Gear ratios

When talking about gear ratios, do you specify the smaller or larger gear first?
Two meshed gears have a gear ratio of 3:1 Every time the larger gear
turns once, the smaller gear will turn?
a) 1/3 of the time b) 1 time c) 3 times
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don wrote:

drive:driven so as to indicate a reduction or an overdrive.
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Gear ratio is driven: drive.....41 teeth on ring gear: 10 teeth on pinion is 4.10:1 ratio.
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Augustus wrote:

No, it's drive:driven as in the 4.10 revolutions of the pinion *drive* gear to the 1 revolution of the ring *driven* gear in your example.
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don wrote:

A - the drive gear turns 3 times to turn the driven gear 1 time
The ratio is expressed as Drive gear : Driven gear.
4.10:1 means the drive gear turns 4.1 times to turn the driven gear 1 time This is an under drive ratio
1:4 means that the drive gear turn 1 time and the driven gear turns 4 times This would be an over driven ratio.
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Steve W.
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If the large gear turns once, the smaller gear will turn three times.
3 to 1 means three times the teeth on the big gear as the small gear. Or the large gear has a root circle three times as large as the small gear. In a rear axle the ratio is turns of the drive shaft to turns of the tire. 3:1, three turns of the drive shaft to one turn of the tire.
Al
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