They might even remember that George worked for Spacely Sprockets.

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Each print must be delivered in its metal canister by courier to the cinema, where the reels are spliced together, spooled on a platter and fed through the sprockets of a film projector.

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Derailleur gears have a front mech (short for front gear mechanism) to shift the chain between two or three chainrings and a rear mech (short for rear gear mechanism) with up to 10 sprockets.

BBC: Sport

For a century, despite the additions of surround-sound audio systems and widescreen formats, the technology was more or less -- pardon the term -- static: a strip of celluloid, a series of sprockets and light.

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Pay particular attention to the jockey wheels (these are small wheels in the chain cage of the rear mech that guide the chain round the sprockets) because they pick up hard-packed dirt from the chain.

BBC: Sport