Sprocket

['sprɒkɪt] or ['sprɑkɪt]

解释:

(noun.) thin wheel with teeth that engage with a chain.

(noun.) roller that has teeth on the rims to pull film or paper through.

埃尔维斯手打--From WordNet

解释:

n. a projection on the periphery of a wheel or capstan for engaging the chain.

手打:玛丽安