Wheel and axle: Difference between revisions
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The '''wheel and axle''' is a [[simple machine]]. A ''wheel and axle'' is a [[lever]] of the first |
The '''wheel and axle''' is a [[simple machine]]. A ''wheel and axle'' is a modified [[lever]] of the first class<ref>Elroy McKendree Avery, Elementary Physics, New York : Sheldon & Company, 1878.</ref> that rotates in a circle around a center point or [[fulcrum]]. The larger [[wheel]] (or outside) rotates around the smaller wheel ([[axle]]). Bicycle wheels, [[ferris wheel]]s, and [[gear]]s are all examples of a wheel and axle. Wheels can also have a solid [[shaft]] with the center core as the axle such as a [[screwdriver]] or [[drill bit]] or the [[log]] in a [[log rolling]] contest. |
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The traditional form as recognized in 19th century textbooks is as shown in the image. This also shows the most widely recognized application, i.e., lifting water from a well. The form consists of a wheel that turns an axle and in turn a rope converts the rotational motion to linear motion for the purpose of lifting. |
The traditional form as recognized in 19th century textbooks is as shown in the image. This also shows the most widely recognized application, i.e., lifting water from a well. The form consists of a wheel that turns an axle and in turn a rope converts the rotational motion to linear motion for the purpose of lifting. |
Revision as of 20:42, 12 March 2010
The wheel and axle is a simple machine. A wheel and axle is a modified lever of the first class[1] that rotates in a circle around a center point or fulcrum. The larger wheel (or outside) rotates around the smaller wheel (axle). Bicycle wheels, ferris wheels, and gears are all examples of a wheel and axle. Wheels can also have a solid shaft with the center core as the axle such as a screwdriver or drill bit or the log in a log rolling contest.
The traditional form as recognized in 19th century textbooks is as shown in the image. This also shows the most widely recognized application, i.e., lifting water from a well. The form consists of a wheel that turns an axle and in turn a rope converts the rotational motion to linear motion for the purpose of lifting.
By considering the machine as a torque multiplier, i.e., the output is a torque, items such as gears and screwdrivers can fall within this category.
Calculating mechanical advantage
Ideal mechanical advantage
The ideal mechanical advantage of a wheel and axle is calculated with the following formula:
Actual mechanical advantage
The actual mechanical advantage of a wheel and axle is calculated with the following formula:
where
- R = resistance force, i.e. the weight of the bucket in this example.
- Eactual = actual effort force, the force required to turn the wheel
Examples
- Doorknobs are similar to the water well, as the mechanism uses the axle as a pinion to withdraw the latch.
- With a simple chain fall, the user pulls on the wheel using the input chain, so the input motion is actually linear.
- Screwdrivers - an example of the rotational form. The diameter of the handle gives a mechanical advantage.
- Gears
- Bicycle wheels
- Ferris wheels
See also
Notes
- ^ Elroy McKendree Avery, Elementary Physics, New York : Sheldon & Company, 1878.