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Many practical applications suggest as good practice that the maximum operating speed should not exceed 75% of the critical speed [citation needed]; however, some systems operate above the first critical speed, or supercritically. In such cases, it is important to accelerate the shaft through the first natural frequency quickly so that large ...
When an element of mass is offset from the axis of rotation, centrifugal force will tend to pull the mass outward. The elastic properties of the shaft will act to restore the “straightness”. If the frequency of rotation is equal to one of the resonant frequencies of the shaft, whirling will occur. In order to save the machine from failure ...
Dynamic Runabout 7 shaft-driven bicycle Drive-shaft housing. A shaft-driven bicycle is a bicycle that uses a drive shaft instead of a chain to transmit power from the pedals to the wheel. Shaft drives were introduced in the 1880s, but were mostly supplanted by chain-driven bicycles due to the gear ranges possible with sprockets and derailleurs ...
In 1991, a two-wheel drive bicycle was marketed under the Legacy name. It used a flexible shaft and two bevel gears to transmit torque from the rear wheel, driven by a conventional bicycle chain with derailleurs, to the front wheel. [11] In 1994, Steve Christini and Mike Dunn introduced a two-wheel drive option. [12]
Bicycle gearing is the aspect of a bicycle drivetrain that determines the relation between the cadence, the rate at which the rider pedals, and the rate at which the drive wheel turns. On some bicycles there is only one gear and, therefore, the gear ratio is fixed , but most modern bicycles have multiple gears and thus multiple gear ratios.
From a mechanical viewpoint, up to 99% of the mechanical energy delivered by the rider into the pedals is transmitted to the wheels (clean, lubricated new chain at 400 W), although the use of gearing mechanisms reduces this by 1–7% (clean, well-lubricated derailleurs and a straight chainline), 4–12% (chain with 3-speed hubs), or 10–20% (shaft drive with 3-speed hubs).
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 ...
Analysis shows that there are well-damped critical speed at lower speed range. Another critical speed at mode 4 is observed at 7810 rpm (130 Hz) in dangerous vicinity of nominal shaft speed, but it has 30% damping - enough to safely ignore it. Analytically computed values of eigenfrequencies as a function of the shaft's rotation speed. This ...