Name: wedges and self-locking stability
Uploaded: 2025-05-22T09:06:04.000Z
Duration: 1 min 24 s
Channel: JoVE

Ein Keil ist eine Maschine, die nützlich ist, um die Höhe von strukturellen oder mechanischen Teilen anzupassen, Stabilität für schwere Objekte zu gewährleisten und einen Körper in zwei Teile zu teilen.
Erwägen Sie, einen Keil zu verwenden, um eine schwere Platte anzuheben.
Der Keil verstärkt die ausgeübte Kraft in eine viel größere Kraft, die fast senkrecht zur aufgewendeten Kraft gerichtet ist.
Es gibt sieben Unbekannte, darunter die aufgebrachte Kraft für die Bewegung des Keils und sechs Normal- und Reibungskräfte.
Sie können anhand von vier Kraftgleichgewichtsgleichungen, die auf den Keil und die Platte angewendet werden, und drei Reibungsgleichungen, die auf jede Kontaktfläche angewendet werden, bestimmt werden.
Um die Platte abzusenken, wirken die Reibungskräfte im umgekehrten Sinne.
Sofern der Reibungskoeffizient sehr klein oder der Keilwinkel groß ist, muss die aufgebrachte Kraft nach rechts wirken, um die Platte zu halten.
Wird die aufgebrachte Kraft weggenommen und halten Reibungskräfte den Block fest, gilt der Keil als selbsthemmend. Diese Bedingung ist nur gültig, wenn der Keilwinkel kleiner als doppelt so groß ist wie der Winkel, den die Reaktionskräfte erzeugen.

<ol>
	<li>Hibbeler, R.C. (2016). Technische Mechanik: Statik. Vierzehnte Auflage, New Jersey: Pearson. S. 430-431.</li>
	<li>Meriam, J.L., Kraige, L.G. und Bolten, J.N. (2016). Technische Mechanik: Statik und Dynamik. Achte Auflage, Singapur: John Wiley & Sons. S. 353-354.</li>
	<li>Bier, F.P., Johnston, E.R., Mazurek, D.F., Cornwell, P.J. und Self, B.P. (2016). Vektormechanik für Ingenieure. Elfte Auflage, New York: McGraw-Hill Education. S. 450.</li>
</ol>

keile

Ein Keil ist eine einfache Maschine, die verschiedene Zwecke erfüllt, wie zum Beispiel das Einstellen der Höhe von Struktur- oder mechanischen Teilen, die Bereitstellung von Stabilität für schwere Objekte und das Aufteilen eines Körpers in zwei Teile. Dieses vielseitige Werkzeug kann eine aufgebrachte Kraft verstärken und so das Manipulieren großer oder schwerer Objekte erleichtern. Denken Sie daran, einen Keil zu verwenden, um eine schwere Platte anzuheben. Hier funktioniert der Keil, indem er die aufgebrachte Kraft in eine deutlich größere Kraft umwandelt, die fast senkrecht zur anfänglichen Kraft gerichtet ist. Diese Verstärkung ermöglicht das Anheben schwerer Gegenstände mit minimalem Aufwand. Es gibt sieben unbekannte Faktoren, die an der Bewegung des Keils beteiligt sind: die aufgebrachte Kraft und sechs normale und reibungsbedingte Kräfte. In den Freikörperdiagrammen wird das Gewicht des Keils oft vernachlässigt, da es im Vergleich zur Last gering ist. <img alt="Figure 1" src="/files/ftp_upload/14317/14317_PT_Figure_1v2.svg" style="text-align: center; height: 300px;"> Diese Unbekannten können unter Verwendung von vier Gleichgewichtsgleichungen auf den Keil und die Platte bestimmt werden. <img alt="Equation 1" src="/files/ftp_upload/14317/14317_PT_Equation_1v2.svg" style="text-align: center; height: 13px;"> <img alt="Equation 2" src="/files/ftp_upload/14317/14317_PT_Equation_2v2.svg" style="text-align: center; height: 13px;"> <img alt="Equation 3" src="/files/ftp_upload/14317/14317_PT_Equation_3v2.svg" style="text-align: center; height: 13px;"> <img alt="Equation 4" src="/files/ftp_upload/14317/14317_PT_Equation_4v2.svg" style="text-align: center; height: 13px;"> Und die verbleibenden drei Reibungsgleichungen (F1, F2, F3), die an jeder Kontaktfläche angewendet werden, sind durch den Reibungskoeffizienten und ihre jeweiligen Normalkräfte gegeben. Durch Lösen dieser Gleichungen kann man Einblicke in das Verhältnis zwischen der aufgebrachten Kraft und der resultierenden Bewegung des Keils gewinnen. Beim Absenken der Platte wirken die Reibungskräfte in entgegengesetzter Richtung. Vorausgesetzt, der Reibungskoeffizient ist sehr gering oder der Keilwinkel ist groß, muss die aufgebrachte Kraft nach rechts wirken, um die Platte an Ort und Stelle zu halten. Das Gleichgewicht der Kräfte stellt sicher, dass der Keil stabil bleibt und seine Position beibehält, während er das Gewicht der Platte trägt. Unter bestimmten Bedingungen kann der Keil als selbstverriegelnd betrachtet werden. Dies tritt auf, wenn die aufgebrachte Kraft entfernt wird und allein die Reibungskräfte den Block halten können. Die Selbstverriegelungsbedingung gilt nur dann, wenn der Keilwinkel kleiner ist als das Doppelte des Winkels, der von den Reaktionskräften gebildet wird. In diesem Fall wirken die Geometrie des Keils und die Reibung zwischen den Kontaktflächen zusammen, um unerwünschte Bewegungen oder Abrutschen zu verhindern. Die selbstverriegelnde Eigenschaft eines Keils kann in verschiedenen Anwendungen vorteilhaft sein, da sie zusätzliche Stabilität und Sicherheit beim Manipulieren schwerer Objekte bietet. Zum Beispiel kann ein selbstverriegelnder Keil in Bauprojekten oder Ingenieurprojekten dazu beitragen, dass strukturelle Komponenten beim Zusammenbau oder bei Anpassungen fest an ihrem Platz bleiben.

Keile

Ein Keil ist eine einfache Maschine, die verschiedenen Zwecken dient, z. B. zum Einstellen der Höhe von strukturellen oder mechanischen Teilen, um Stabilität für schwere ...

Education

Lehre

JoVE Core

Mechanical Engineering

Maschinenbau

Unit 1

Einheit 1

Friction

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KEY TERMS AND CONCEPTS

KERNBEGRIFFE UND KONZEPTE

Wedges

wedges and self-locking stability

A wedge is a simple machine that can lift, support, and split heavy objects. It can also change the height of structural or mechanical parts. Because it amplifies force, a wedge makes it easier to move or hold large loads with less effort.

One example is lifting a heavy slab. In that case, the wedge turns the applied force into a much larger force that acts almost perpendicular to the original push. That force change helps raise the load without requiring a large input force.

To analyze wedge motion, there are seven unknowns. These include the applied force, six normal forces, and frictional forces at the contact surfaces. The wedge weight is often ignored in the free-body diagrams because it is small compared with the load.

The unknowns can be found with four force equilibrium equations for the wedge and the slab. Three friction equations, F1, F2, and F3, are then applied at each contact surface. Each friction force equals the coefficient of friction times the normal force at that surface.

The same force balance also explains what happens when the slab is lowered. In that case, the friction forces act in the opposite direction. If the coefficient of friction is very small or the wedge angle is large, the applied force must act to the right to keep the slab in place.

A wedge can also be self-locking. This means that when the applied force is removed, friction alone can hold the block in place. The self-locking condition works only when the wedge angle is less than twice the angle made by the reaction forces.

This stability is useful in many settings. In construction or engineering work, a self-locking wedge can help keep parts firmly in place during assembly or adjustment. The geometry of the wedge and the friction between surfaces work together to reduce slipping and unwanted motion.

Wedges and Self-Locking Stability

dry friction

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kinetic friction

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wedges

A wedge is a simple machine that can lift, support, and split heavy objects. It can also change the height of structural or mechanical parts. Because it amplifies force, a wedge makes it easier to move or hold large loads with less effort. One example is lifting a heavy slab. In that case, the wedge turns the applied force into a much larger force that acts almost perpendicular to the original push. That force change helps raise the load without requiring a large input force. To analyze wedge...

frictional forces on screws

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self-locking screw

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collar bearings

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rolling resistance

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rolling resistance: problem solving

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key terms and concepts

Learn how wedges amplify force, lift heavy slabs, and stay in place through friction. Explore equilibrium, contact forces, and self-locking stability.

Wedges and Self-Locking Stability | JoVE K12

JoVE Core Mechanical Engineering offers concise, easy-to-understand animated videos covering key topics such as equilibrium, forces, truss analysis, and structural mechanics. Explore their real-world applications, and witness these concepts in action through scientist-led experiments.

mechanical engineering

Wedges and Self-Locking Stability

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