Mechanics

Camshaft Lifter Tappet Follower

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This article we will explain camshaft, lifter, tappet and follower configurations present in the automotive industry.

Overhead Camshaft Configuration

Step 1 - A lifter is located either in the engine block or cylinder head, and is controlled by oil pressure supplied by the oil pump. This overhead camshaft configuration uses a lifter and a roller follower to push against the valve spring to open the valve, either intake or exhaust.


Overhead Camshaft Lifter Follower (Cutaway Cylinder Head)

Step 2 - The lifter provides the automatic adjustment (In older engines, valve lash must be adjusted by hand) which is supplied by oil pressure. When the lifter is forced away from the camshaft by rotation, the oil valve inside the lifter is closed which traps the oil inside the lifter while opening the valve. The follower then transmits the force to the valve stem.


Camshaft Follower

Step 3 - Although this follower is designed with a roller, some simply ride against the camshaft without a roller.

Step 4 - As in all hydraulic lifter configurations, engine oil pressure is used to lubricate and pressurize the lifter plunger.


Lifter Oil Passage (Cutaway)

Camshaft In Block

Step 5 - The alternative design to overhead valve train construction is the in block camshaft, (IBC) this design is traditionally an older design and less efficient than its counterpart due to the added weight of the additional components such as a pushrod and full rocker arm which required a heavier valve spring.


Camshaft In Block (Bottom)

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AUTHOR


Written by
Co-Founder and CEO of 2CarPros.com
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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Article first published (Updated 2014-07-30)