Which of the following engine component responsible of valve operation?

Explanation:

Camshaft:

• The camshaft is used to convert the rotary motion into a reciprocating motion with the help of the cam lobe.
• It is responsible for valve operation.
• This reciprocating motion is transmitted to the valve through the tappet, push-rod, and rocker levers.
• The camshaft is driven by a crankshaft and it rotates at half the speed crankshaft.
• The camshaft also drives the oil pump shaft.
• In petrol engines, the fuel pump and the distributor get their drive from the camshaft.

Valve operating mechanisms:

• Two types of valve operating mechanisms are used in engines. They are as follows:
  • Slide valve mechanism
  • Overhead valve mechanism
• When the camshaft rotates, the cam lobe (1) lifts the tappet (2) upward.
• When the tappet (2) moves up, it pushes the push-rod (3) and one end of the rocker's arm upwards.
• The other end of the rocker arm’s (4) tip, moves downward and the valve (5) opens against the spring’s (6) tension.
• When the cam lobe (1) reaches the maximum height, the valve opens fully.
• Further rotation of the camshaft causes the tappet (2) to move down and the valve is closed by the tension of the spring (6).
• Tappet clearance is provided in between the valve (5) tip and the rocket arm’s (4) tip.
• This clearance can be adjusted by the adjusting screw (7) and the lock nut (8).
• In many cases, even these rockers or followers and their pivots are dispensed with and the valves are actuated directly by the camshaft through bucket type.