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The correct option is (b) False

Easy EXPLANATION: When cam pushes the tappet there is an OPPOSITE force from pushrod, pushrods are in direct contact with rocker ARM and the tappet.So pushrods are not in direct contact with the valve.

Correct OPTION is (b) Circular

The best I can EXPLAIN: PUSHRODS are a hollow TUBE made by DURALUMIN metal with a circular cross-section which results in a reduction of weight and high strength.

The CORRECT answer is (b) False

Explanation: PUSHRODS are made with a hollow rod. The MAIN factor here is the weight, for the same work hollow rod is more efficient than a solid rod, and both the rods have the same STRENGTH.

The correct option is (d) Force fit

The EXPLANATION is: The sockets at the END of pushrod are CONNECTED by force fit and Ball and sockets are the TWO types of joints used at the end of the pushrod.

The correct CHOICE is (a) Ball and sockets

Best explanation: Ball and socket is the mechanism INVOLVED in pushrod. The socket is made at ONE end of the pushrod and ball is present in that. Above the ball, a tappet is present to REDUCE the FRICTION.

Right option is (c) Cam and ROCKER

To elaborate: Pushrods are connected between cam and rocker of the engine component. These are hollow tubesmade by duralumin MATERIAL. This results in good STRENGTH and low WEIGHT.

Right choice is (a) Overhead valve

For explanation: Pushrods are used inoverhead valve type of valve mechanized engine and are connected between CAM and rocker of the engine component. This USES a ball and socket MECHANISM.

The CORRECT option is (b) 9.37mm

To explain I would say: Pitch of COILS=\(\frac{FREE \, LENGTH}{(Nt-1)}\)

=\(\frac{131.11}{(15-1)}\)

= 9.37mm

Correct ANSWER is (B) 20mm

The best I can explain: WIDTH of flange=2.5t

= 2.5(8)

=20mm

Right CHOICE is (d) 131.11mm

For EXPLANATION I would say: Free LENGTH= SOLID length+δmax+0.15δmax

=90+35.75+0.15(35.75)

= 131.11mm

The CORRECT choice is (B) 48MM

The BEST I can explain: D=Cd

= 8×6

= 48mm

The correct ANSWER is (c) Negative pressure

For explanation: The PURPOSE of the VALVE SPRING is to EXERT force on the rocker arm and When valves are closed negative pressure is built inside the engine cylinder.

Correct choice is (a) Rocker arm

For explanation: PISTON and Cylinder liner are held very CLOSE together such that the clearance between them can be neglected and the purpose of the VALVE spring is to EXERT force on the rocker arm.

The CORRECT CHOICE is (B) 30mm

The BEST I can EXPLAIN: D3=2d

=2×15

=30mm

The CORRECT answer is (b) Z=\(\frac{l_2}{4}\)

For explanation: Z=\(\frac{l_2}{4}\)is the FORMULA to calculate uniformly distributed LOAD between the pin and the roller and t=\(\frac{l}{2}\) is the formula to calculate the thickness of each EYE.

The CORRECT option is (b) x=\(\frac{l_2}{6}\)

For explanation I would say: x=\(\frac{l_2}{6}\) is the formula to CALCULATE the triangular DISTRIBUTION of the load between the pin and the EYE andD2=2d2 is the formula to calculate the OUTER diameter of the eye.

Correct option is (c) D2=2d2

The explanation: t=\(\FRAC{L}{2}\) is the formula to calculate the thickness of each eye and D2=2d2 is the formula to calculate the OUTER diameter of the eye. Hence, D2=2d2 is the right ANSWER.

The correct option is (a) Centre of the pivot

To explain I would say: In the cross-section of the ROCKER ARM, the bending moment is maximum at the Centre of the pivot POINT. Hence, the EYE passing through this point is strengthened.

The correct ANSWER is (d) t=\(\frac{l}{2}\)

To explain: t=\(\frac{l}{2}\) is the formula to calculate the THICKNESS of each eye and D2=2d2is the formula to calculate the OUTER DIAMETER of the eye. Hence, t=\(\frac{l}{2}\) is the right answer.

Right OPTION is (c) Bending moment

To explain I would SAY: The maximum FORCE exerted by the valve will DETERMINE the bending moment on the rocker-arm. Hence, the bending moment is the right answer.

Right CHOICE is (b) Inlet

The BEST I can explain: In a four-stroke engine, the EXHAUST valve is heavily loaded when compared to the inlet valve and the force on the inlet valve is LESS comparing to the exhaust valve.

The correct option is (a) Exhaust

Explanation: In a four-stroke engine, the exhaust valve is HEAVILY LOADED when compared to the INLET valve due to SMALLER in size and experience a lot of heat.

Right option is (c) I-section

The best explanation: To reduce the WEIGHT and INERTIA force of the rocker arm I-section cross-section is used. WHENEVER the inertia force is important, then I-section will be the FIRST option.

The CORRECT CHOICE is (d) Open or close the INLET or exhaust valve

To elaborate: The basic FUNCTION of the rocker arm, concerning the motion of the CAM and follower, is to open or close the inlet or exhaust valve. This experience lot of heat.

Right answer is (b) Silicon-Chromium STEEL

Explanation: INLET valves are made of Nickel-Chromium steel and exhaust valves are made of Silicon-Chromium steel. In heavy-duty ENGINES, the valves are made by chromium-vanadium steel.

The correct CHOICE is (B) Nickel-Chromium steel

To explain I WOULD say: Inlet valves are made of Nickel-Chromium steel and EXHAUST valves are made of Silicon-Chromium steel. In heavy-duty ENGINES, the valves are made by chromium-vanadium steel.

The correct CHOICE is (c) Chromium-vanadium steel

Best explanation: In heavy-duty ENGINES, the VALVES are made by chromium-vanadium steel and in normal CARS, nickel-Chromium steelor silicon-Chromium steel are used.

The correct choice is (d) Margin

The explanation: The small SPACE between the head and the face is KNOWN as margin and the poppet valve head at the end of a rod is known as the STEM. The margin contributes to improve airflow and DURABILITY.

The correct answer is (a) Self-centering

Best explanation: The small conical surface of the valve results in Self-centering. This is ONE of the important PROPERTIES if this NEGLECTED, the CHARGE won’t be compressed properly.

Correct option is (c) 30° to 45°

Best explanation: 30° to 45° is the face angle RANGE for a poppet valve. The face angle and the face can be ALTERED accordingly using GRINDING or SKIMMING MACHINES.

The CORRECT answer is (b) Face

Best explanation: The poppet valve that consists of a DISK known as the head, the poppet valve head at the END of a ROD is known as stem and the valve is a conical surface that comes in CONTACT with a valve seat known as a face.

The correct answer is (a) Stem

The EXPLANATION is: The POPPET valve that consists of a DISK known as head and the poppet valve head at the end of a rod is known as the stem. This experience lesser heat COMPARED to the face of the valve.

Right CHOICE is (c) Head

For EXPLANATION: The poppet valve that consists of a disk KNOWN as head and the poppet valve head at the end of a rod is known as the stem. Stem experience lesser heat compared to the FACE of the valve.

The correct ANSWER is (d) Mushroom and SLEEVE valves

Easiest explanation: Mushroom and sleeve valves are the two types of valves used in the INTERNAL combustion ENGINES and the mushroom valves are ALSO known as poppet valves.

Right option is (b) Compress

The best explanation: The spring GETS compressed when valves are OPENED which means the CAMS are in action and push the push ROD thereby rocker-arm. DEPENDING on usage, the spring loses its strength.

The correct choice is (b) Cam

For explanation I would say: ONE end of the spring is secured to the valve stem and the other end RESTS on the cylinder and the FOLLOWER rests CAMS of the valve-gear mechanism.

Right answer is (B) Cylinder

Best explanation: One end of the SPRING is secured to the valve STEM and the other end rests on the cylinder. The cylinder is fixed support and WITHSTANDS the high-pressure.

The correct CHOICE is (c) Oscillatory motion

For explanation: The opening of valves is due to the oscillatory motion of the ROCKER arm. This is due to the force by INITIAL COMPRESSION presses the valve down on its seat.

Right ANSWER is (d) DOWNWARD

Easiest explanation: When the right end of the rocker arm is pushed up, the left end moves in a downward direction and pushes the spring-loaded valve to ACHIEVE the motion.

Right answer is (a) Fulcrum

The explanation is: As the CAM ROTATES,the cam pushes the follower, and pushrod is moved in an upward direction and the rocker arm is PIVOTED at its CENTERUSING a Fulcrum PIN.

The correct answer is (c) Upward

For explanation I WOULD SAY: As the cam rotates,the cam pushes the follower, and push ROD is moved in an upward direction and the ROCKER arm is pivoted at its centerutilizing FULCRUM pin.

The correct answer is (B) Belt-drive

The best I can explain: The camshaft is ROTATED by Belt-drive mechanism in cars and this belt is also called a timing belt. In BIKES, we have a timing CHAIN supported by a torsion supporting bar.