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Gear inches is one way of measuring the gear ratio(s) of a bicycle, so that different gears and different bicycles can be compared in a consistent manner. Gear inches is an imperial measure corresponding to the diameter in inches of the drive wheel of a penny-farthing bicycle with equivalent ( direct-drive ) gearing.
[a] As the tire RPM at maximum speed is not the same as the engine RPM at that power, a transmission is used with a gear ratio to convert one to the other. [b] At even slightly lower speeds than maximum, the total drag on the vehicle is considerably less, and the engine needs to deliver this greatly reduced amount of power.
One standard option for the Brompton folding bicycle is to use a 3-speed hub gear (roughly a 30% difference between gear ratios) in combination with a 2-speed derailleur gear (roughly a 15% difference) to give 6 distinct gear ratios; this is an example of half-step gearing. Some Brompton suppliers offer a 2-speed chainring 'Mountain Drive' as ...
The gear ratios in transmission and final drive are important because different gear ratios will change the characteristics of a vehicle's performance. Valve timing gears on a Ford Taunus V4 engine — the small gear is on the crankshaft, the larger gear is on the camshaft. The crankshaft gear has 34 teeth, the camshaft gear has 68 teeth and ...
The gear range is difference between the highest and lowest gear ratios and may be expressed as a percentage (e.g., 500%) or as a ratio (e.g., 5:1). Heel [ edit ]
Worm-and-gear sets are a simple and compact way to achieve a high torque, low speed gear ratio. For example, helical gears are normally limited to gear ratios of less than 10:1 while worm-and-gear sets vary from 10:1 to 500:1. [45] A disadvantage is the potential for considerable sliding action, leading to low efficiency. [46]
The involute gear profile, sometimes credited to Leonhard Euler, [1] was a fundamental advance in machine design, since unlike with other gear systems, the tooth profile of an involute gear depends only on the number of teeth on the gear, pressure angle, and pitch. That is, a gear's profile does not depend on the gear it mates with.
A cycloidal drive or cycloidal speed reducer is a mechanism for reducing the speed of an input shaft by a certain ratio. Cycloidal speed reducers are capable of relatively high ratios in compact sizes with very low backlash. [1] The input shaft drives an eccentric bearing that in turn drives the cycloidal disc in an eccentric, cycloidal motion ...