Definition

Noun: A tappet is a short lever or projection in machinery, especially in an internal combustion engine. It is moved by contact with a cam or other part and transmits this motion to another component, such as a valve, to open and close it.

Usage

The word tappet is a technical term used primarily in mechanical and automotive engineering. It refers to a specific component within an engine's valve train mechanism.

Examples

• The mechanic adjusted the tappet clearance to reduce the engine noise.
• A worn tappet can cause improper valve timing and reduce engine performance.
• The design includes hydraulic tappets that require no manual adjustment.

Advanced Usage

• Tappet clearance (also called valve lash): The small gap between the tappet and the valve stem, which is crucial for proper engine operation.
• Tappet noise: A rhythmic tapping sound from an engine, often indicating that the tappet clearance needs adjustment.

Variants and Related Words

• Valve tappet: A more specific term emphasizing its function in operating a valve.
• Hydraulic tappet: A type of tappet that uses engine oil pressure to automatically maintain zero clearance, eliminating the need for manual adjustment.

Synonyms

• Cam follower: A general term for any component that follows the profile of a cam.
• Valve lifter: A common synonym in automotive contexts, especially in North American English.

Related Terms (Not Synonyms)

• Cam: The rotating egg-shaped lobe that presses against the tappet to create its motion.
• Pushrod: In some engine designs, the rod that sits between the tappet and the rocker arm to transmit motion.
• Rocker arm: A lever that pivots to push the valve open, often activated by a pushrod from the tappet.

Noun

1. a lever that is moved in order to tap something else