RRB JE Mechanical-IC ENGINE Questionbank 1

Mechanical-Engineering

In a four-stroke diesel engine, the exhaust valve opens before the piston reaches the Bottom Dead Center to —-? RRB JE (Re-Exam) 04.06.2025

improve fuel atomization
reduce pumping losses
enhance air-fuel mixing
increase the compression ratio

Explanation:

In a four-stroke diesel engine, the exhaust valve opens before the piston reaches BDC to improve fuel atomization. Opening the valve early helps reduce cylinder pressure, leading to better fuel atomization during injection.

In a two-stroke petrol engine, which of the following best describes the sequence of events during an exhaust stroke? RRB JE Stage 2 (22.04.2025 9:00 AM-11:00 AM)

Both ports open simultaneously
The exhaust port opens and closes before the transfer port opens
The transfer port opens first, followed by the exhaust port
The exhaust port opens first, followed by the transfer port

Explanation:

In a two-stroke petrol engine, there are three ports: inlet port, exhaust port, and transfer port. During the exhaust stroke, the exhaust port opens first, followed by the transfer port.

In a two-stroke petrol engine, the primary function of the crankcase is to —-? RRB JE Stage 2 (22.04.2025 2:30-4:30 PM)

cool the engine
act as a primary pumping chamber for the air-fuel mixture
store lubricating oil
house the transfer port

Explanation:

The crankcase acts as a primary pumping chamber for the air-fuel mixture. This is facilitated through piston movement, which draws the mixture into the crankcase and then transfers it to the combustion chamber.

In a four-stroke cycle, the minimum temperature inside the engine cylinder occurs at the —-? RRB JE Stage 2 (22.04.2025 2:30-4:30 PM)

Beginning of exhaust stroke
Beginning of suction stroke
End of exhaust stroke
End of suction stroke

Explanation:

In a four-stroke cycle, the minimum temperature occurs at the beginning of the suction stroke and the maximum temperature occurs at the end of the power stroke.

In a four-stroke engine, the working cycle is completed in —-? RRB JE 29-08-2019

One revolution of the crankshaft
Two revolutions of the crankshaft
Three revolutions of the crankshaft
Four revolutions of the crankshaft

Explanation:

In a four-stroke engine, the working cycle is completed in two revolutions of the crankshaft (720° of crank rotation). In a two-stroke engine, it is completed in one revolution (360°).

For each crankshaft revolution, the camshaft revolves —-? (RRB SSE (Shift-1), 03.09.2015) RRB Kolkata Apprentice Engg., 14.10.2001

one-half turn
two turns
four turns
as many turns as the number of valves in the engine

Explanation:

One turn of the camshaft completes the valve operation for one entire cycle. Since a 4-stroke engine makes two crankshaft revolutions to complete one cycle, the camshaft turns half as fast as the crankshaft.

What is the material of connecting rod? (RRB SSE (Shift-II), 03.09.2015) RRB Bhopal Section Engineer, 24.11.2002

mild steel
forged steel
tool steel
cast iron

Explanation:

Connecting rod is made of forged steel. Piston rings are usually made of cast iron, and the piston is made of aluminium alloy.

Stroke of engine is —-? (RRB SSE (Shift-II), 03.09.2015)

volume of the cylinder
length of the connecting rod
internal dia of cylinder
distance between TDC and BDC

Explanation:

Stroke length is the distance the piston travels in the cylinder, determined by the distance between Top Dead Center (TDC) and Bottom Dead Center (BDC).

A certain engine produces 10 kW indicated power. Its mechanical efficiency is 70%. Then the frictional power is —-? (RRB JE Bhopal Paper II (Shift-II), 26.08.2015)

2 kW
2.5 kW
3 kW
3.5 kW

Explanation:

Mechanical efficiency = BP/IP. 0.7 = BP/10, BP = 7 kW. FP = IP – BP = 10 – 7 = 3 kW.

Morse test is applicable only for —-? (RRB JE Bhopal Paper II (Shift-II), 26.08.2015)

Single cylinder SI engines
Single cylinder CI engines
Multi-cylinder CI engines
Multi-cylinder SI and CI engines

Explanation:

The Morse test is used to determine the power developed in each cylinder in a multi-cylinder IC engine. It is valid only for multi-cylinder engines.

Petrol and diesel engines of automobile are —-? (RRB SSE Secundrabad (Shift-II), 01.09.2015)

Rotary engine
Reciprocating engine
External combustion engine
Carnot heat engine

Explanation:

Petrol and diesel engines used in automobiles are reciprocating type internal combustion engines with piston-cylinder arrangement.

A cyclic device which produces work continuously at the expense of heat input is known as —-? (RRB SSE (Shift-II), 01.09.2015)

Refrigerator
Heat Pump
Heat engine
Throttling

Explanation:

A cyclic device which produces work continuously at the expense of heat input is known as a heat engine. Heat engines are categorized as external combustion and internal combustion engines.

The component of the engine that connects the link between the small end of the connecting rod and the piston is known as —-? (RRB SSE (Shift-II), 01.09.2015)

Cams
fly wheel
Gudgeon pin
Piston ring

Explanation:

Gudgeon pins are made of nickel/chromium alloy steel and connect the piston with the connecting rod.

To connect piston to the connecting rod the ____ are used. (RRB SSE (Shift-II), 02.09.2015) RRB Chandigarh Section Engineer, 26.02.2012

rod caps
cap bolts
small end bearing
gudgeon pins

Explanation:

Gudgeon pins are made of nickel/chromium alloy steel and connect the piston with the connecting rod.

The best firing order for a six cylinder in line engine is —-? (RRB SSE (Shift-III), 02.09.2015)

1-2-3-4-5-6
2-3-4-5-6-1
1-4-2-6-3-5
1-5-3-6-2-4

Explanation:

The best firing order for a six-cylinder in-line engine is 1-5-3-6-2-4. For a four-cylinder in-line engine, it is 1-3-4-2.

Which one of the following item is made of aluminium alloy? (RRB SSE (Shift-III), 02.09.2015) RRB Jammu Section Engg., 2013

piston ring
Connecting rod
piston
crankshaft

Explanation:

The piston is a moving component contained by a cylinder and is made of aluminium alloy. Its purpose is to transfer force from expanding gas to the crankshaft.

For the same rated power and same engine speed of a two stroke engine and a four stroke engine. Which of the following statement is correct? (RRB Mumbai C&G JE 25.10.2009)

Heavier flywheel is required for two stroke engine
Heavier flywheel is required for four stroke engine
Mass of the flywheel should be same for both the engines
Mass of the flywheel depends upon the load on the engine

Explanation:

Two-stroke engines have one power stroke per revolution, providing more uniform torque, so a lighter flywheel can be used. Four-stroke engines have non-uniform torque, requiring a heavier flywheel.

Which of the following factors contribute towards detonation in an engine? (RRB Allahabad JE 25.10.2009)

Engine overheating
High compression ratio
Lean fuel mixture
All option are correct

Explanation:

Factors affecting knocking in SI engines include engine overheating, high compression ratio, lean fuel mixture, high inlet temperature, advanced spark timing, and low engine speed.

The working cycle in case of four stroke engine is completed in ____ number of revolution of crankshaft? (RRB Patna JE 25.10.2009)

Half
1
2
4

Explanation:

The working cycle in a four-stroke engine is completed in 2 revolutions of the crankshaft.

If the temperature of intake air in an IC engine is lowered, its efficiency will —-? (RRB Kolkata Diesel JE 25.10.2009) (RRB JE Ajmer 2014)

increase
decrease
remains unchanged
will increase upto certain limit and then decrease

Explanation:

η = 1 – T₁/T₂. If intake air temperature T₁ decreases, the efficiency increases.

Increasing the compression ratio beyond a certain limit, results to —-? (RRB Bhopal SSE 09.09.2012) (Konkan Railway SSE 2015)

delay in fuel burning
engine knocking
excessive heat in the engine
high fuel consumption

Explanation:

Increasing compression ratio beyond a certain limit results in engine knocking. Factors reducing knocking include high self-ignition temperature, low compression ratio, low inlet temperature and pressure, and long delay period.

The fuel air ratio in a petrol engine fitted with suction carburetor, operating with dirty air filter as compared to clean filter will be —-? (DMRC JE 22.09.2017)

higher
lower
remain unaffected
unpredictable

Explanation:

With a dirty air filter, less air enters, so the fuel-air ratio becomes higher (richer mixture).

Which of the following factors does NOT contribute towards detonation in an engine? (DMRC JE 20.04.2018)

Engine overheating
High compression ratio
Stoichiometric fuel mixture
Wrong spark plug

Explanation:

Stoichiometric fuel mixture does not contribute towards detonation. Factors contributing include engine overheating, high compression ratio, wrong spark plug setting, low engine speed, advanced spark, and high inlet temperature and pressure.

Which of the following sequence is TRUE for same compression ratio and added heat? (RRB Kolkata Diesel JE 25.10.2009)

η_diesel > η_otto
η_diesel < η_otto
η_diesel = η_otto
None of these

Explanation:

For the same compression ratio and heat addition: η_diesel < η_otto. For the same maximum pressure and heat input: η_otto < η_diesel.

Which of the following cannot be classified as an internal combustion engine? (RRB Mumbai C&G JE 25.10.2009)

Diesel engine
Petrol engine
Gas turbine
Steam turbine

Explanation:

Steam turbine is an external combustion engine where heat is produced by burning fuel outside the cylinder. Diesel, petrol, and gas engines are internal combustion engines.

Piston rings usually made of —-? (RRB JE (Shift-I), 27.08.2015)

Carbon steel
Aluminium
Cast-iron
Phosphorous bronze

Explanation:

Piston rings are usually made of cast iron. Two types are compression rings and oil rings, generally made of cast iron alloy with Si and Mn.

The two stroke cycle engine has —-? (RRB Allahabad JE 25.10.2009)

one suction valve and one exhaust valve operated by one cam
one suction valve and one exhaust valve operated by two cams
only ports covered and uncovered by piston to effect charging and exhausting
None of the above

Explanation:

Two-stroke engines have only ports (exhaust, transfer, and inlet) that are covered and uncovered by the piston to effect charging and exhausting.

With increasing temperature of intake air, I.C. engine efficiency —-? (RRB JE Ajmer 2014)

Decreases
Remains same
Increases
Depends on other factor

Explanation:

η = 1 – T₁/T₂. When intake air temperature T₁ increases, the efficiency of the I.C. engine decreases.

For same compression ratio —-? (RRB Patna JE 25.10.2009)

Thermal efficiency of Otto cycle is greater than that of Diesel cycle
Thermal efficiency of Otto cycle is less than that of Diesel cycle
Both (a) & (b)
Thermal efficiency of Otto cycle is equal to that of Diesel cycle

Explanation:

For the same compression ratio, the thermal efficiency of the Otto cycle is greater than that of the Diesel cycle.

One horse power is equal to —-? (RRB Allahabad SSE 09.09.2012)

102 Watts
75 Watts
550 Watts
735 Watts

Explanation:

One horse power (HP) = 735 watts. 1 watt = 1 J/s.

The firing order for a six cylinder engine is —-? (RRB Kolkata SSE 09.09.2012)

1-6-2-5-3-4
1-5-3-6-2-4
1-2-5-4-3-6
1-3-2-6-5-4

Explanation:

For a six-cylinder engine, the most common firing order is 1-5-3-6-2-4.

Fuel injection pressure in solid injection system is approximately in the range of —-? (RRB Jammu SSE 09.09.2012)

10.5 bar
10.5-21 bar
30-50 bar
200-246 bar

Explanation:

Fuel injection pressure in the solid injection system is approximately in the range of 200-246 bar. In air injection, fuel is injected using compressed air.

The crank radius of a single-cylinder I.C. engine is 60 mm and the diameter of the cylinder is 80 mm. The swept volume of the cylinder in cm³ is —-? (RRB Bhubneshwar JE II 29.11.2008)

48
96
301
603

Explanation:

Stroke length L = 2r = 2 × 60 = 120 mm. Vs = π/4 × D² × L = π/4 × (80)² × 120 = 603 × 10³ mm³ = 603 cm³.

Which of the statements is true? (DMRC JE 2013)

All emissions are reduced by selective catalytic converter
Petrol engines take less space than Diesel engine for same power output
Diesel can be filled in petrol engine, but not vice versa
Knocking doesn’t depend on spark timing

Explanation:

Petrol engines take less space than diesel engines for the same power output. SI engines have less space, lighter flywheel, lower vibration, higher speed, and higher power/weight ratio.

The difference between indicated power and Frictional power is indicated as —-? (Konkan Railway STA 2017)

Resultant power
Brake power
None of the above
Rated power

Explanation:

Indicated power = Brake power + Frictional power. Therefore, Brake power = Indicated power – Frictional power.

Crankcase ventilation helps in —-? (RRB Kolkata Diesel JE 25.10.2009)

increasing the breathing capacity of the engine
remove harmful particles from the engine
none of the above
provide lubrication to the engine

Explanation:

Crankcase ventilation removes unwanted gases (blow-by gases) from the crankcase. Two-stroke engines with crankcase compression do not need crankcase ventilation.

Which of the following statement is not true about valve? (RRB Allahabad JE 25.10.2009)

Exhaust valve is made of two different materials
Exhaust valve diameter is bigger than inlet valve diameter
Inlet valve diameter is bigger than exhaust valve diameter
Valve used in 4-stroke diesel engine are called poppet valves

Explanation:

Inlet valve diameter is bigger than exhaust valve diameter. Exhaust valves are made of two different materials, and valves used in 4-stroke diesel engines are poppet valves.

How many cylinders does a rotary internal combustion engine has? (RRB Bhopal SSE 09.09.2012)

Explanation:

A rotary internal combustion engine consists of seven cylinders in one plane, all revolving about a fixed centre.

Which of the following statements is incorrect regarding a four stroke engine as compared to a two stroke engine? (RRB Allahabad JE 09.09.2012)

It requires a heavier foundation
It can be easily started
More cooling time is available
It occupies greater space

Explanation:

In a four-stroke engine, starting is not as easy as compared to a two-stroke engine. It occupies greater space and requires a heavier foundation.

____ is the duration of the crank angle after exhaust stroke in which both inlet valve and exhaust valve are open. (RRB Allahabad JE 19.12.2010)

Negative overlap angle
Positive overlap angle
Flank angle
None of the above

Explanation:

Positive overlap angle is the duration of the crank angle after the exhaust stroke in which both inlet valve and exhaust valve are open.

Which is the wrong assumption for calculation of air standard efficiency? (RRB Bhubneshwar JE II 29.11.2008) RRB Bangalore Section Eng. (Mech.), 01.02.2009

All processes are reversible
Specific heat remains constant at all temperatures
No account of the mechanism of heat transfer is considered
Gases dissociate at higher temperatures

Explanation:

Air standard efficiency assumes air is the working fluid, air behaves as an ideal fluid, all processes are reversible, specific heat remains constant, and no account of heat transfer mechanism is considered. Gases dissociate at higher temperatures is not an assumption.

In an IC engine, the connecting rod connects which of the following pair of parts? (RRB Kolkata SSE 09.09.2012) RRB Kolkata Technical-Engg., 20.08.2006

Piston and crankshaft
Cylinder and crankshaft
Cylinder and piston
None of these

Explanation:

The connecting rod connects the piston and the crankshaft in an IC engine.

The instrument used to check the state of charge of battery is —-? (RRB Allahabad JE 19.12.2010)

Hydrometer
Hygrometer
Battery eliminator
Anemometer

Explanation:

A hydrometer is used to check the state of charge of a battery. It measures the specific gravity of the electrolyte.

Engine pistons are usually made up of aluminium alloys because —-? (BMRCL JE 24 Feb.2019)

It is lighter
It is stronger
It has less wear
It absorbs shocks

Explanation:

Engine pistons are usually made of aluminium alloys because they are lighter in weight.

The materials used for cylinder block are —-? (DMRC JE 22.09.2017)

Cast iron and steel
Cast iron and aluminium
Steel and aluminium
Brass and steel

Explanation:

Cylinder and cylinder head are made of cast iron and aluminium. Pistons are made of aluminium alloy, connecting rods of forged steel, and crankshafts of alloy steel.

The minimum number of compression rings in an automotive engine is —-? (RRB Bhubneshwar JE-II 19.12.2010)

one
two
three
four

Explanation:

A minimum of two compression rings are required because of the high pressure difference between the combustion chamber and the crankcase at the beginning of the power stroke.

The function of a crosshead is to guide motion of the ____ and to prevent it from bending. (RRB Mumbai SSE 05.10.2008)

piston rod
connecting rod
eccentric rod
valve rod

Explanation:

The function of a crosshead is to guide the motion of the piston rod and to prevent it from bending. It enables the connecting rod to freely move outside the cylinder.

The Fan belt in automobiles is —-? (DMRC JE 2013)

B-section V belt
A five layer flat belt
E-section V belt
A three layer flat belt

Explanation:

The fan belt in automobiles is a B-section V belt. It is a flexible synthetic rubber band that connects various engine components.

What material is used for the insulating body of a spark plug? (Konkan Railway TA 2017)

Silica
Alumina
Glass
Dolomite

Explanation:

Alumina is used for the insulating body of a spark plug. A spark plug has a metal threaded shell electrically isolated from a central electrode.

Which of the following fuel has maximum resistance to detonation? (RRB Gorakhpur RDSO SSE 25.10.2009)

Toluene
iso-octane
Benzene
n-heptane

Explanation:

Iso-octane is a very good anti-knock fuel and is assigned a rating of 100 octane number.

Dynamo is used to convert —-? (RRB Mumbai C&G SSE 25.10.2009)

mechanical energy into electrical energy
electrical energy into mechanical energy
mechanical energy into chemical energy
chemical into electrical energy

Explanation:

A dynamo is used to convert mechanical energy into electrical energy. It creates direct current using a commutator.

In two-stroke engine, the cycle completes in —-? (RRB Kolkata SSE 09.09.2012)

two revolution of crank shaft
one revolution of crank shaft
half revolution of crank shaft
four revolution of crank shaft

Explanation:

In a two-stroke engine, one power stroke is obtained in each revolution of the crankshaft. In a four-stroke engine, one power stroke is obtained in two revolutions.

In magneto ignition system, as the engine speed increases, the value of current —-? (RRB Allahabad JE 25.10.2009)

increases
decreases
remains the same
may increase or decrease

Explanation:

In a magneto ignition system, as engine speed increases, the value of current increases. Magneto is best at high speeds and is used for sports cars and aircraft engines.

Two stroke engines have —-? (RRB Chandigarh SSE 25.10.2009)

valves
ports
both (a) & (b)
None of these

Explanation:

Two-stroke engines have ports – exhaust ports, transfer ports, and inlet ports.

The engine part that joins piston and connecting rod is called —-? (Konkan Railway TA 2017)

piston crown
piston ring
crank pin
gudgeon pin

Explanation:

The gudgeon pin connects the piston with the connecting rod. It is made of nickel/chromium alloy steel.

A square engine has —-? (DMRC JE 20.04.2018)

Square cylinder
Square piston
Cylinder bore equal to stroke length
None of these

Explanation:

A square engine has cylinder bore (D) equal to stroke length (L). D > L is over square, and D < L is under square.

Detonation is said to take place in the engine when —-? (RRB Mumbai JE 19.12.2010)

sudden acceleration is imparted to the engine
temperature rise to too high
high pressure waves are setup
combustion of fuel takes place without spark provided to it

Explanation:

Detonation occurs when excessive heat and pressure cause the air/fuel mixture to ignite on its own. Detonation is the cause and knocking is the after-effect.

For a four-cylinder engine, the firing order for evenness of torque is —-? (RRB Allahabad SSE 19.12.2010)

1 3 2 4
1 2 3 4
1-4-2-3
1-3-4-2

Explanation:

The possible firing orders for a four-cylinder engine are 1-3-4-2 and 1-2-4-3. The former is in common use.

The silencer of an IC engine —-? (BMRCL JE 24 Feb. 2019)

reduces noise
decreases brake specific fuel consumption
increases brake specific fuel consumption
has no effect on efficiency

Explanation:

The silencer is provided to reduce the noise of the IC engine. Back pressure reduces engine efficiency and power.

Number of working strokes per minute for a two stroke cycle engine as compared to speed of the engine in rpm, is —-? (DMRC JE 22.09.2017)

half
double
same
four times

Explanation:

For a two-stroke engine, the number of working strokes per minute is the same as the engine speed in rpm. For a four-stroke engine, it is half the rpm.

If in a diesel engine petrol is used then the engine will —-? (JMRC JE 10.06.2017)

run at high speed
run with high knocking
run at low speed
explode

Explanation:

If petrol is used in a diesel engine, it will run with high knocking because diesel fuel is less volatile. Combustion starts before TDC, leading to knocking.

Which is not a part of magneto-ignition system? (RRB Bhubneshwar JE-11 19.12.2010)

induction coil
circuit breaker
condenser
battery

Explanation:

Battery is not a part of the magneto-ignition system. Magneto systems include induction coil, circuit breaker, condenser, magnet, and distributor.

The purpose of the flywheel in an IC engine is —-? (RRB Chandigarh SSE 25.10.2009)

To increase the power capacity of the engine
To reduce the vibration in an engine
To regulate the fuel supply
To keep the output power constant at the crankshaft

Explanation:

The flywheel stores power from the power stroke and supplies it back during suction, compression, and exhaust strokes to keep output power constant at the crankshaft.

For the same compression ratio and heat input, the efficiency of an Otto cycle engine as compared to diesel engine is —-? (RRB Patna JE 25.10.2009)

More
Less
Equal
None of these

Explanation:

For the same compression ratio and heat input, Otto cycle efficiency > Dual cycle efficiency > Diesel cycle efficiency.

In a four stroke engine, for how much angular displacement of crank shaft, the exhaust valve actually remains open? (RRB Kolkata SSE 09.09.2012)

180°
More than 180°
Less than 180°
360°

Explanation:

In a four-stroke engine, the exhaust valve actually remains open for more than 180° of crankshaft displacement (EVO to EVC).

Violent sound pulsations within the cylinder of an IC engine are caused due to —-? (RRB Jammu SSE 09.09.2012)

heavy turbulence and vibration
improved scavenging
heavy supercharging
detonation

Explanation:

Violent sound pulsations within the cylinder of an IC engine are caused due to detonation.

In an IC engine, the function of the governor is to control which of the following? (RRB Mumbai JE 05.10.2008)

Maximum speed
Mean speed
Engine temperature
Load fluctuations

Explanation:

The function of the governor is to maintain the engine speed whenever there is a variation of load.

The correct sequence of stroke in a four stroke engine is —-? (RRB Mumbai SSE 19.12.2010)

Suction, compression, exhaust and expansion
expansion, compression, suction and exhaust
suction, compression, expansion and exhaust
suction, expansion, compression and exhaust

Explanation:

The correct sequence of strokes in a four-stroke engine is suction, compression, expansion (power), and exhaust.

For the same output, same speed and same compression ratio the thermal efficiency of a two stroke cycle petrol engine as compared to that for four stroke cycle petrol engine is —-? (RRB Chandigarh SSE 25.10.2009)

less
same as long as output is same
same as long as compression ratio is same
more

Explanation:

Two-stroke petrol engines have lower thermal efficiency compared to four-stroke petrol engines for the same output, speed, and compression ratio.

The power from the engine to the rear axle of an automobile is transmitted by means of —-? (RRB Jammu JE 25.10.2009)

Worm & worm wheel
Bevel gears
Spur gears
Hooke’s joint

Explanation:

A Hooke’s joint (universal joint) is used to transmit power from the gearbox of the engine to the differential in an automobile.

The level of oil in engine cylinder should be checked —-? (RRB Allahabad SSE 09.09.2012)

Before starting
During idling
During cranking
While running

Explanation:

The oil level in the engine should be checked before starting for accurate measurement.

If in a petrol engine by mistake diesel fuel is supplied then engine will be —-? (RRB Gorakhpur Design SSE 09.09.2012)

Not run
Give dense smoke and will consume more fuel
Run for some time and then stop
Run smoothly

Explanation:

If diesel fuel is supplied to a petrol engine, the engine will not run because diesel has a low auto-ignition point and will start burning during partial compression before TDC.

Stoichiometric air-fuel ratio by volume for combustion of methane in air is —-? (RRB Chandigarh SSE 09.09.2012)

15:1
17.16:1
9.53:1
10.58:1

Explanation:

For CH₄ + 2O₂ + N₂ → CO₂ + 2H₂O + N₂, the stoichiometric air-fuel ratio is approximately 9.53:1.

The automobile exhaust will have maximum of hydrocarbons when the vehicle is —-? (RRB Mumbai JE 19.12.2010)

Idling
Cruising
Accelerating
Running at high speeds

Explanation:

The automobile exhaust will have maximum hydrocarbons when the vehicle is idling.

Which is the antifreeze solution commonly used in automobiles? (RRB Allahabad SSE 19.12.2010)

Carbon disulphide
Alcohol
Ammonia chloride
Brine

Explanation:

Commonly used antifreeze solutions are alcohol (ethylene glycol) and water. Ethylene glycol is used in automobile and industrial applications.

In a 4-stroke IC engine, the turning moment during the compression stroke is —-? (BMRCL JE 24 Feb. 2019)

Positive throughout
Negative throughout
Positive during major portion of the stroke
Negative during major portion of the stroke

Explanation:

In a 4-stroke IC engine, the turning moment during the compression stroke is negative throughout.

The temperature of interior surface of cylinder wall of I.C. Engine is normally not allowed to exceed —-? (DMRC JE 22.09.2017)

80°C
130°C
180°C
340°C

Explanation:

The peak cylinder gas temperature is approximately 2800 K, while the cylinder inner wall surface temperature may be about 180°C due to cooling.

In which of the following type of engine, the inlet and exhausted valves are fitted in the cylinder head? (Konkan Railway STA 2017)

L-head engine
I-head engine
T-head engine
F-head engine

Explanation:

In an I-head engine, the inlet and exhaust valves are fitted in the cylinder head. In L-head, both valves are on one side. In T-head, inlet valves are on one side and exhaust on the other.

Which one of the following is not a function of piston rings? (RRB Kolkata Diesel JE 25.10.2009)

To work as sliding seal between piston and cylinder
To control the lubrication between the piston and cylinder walls
To assist the cooling of piston
To assist the cooling of cylinder liner

Explanation:

Functions of piston rings include working as a sliding seal, controlling lubrication, and assisting in cooling the piston. They do not assist in cooling the cylinder liner.

1200 cc 4-Cylinder engine has —-? (RRB Chandigarh SSE 09.09.2012)

Swept volume of each cylinder = 300 cc
Total volume of each cylinder = 300 cc
Total volume of each cylinder = 1200 cc
Swept volume of each cylinder = 1200 cc

Explanation:

A 1200 cc 4-cylinder engine has swept volume of each cylinder = 1200/4 = 300 cc.

Number of positive plates in a cell of Lead-Acid battery is —-? (RRB Allahabad JE 09.09.2012)

One more than the number of negative plates
One less than the number of negative plates
Two more than the number of negative plates
Two less than the number of negative plates

Explanation:

Number of positive plates = Number of negative plates – 1. Positive plates are dark brown and negative plates are grey when fully charged.

The battery test which is similar to the situation produced by the starting motor is —-? (RRB Bangalore SSE 09.09.2012)

Specific gravity test
Open voltage test
High discharge test
Cadmium test

Explanation:

The high discharge test is similar to the situation produced by the starting motor.

The electrolyte used in Lead-Acid battery is —-? (RRB Mumbai C&G SSE 25.10.2009)

Sulphuric acid and lead
Distilled water and lead
Sulphuric acid and distilled water
Only distilled water

Explanation:

The electrolyte used in a lead-acid battery is sulphuric acid and distilled water. The cathode is made of lead dioxide and the anode is metallic lead.

Which of the following is NOT a requirement of an ignition system in a spark-ignition engine? RRB JE (Re-Exam) 04.06.2025

Maintaining consistent spark duration across all RPMs
Generating sufficient voltage to jump the spark plug gap
Mixing air and fuel in the intake manifold
Timing the spark to coincide with the compression stroke

Explanation:

Mixing air and fuel in the intake manifold is not a requirement of an ignition system. Requirements include maintaining consistent spark duration, generating sufficient voltage, and timing the spark with the compression stroke.

Which of the following best describes the primary function of a simple carburetor in a petrol engine? RRB JE (Re-Exam) 04.06.2025

To electronically control the fuel injection timing
To compress the air-fuel mixture before combustion
To atomise and mix fuel with air in the proper ratio
To regulate exhaust emissions via catalytic conversion

Explanation:

The primary function of a carburetor is to atomise and mix fuel with air in the proper ratio. CI engines do not require a carburetor as only air is compressed and fuel is injected directly.

What is the effect of compression ratio (CR) on the air standard efficiency of Otto and Diesel cycles? RRB JE (Re-Exam) 04.06.2025

CR has no effect on efficiency
Efficiency increases with CR in SI engines and decreases in CI engines
Higher CR always leads to higher efficiency
Lower CR always leads to higher efficiency

Explanation:

Higher compression ratio always leads to higher efficiency. Otto cycle CR is 6-12 and Diesel cycle CR is 16-20. Otto cycle efficiency is higher than Diesel at the same CR.

In a two-stroke petrol engine, the inlet port is opened by the piston —-? RRB JE (Re-Exam) 04.06.2025

30° to 40° before BDC
40° to 55° before BDC
30° to 40° after BDC
45° to 55° before TDC

Explanation:

In a two-stroke petrol engine, the inlet port is opened by the piston 30° to 40° before BDC.

The thermal efficiency of the Otto cycle is a function of —-? RRB JE (Re-Exam) 04.06.2025

engine size and speed
heat supplied and pressure ratio
temperature and mass flow rate
compression ratio and the ratio of specific heats

Explanation:

The thermal efficiency of the Otto cycle is a function of compression ratio and the ratio of specific heats. It consists of two reversible isentropic and two isochoric (constant volume) processes.

In a compression-ignition engine, the ignition of fuel occurs due to —-? (RRB Allahabad JE 19.12.2010)

Spark plug
Fuel injector
Combustion chamber
Heat from compressed air

Explanation:

In a diesel engine, only air is compressed and fuel is injected at the end of compression. Fuel is ignited by the high temperature of compressed air. Compression ratio for diesel is 16-24 and for petrol is 6-12.

What happens to the rating of a diesel engine, when the temperature of intake air is increased? (JMRC JE 10.06.2017)

Increases linearly
Decreases linearly
Increases parabolically
Decreases parabolically

Explanation:

With an increase in inlet temperature, efficiency decreases linearly, and so the rating decreases linearly.

Which of the following medium is compressed in a diesel engine? (DMRC JE 22.09.2017)

Air
Fuel
Air and fuel
Air and lubricant oil

Explanation:

Air is compressed in a diesel engine. Only air is induced during suction and compressed during the compression stroke. Fuel is injected just before the desired start of combustion.

In the opposed piston diesel engine, the combustion chamber is located —-? (JMRC JE 10.06.2017)

above the piston
below the piston
between the pistons
anywhere

Explanation:

In opposed-piston engines, pistons reciprocate opposite to each other in one cylinder. The combustion chamber is formed between the pistons near top dead centre.

Which denoted path is followed by the Diesel Cycle in the P-V diagram? (RRB Allahabad SSE 19.12.2010)

1-2-4-7-1
1-2-3-5-7-1
1-2-6-7-1
None of these

Explanation:

Diesel cycle path: 1-2-6-7-1. Otto cycle: 1-2-4-7-1. Dual cycle: 1-2-3-5-7-1.

What is the other name for diesel cycle? (DMRC JE 2013)

Constant pressure cycle
Constant temperature cycle
Constant volume cycle
None of these

Explanation:

The diesel cycle is also known as the constant pressure cycle because heat is added at constant pressure.

How is the rate of burning of fuel controlled in the compression ignition engine? (RRB Mumbai JE 19.12.2010)

Controlling the design of cylinder
Rate of injection of fuel
Rate of air into carburetor
Controlling temperature of the engine

Explanation:

The rate of burning of fuel in a compression ignition engine is controlled by the rate of injection of fuel.

Which of the following is a false statement? Excess quantities of Sulphur in diesel fuel are objectionable because it may cause the following? (RRB Chandigarh SSE 25.10.2009)

piston ring and cylinder wear
formation of hard coating on piston skirts
oil sludge in the engine crank case
detonation

Explanation:

Excess sulphur in diesel fuel causes piston ring and cylinder wear, formation of hard coating on piston skirts, and oil sludge. It does not cause detonation.

Installation of supercharger on a four-cycle diesel engine can result in the following percentage increase in power —-? (RRB Jammu JE 25.10.2009)

upto 25%
upto 35%
upto 50%
none of these

Explanation:

Installation of a supercharger on a four-stroke diesel engine increases power up to 70-80%.

In order to prevent formation of carbon on the injector, the temperature (in °C) of nozzle tip should be —-? (RRB Patna JE 25.10.2009)

less than 100
between 100-250
between 250-300
between 400-500

Explanation:

To prevent carbon formation on the injector, the nozzle tip temperature should be between 250-300°C.

A petrol engine has compression ratio from —-? DMRC JE 17.04.2018 12:15-2:30 PM (NMRC 05.03.2017, 12 p.m.) (RRB Jammu SSE 09.09.2012)

6 to 10
10 to 15
25 to 40
15 to 25

Explanation:

A petrol engine has a compression ratio from 6-12. Compression ratio = (Swept volume + Clearance volume)/Clearance volume.

The functional requirement of spark plug is to allow a spark to form —-? (RRB Allahabad SSE 09.09.2012)

in the inlet port to initiate combustion process
none of the above
within combustion chamber to initiate burning
combustion if self-ignition does not happen

Explanation:

The function of the spark plug is to produce a spark of adequate intensity within the combustion chamber to initiate combustion and propagate the flame front effectively.

For a given compression ratio, to reduce the tendency to knock in an SI engine —-? (RRB Jammu JE 25.10.2009)

Spark timing may be retarded
The spark plug may be located farthest from the exhaust valve
A quiescent combustion chamber with slower flame propagation rate may be used
Organic nitrites may be used in the fuel

Explanation:

To reduce knocking in an SI engine, spark timing may be retarded. Factors reducing knocking include high self-ignition temperature, low compression ratio, low inlet temperature/pressure, and high octane rating.

In carburetors, the top of the fuel jet with reference to the level in the float chamber is kept —-? (DMRC JE 2013)

at slightly higher level
at slightly lower level
anywhere
at the same level

Explanation:

In carburetors, the top of the fuel jet with reference to the float chamber level is kept at a slightly higher level. The nozzle tip is kept 4-5 mm above the petrol level (tip height).