed, the control rack on the fuel injection pump may be directly operated by the driver through accelerator pedal and linkage, with a provision to override the driver control at maximum speed which is limited by the spring tension.

The correct OPTION is (a) Governor

For explanation: The accelerator pedal and the pump CONTROL rack are linked only through the governor. The driver,then, changes spring tension with the help of the accelerator pedal and hence fix the SPEED of the engine in a VEHICLE.

The correct ANSWER is (d) Between governor cut-off speedand governor cut-in speed

The best explanation: Governor OVERRUN is DEFINED as the DIFFERENCE between the governor cut-off speed and the governor cut-in speed. Governor overrun is an important terminology in a governor along with governor hysteresis etc.

Right choice is (d) Glow plug

The explanation is: The pneumatic governor CONSISTS of two main parts, the venturi unit, and the diaphragm unit. The venturi unit is connected to the engine inlet manifold and the diaphragm unit is fitted on the fuel INJECTION PUMP. The two units are connected by a vacuum pipe.

The correct choice is (b) MECHANICAL GOVERNOR

Explanation: In a mechanical governor below this maximum speed, the control rack on the fuel injection PUMP may be directly operated by the driver through accelerator PEDAL and LINKAGE, with a provision to override the driver control at maximum speed which is limited by the amount of spring tension. Such a governor is called the maximum speed governor.

The CORRECT answer is (B) INVERTED hydraulic amplifier

The explanation: A hydraulic governor for example the CAV WORKS on the principle of an inverted hydraulic amplifier wherein a small pressure changes in some part of the system producing in some other part, an opposite change of much greater amplitude.

Right choice is (c) It injects a small amount of fuel

To explain I would SAY: The function of the auxiliary hole drilled in the nozzle BODY is to INJECT a small amount of fuel through its addition hole which is CALLED a pilot injection in an UPSTREAM direction slightly before the main injection.

The correct option is (a) Self-cleaning

For explanation: The PINTLE type of nozzle carries an extension, which produces a hollow cone-type SPRAY. Such nozzle has the ADVANTAGE of being self-cleaning and the advantage of a good nozzle is to atomize the FUEL UNIFORMLY and to maintain proper injection angle and direction.

Correct choice is (c) 15

Easiest explanation: The SINGLE HOLE nozzle has a SPRAY cone angle about 15 degrees and one of the major disadvantages of this nozzle is that they tend to dribble. Besides, their spray angle is too narrow to FACILITATE good mixing UNLESS higher velocities are used.

Correct option is (c) SPARK plug

To explain: The injector mainly consists of the NOZZLE, the.nozzle holder, the adjusting screw which is CONNECTED to the LOCKING nut, spindle, valve, leak-off port, etc whereas there is no spark plug COMPONENT in a fuel injector.

The correct choice is (d) 20

Explanation: In a multi-nozzle INJECTOR the nozzle consist of SEVERAL holes bored in these TIP of the nozzle. The number of while varies from 4 to 18 and the WHOLE angle is about 20 degrees upwards.

Correct option is (a) Pre – combustion

Easy explanation: There are two types of nozzle mainly the hole TYPE and the PINTLE type nozzle whereas the pintle type nozzle is preferred in common ENGINES with pre-combustion chambers and some special SWIRL chambers.

Correct answer is (C) 7-15

For explanation: In pintle TYPE nozzle the rate of injection increasing gradually as the pintle: protrudes further from the nozzle end. The OPENING pressure of the pintle type nozzle varies from 7 to 15MPA which gives more fuel UNIFORMITY.

Correct choice is (B) Truncated cone

Explanation: The PINTLE type nozzle carries an extension, which produces a hollow cone-type spray. The pintle is much longer and is ALSO shaped like a truncated cone at its lower end. Such SHAPE causes only a small amount of the fuel to be injected at the ignition start.

The correct option is (d) Proper injection angle

To explain: A GOOD nozzle should atomize the fuel PROPERLY which is being supplied and it should ALSO maintain the fuel UNIFORMLY and it also needs to maintain proper injection angle and proper direction of the fuel spray.

The CORRECT option is (c) 17-34

The best I can EXPLAIN: The OPENING pressure of the hole-type nozzle varies from 17 to 34MPa. DUE to which the hole type fuel injector has good fuel atomization and this happens in a proper QUANTITY. And the fuel is injected in the cylinder properly.

Correct option is (b) Open type

The best I can explain: The nozzle USED may be CLASSIFIED broadly into the HOLE type and the pintle type wherein the hole type nozzles are generally used in engines with the open type COMBUSTION CHAMBER and the pintle type nozzle has an extension.

The correct option is (c) To lubricate

Easy EXPLANATION: A small quantity of fuel is purposely allowed to LEAK between the nozzle valve and its guide for LUBRICATION purposes. The fuel accumulated AROUND the spindle In this way is drained back to the fuel TANK through the leak-off connection.

The correct choice is (a) Spring

The explanation is: The ACTUAL OPENING fuel- line pressure can be varied by adjusting the INITIAL degree of spring compression. The fuel SPRAY continues till the delivery from the injection pump is exhausted when the spring pressure again suddenly closes the nozzle valve back on its own.

Right option is (d) Dribbling

To explain: The function of a fuel injection PUMP is to DELIVER accurately, the METERED quantity of fuel under high pressure, at the correct instant and in the correct sequence, to the INJECTOR fitted on each engine CYLINDER.

Correct CHOICE is (c) Area

Easiest EXPLANATION: A metering VALVE controlled by the governor REGULATES the amount of fuel entering the ROTOR. Pressing the accelerator pedal increases the area of the metering port allowing more fuel to enter the rotor, thereby increasing the engine speed.

The CORRECT choice is (b) 2

To EXPLAIN I WOULD say: Two CENTRIFUGAL weights connect the input and output SIDES of the timer. When the speed increases, the weights fly apart causing the output segment plates and thereby the camshaft of the fuel injection pump to turn in the direction of rotation.

The correct answer is (a) Helix

To EXPLAIN I would say: The plunged contains a helix at its upper end which serves to control the quantity of FUEL to be injected. As the helix UNCOVERS the spill port, the fuel escapes through the VERTICAL SLOT in the plunger and spill port and pressure are released, shutting the valve down on its seat.

The correct OPTION is (d) Alternator

To elaborate: The pump housing is the main housing that CONTAINS cambox (which SUPPORTS camshaft tappet assemblies, control mechanism, and governor ) and the pumping head which is made of single aluminum alloy WHEREAS the alternator has no ROLE in the pump housing.

Right answer is (b) 8

Explanation: The timing of INJECTION will be required to be advanced with an increase in engine speed. This advancement is done by injection timer which provides a MAXIMUM of 8 DEGREES of Advance. The timer is mounted on the front end of the injection pump and works on the PRINCIPLE of centrifugal FORCE.

Correct option is (d) Rotor

The explanation is: The main parts of a JERK TYPE fuel INJECTION pump are the delivery valve,the plunger, the CONTROL sleeve, and the control rack. Where the delivery valve is spring-loaded. WHEREAS the rotor is absent in this type of injection pump.

Right answer is (c) Control rack

Best explanation: For STARTING the engine from cold, more FUEL is required to be injected which is done by moving the control rack to a position where the excess fuel is delivered by the PUMP. The rack has to be BROUGHT to a normal position immediately after the engine STARTS.