Valve Train

Question 1

What do the the valves do?

Answer 1

• open and close at precise intervals by either the rockers or camshaft directly
• to allow either intake air in or exhaust gases out of the engine

Question 2

What does the push rods and lifters do?

Answer 2

• run on the camshaft and transfer rotational movement into linear movement
• to actuate the rockers, some lifers have rollers to reduce friction

Question 3

What’s does the valve spring do?

Answer 3

• forcibly and positively close the valves to seal the combustion chamber

Question 4

What does the rockers do?

Answer 4

• transfer upwards motion of of the pushrods into downwards motion to open the valves
• also changes the ratio to provide enough valve lift

Question 5

What does the cam shaft do?

Answer 5

• used to precisely to open and close the valve injectors
• can operate direct on the valves in the case of overhead cam(s) or via pushrods, lifters and rockers for conventional engines